explanation blue bibcodes open ADS page with paths to full text
Author name code: manchester
ADS astronomy entries on 2022-09-14
author:"Manchester, Ward B. IV"
---------------------------------------------------------
Title: Modeling FETCH Observations of 2005 May 13 CME
Authors: Jensen, Elizabeth A.; Manchester, Ward B., IV; Wexler,
David B.; Kooi, Jason E.; Nieves-Chinchilla, Teresa; Jian, Lan K.;
Pevtsov, Alexei; Fung, Shing
2022arXiv220903350J Altcode:
This paper evaluates the quality of CME analysis that has been
undertaken with the rare Faraday rotation observation of an
eruption. Exploring the capability of the FETCH instrument hosted on
the MOST mission, a four-satellite Faraday rotation radio sounding
instrument deployed between the Earth and the Sun, we discuss the
opportunities and challenges to improving the current analysis
approaches.
---------------------------------------------------------
Title: Three-Dimensional Structure of the Corona During WHPI Campaign
Rotations CR-2219 and CR-2223
Authors: Lloveras, D. G.; Vásquez, A. M.; Nuevo, F. A.; Frazin, R. A.;
Manchester, W.; Sachdeva, N.; Van der Holst, B.; Lamy, P.; Gilardy, H.
2022JGRA..12730406L Altcode:
Differential emission measure tomography (DEMT) and white light
(WL) tomography were applied to study the three-dimensional (3D)
structure of the global solar corona for two Whole Heliosphere
and Planetary Interactions campaign periods, Carrington rotations
2219 and 2223. With DEMT, Solar Dynamics Observatory/Atmospheric
Imaging Assembly images were used to reconstruct the 3D coronal
electron density and temperature in the range of heliocentric
distance 1.02-1.25 R<SUB>⊙</SUB>. With WL tomography, Solar and
Heliospheric Observatory/Large Angle and Spectrometric COronagraph-C2
images were used to reconstruct the 3D electron density in the range
of heliocentric distance 2.5-6.0 R<SUB>⊙</SUB>. The two periods
were also simulated with the 3D-magneto-hydrodynamic Alfvén Wave
Solar Model (AWSoM), and its results compared in detail with the
reconstructions. The DEMT analysis reveals a 20% less dense and 20%
hotter corona than for rotations corresponding to the solar cycle
23/24 deep minimum. The electron density and temperature of the AWSoM
model agree with DEMT results within 10% and 20%, respectively, while
its electron density overestimates results of WL tomography up to
75%. The slow (fast) component of the terminal wind speed of the model
is found to be associated with field lines characterized by larger
(smaller) values of the tomographic density and temperature at the
coronal base. DEMT reconstructions reveal the coronal plasma to be
ubiquitously characterized by temperature variability of up to ≈45%
over spatial scales of order ∼10<SUP>4</SUP> km. Taking into account
this level of fine-structure by global models may be consequential
for their predictions on wave propagation in the corona.
---------------------------------------------------------
Title: Modern Faraday Rotation Studies to Probe the Solar Wind
Authors: Kooi, Jason E.; Wexler, David B.; Jensen, Elizabeth A.;
Kenny, Megan N.; Nieves-Chinchilla, Teresa; Wilson, Lynn B., III; Wood,
Brian E.; Jian, Lan K.; Fung, Shing F.; Pevtsov, Alexei; Gopalswamy,
Nat; Manchester, Ward B.
2022FrASS...941866K Altcode:
For decades, observations of Faraday rotation have provided unique
insights into the plasma density and magnetic field structure of
the solar wind. Faraday rotation (FR) is the rotation of the plane
of polarization when linearly polarized radiation propagates through
a magnetized plasma, such as the solar corona, coronal mass ejection
(CME), or stream interaction region. FR measurements are very versatile:
they provide a deeper understanding of the large-scale coronal magnetic
field over a range of heliocentric distances (especially ≈1.5 to
20 R⊙) not typically accessible to in situ spacecraft observations;
detection of small-timescale variations in FR can provide information
on magnetic field fluctuations and magnetohydrodynamic wave activity;
and measurement of differential FR can be used to detect electric
currents. FR depends on the integrated product of the plasma
density and the magnetic field component along the line of sight
to the observer; historically, models have been used to distinguish
between their contributions to FR. In the last two decades, though,
new methods have been developed to complement FR observations with
independent measurements of the plasma density based on the choice
of background radio source: calculation of the dispersion measure
(pulsars), measurement of Thomson scattering brightness (radio
galaxies), and application of radio ranging and apparent-Doppler
tracking (spacecraft). New methods and new technology now make it
possible for FR observations of solar wind structures to return not
only the magnitude of the magnetic field, but also the full vector
orientation. In the case of a CME, discerning the internal magnetic
flux rope structure is critical for space weather applications.
---------------------------------------------------------
Title: The impact of coronal mass ejections and flares on the
atmosphere of the hot Jupiter HD189733b
Authors: Hazra, Gopal; Vidotto, Aline A.; Carolan, Stephen; Villarreal
D'Angelo, Carolina; Manchester, Ward
2022MNRAS.509.5858H Altcode: 2021arXiv211104531H; 2021MNRAS.tmp.3019H
High-energy stellar irradiation can photoevaporate planetary
atmospheres, which can be observed in spectroscopic transits of hydrogen
lines. For the exoplanet HD189733b, multiple observations in the Ly α
line have shown that atmospheric evaporation is variable, going from
undetected to enhanced evaporation in a 1.5-yr interval. Coincidentally
or not, when HD189733b was observed to be evaporating, a stellar flare
had just occurred 8 h prior to the observation. This led to the question
of whether this temporal variation in evaporation occurred due to the
flare, an unseen associated coronal mass ejection (CME), or even the
simultaneous effect of both. In this work, we investigate the impact of
flares (radiation), winds, and CMEs (particles) on the atmosphere of
HD189733b using three-dimensional radiation hydrodynamic simulations
that self-consistently include stellar photon heating. We study four
cases: first, the quiescent phase including stellar wind; secondly,
a flare; thirdly, a CME; and fourthly, a flare that is followed by
a CME. Compared to the quiescent case, we find that the flare alone
increases the evaporation rate by only 25 per cent, while the CME leads
to a factor of 4 increments. We calculate Ly α synthetic transits and
find that the flare alone cannot explain the observed high blueshifted
velocities seen in the Ly α. The CME, however, leads to an increase
in the velocity of escaping atmospheres, enhancing the blueshifted
transit depth. While the effects of CMEs show a promising potential,
our models are not able to fully explain the blueshifted transit depths,
indicating that they might require additional physical mechanisms.
---------------------------------------------------------
Title: Improving the Alfvén Wave Solar Atmosphere Model Based on
Parker Solar Probe Data
Authors: van der Holst, B.; Huang, J.; Sachdeva, N.; Kasper, J. C.;
Manchester, W. B., IV; Borovikov, D.; Chandran, B. D. G.; Case, A. W.;
Korreck, K. E.; Larson, D.; Livi, R.; Stevens, M.; Whittlesey, P.;
Bale, S. D.; Pulupa, M.; Malaspina, D. M.; Bonnell, J. W.; Harvey,
P. R.; Goetz, K.; MacDowall, R. J.
2022ApJ...925..146V Altcode:
In van der Holst et al. (2019), we modeled the solar corona and inner
heliosphere of the first encounter of NASA's Parker Solar Probe (PSP)
using the Alfvén Wave Solar atmosphere Model (AWSoM) with Air Force
Data Assimilative Photospheric flux Transport-Global Oscillation Network
Group magnetograms, and made predictions of the state of the solar
wind plasma for the first encounter. AWSoM uses low-frequency Alfvén
wave turbulence to address the coronal heating and acceleration. Here,
we revise our simulations, by introducing improvements in the energy
partitioning of the wave dissipation to the electron and anisotropic
proton heating and using a better grid design. We compare the new AWSoM
results with the PSP data and find improved agreement with the magnetic
field, turbulence level, and parallel proton plasma beta. To deduce the
sources of the solar wind observed by PSP, we use the AWSoM model to
determine the field line connectivity between PSP locations near the
perihelion at 2018 November 6 UT 03:27 and the solar surface. Close
to the perihelion, the field lines trace back to a negative-polarity
region about the equator.
---------------------------------------------------------
Title: Predicting the Optimal Poynting Flux for Different Solar
Activity Conditions for Realtime Solar Wind Prediction
Authors: Huang, Zhenguang; Toth, Gabor; Gombosi, Tamas; Sachdeva,
Nishtha; Zhao, Lulu; Manchester, Ward; van der Holst, Bart; Sokolov,
Igor
2021AGUFMSH45D2395H Altcode:
Its critical to have an accurate solar wind background in the inner
heliosphere for space weather prediction, from the arrival of Corotating
Interaction Regions (CIRs), to the Coronal Mass Ejections (CMEs),
and Solar Energetic Particles (SEPs). In the space weather community,
there are two major approaches to predict the solar wind background:
one uses empirical or semi-empirical models, e.g., the Wang-Sheeley-Arge
(WSA) model; the other is based on first-principles model, e.g., the
Alfven Wave Solar atmosphere Model (AWSoM) developed at the University
of Michigan. In the past, it was difficult for physics models to
perform real-time solar wind predictions, because the computational
cost is much higher for physics-based models than for empirical or
semi-empirical models, and the optimal input parameters could be
different for different solar rotations in which case the user would
need to run the model with different input parameters to best predict
the solar wind. Nowadays, the computational cost is not a big issue
as super computers are much more powerful than before. The remaining
issue is that the input parameters could vary. In real-time solar
wind prediction, it is necessary to have optimal input parameters in
advance. In this presentation, we study the relation between one of the
most important parameters for AWSoM, the Poynting flux at the inner
boundary, and the magnetic field structure of the solar corona. We
obtain the optimal Poynting flux value for nine Carrington rotations
in the last solar cycle and correlate it with various characteristics
of the solar magnetic field, such as open flux, area of coronal holes,
etc.. The preliminary results are encouraging, and suggest that the
optimal parameter can be estimated from the magnetograms.
---------------------------------------------------------
Title: SOFIE (Solar-wind with Field-lines and Energetic-particles):
A data-driven and self-consistent SEP modeling and forecasting tool
Authors: Zhao, Lulu; Sokolov, Igor; Gombosi, Tamas; Tenishev, Valeriy;
Huang, Zhenguang; Toth, Gabor; Sachdeva, Nishtha; Manchester, Ward;
van der Holst, Bart
2021AGUFMSH55F1900Z Altcode:
We present a data-driven and self-consistent SEP model, SOFIE, to
simulate the acceleration and transport processes of energetic particles
using the Space Weather Modeling Framework (SWMF). In this model, the
background solar wind plasma in the solar corona and interplanetary
space are modeled by the Alfven Wave Solar-atmosphere Model(-Realtime)
(AWSoM(-R)) driven by the near-real-time hourly updated GONG (bihourly
ADAPT-GONG) magnetograms. In the background solar wind, the CMEs
are launched employing the Eruptive Event Generator using Gibson-Low
configuration (EEGGL), by inserting a flux rope estimated from the free
magnetic energy in the active region. The acceleration and transport
processes are then modeled self-consistently by the multiple magnetic
field line tracker (M-FLAMPA) and the Adaptive Mesh Particle Simulator
(AMPS). We will demonstrate the capability of SOFIE to demystify the
acceleration processes by the CME-driven shock in the low corona and the
modulation of energetic particles by the solar wind structures. Besides,
using selected historical SEP events, e.g. 2013 Apr 11 event, we will
illustrate the progresses toward a faster-than-real-time prediction
of SEPs.
---------------------------------------------------------
Title: AWSoM MHD simulation of a solar active region with realistic
spectral synthesis
Authors: Manchester, Ward; Shi, Tong; Landi, Enrico; Szente, Judit;
van der Holst, Bart; Chen, Yuxi; Toth, Gabor; Bertello, Luca; Pevtsov,
Alexander
2021AGUFMSH12B..02M Altcode:
For the first time, we simulate the detailed spectral line emission
from a solar active region (AR) with the Alfven Wave Solar Model
(AWSoM). We select an active region appearing near disk center on
2018 July 13 and use an NSO-HMI synoptic magnetogram to specify the
magnetic field at the model's inner boundary. To resolve smaller-scale
magnetic features, we apply adaptive mesh refinement to resolve the
AR with a spatial resolution of 0.37 degrees, four times higher than
the background corona. We then apply the SPECTRUM code informed with
Chianti spectral emissivities to calculate more than a dozen spectral
lines forming at temperatures ranging from 0.5 to 3+ MK. Comparisons
are made between these simulated line profiles and those observed by
the Hinode/EIS instrument where we find close agreement (within a
20% margin of error of peak intensity) across a wide range of loop
sizes and temperatures. We also compare the differential emission
measure calculated from both the simulation and EIS observation to
further show the model's ability to capture the plasma temperature and
density. Finally, we simulate and compare Doppler velocities and find
that simulated flow patterns to be of comparable magnitude to what
is observed. Our results demonstrate the broad applicability of the
low-frequency Alfven wave balanced turbulence theory for explaining
the heating of coronal loops.
---------------------------------------------------------
Title: AWSoM context simulations for Parker Solar Probe encounter 7
Authors: van der Holst, Bart; Manchester, Ward; Klein, Kristopher
2021AGUFMSH15C2045V Altcode:
We compare Alfven Wave Solar atmosphere Model (AWSoM) simulations
with the seventh orbit of NASAs Parker Solar Probe (PSP). The
perihelion of this encounter is 20.3 Rsun reached at 2021-01-01. In
the AWSoM model, the coronal heating and acceleration is addressed
via low-frequency, reflection-driven Alfven waves. The nonlinear
interaction of counter-propagating waves results in a turbulent energy
cascade. The dissipated wave energy is then apportioned to electron and
anisotropic proton temperatures. We check the ability of the simulations
to reproduce the observed plasma mass density, velocity, and magnetic
fields, temperature anisotropy, and wave turbulence levels. To deduce
the sources of the solar wind observed by PSP we use the AWSoM model
to determine the field line connectivity between PSP locations and the
Sun. We will also describe the large-scale structures that PSP might
have passed through, for instance whether PSP was in the fast or slow
wind and when PSP crossed the heliospheric current sheet. We emphasize
the proton temperature anisotropies and check for the occurrence of
plasma instabilities.
---------------------------------------------------------
Title: Novel Magnetic Field and Electron Density Measurements of
CMEs (within AU) with the Proposed Multiview Observatory for Solar
Terrestrial Science (MOST) Mission
Authors: Jensen, P. E., C. S. P., Elizabeth; Manchester, Ward; Fung,
Shing; Gopalswamy, Nat; Jian, Lan; Kenny, Megan; Kooi, Jason; Lazio,
Joseph; Li, Lihua; Nieves-Chinchilla, Teresa; Pevtsov, Alexei; Wexler,
David; Wilson, Lynn; Wood, Brian; Bale, Stuart; Bastian, Tim
2021AGUFMSH33A..08J Altcode:
The Multiview Observatory for Solar Terrestrial Science (MOST) mission
concept will be the most advanced solar observatory to date (Gopalswamy
et al, SH0001, 2021). Comprising four spacecraft, two located in the L4
and ahead of L4 position and two located in the L5 and behind of the L5
position, the four lines-of-sight (LOSs) form the basis for the unique
Faraday Effect Tracker of Coronal and Heliospheric Structures (FETCH)
instrument (Wexler et al, SH0019, 2021). We report on our modeling
into the expected Faraday rotation (FR) caused by an Earth-directed
CME crossing the MOST/FETCH radio-sensing paths using a heliospheric
3-D MHD model to obtain the necessary LOS data on electron density
and magnetic field components (see example image). Specifically, we
utilized simulation data of the 2005 May 13 CME (Manchester IV et al.,
2014, Plasma Phys. Control. Fusion), which erupted from the north-south
polarity inversion line of AR 10759 at 16:03 UT, reaching speeds around
2000 km/s in the corona. The trajectory of the CME at an acute angle
to the Earth-Sun line crosses each FETCH LOS at a different time. Two
LOSs are at different viewing angles with little overlap between
the CME sheath and magnetic flux rope core. A blind test fitting of
the Faraday rotation functions (Figures 6 and 7 in Jensen et al.,
2010, Sol. Phys.) to the simulated FETCH observations reproduced the
orientation of the CME for its handedness as well as its associated
complementary degenerate solution. In conclusion, one of the four
LOSs will be more sensitive to observing CME flux rope structure of
Earthward CMEs, depending on their trajectory. We find that two of the
four LOSs enable analyzing CME evolution, whereas the other two LOSs
enable analyzing the average magnetic field vector in the corresponding
high density regions dominating the measurements at that time. For
example, the average sheath magnetic field vector can be partially
measured in the plane of the ecliptic due to the angular differences
between 2 LOSs. We discuss future work as this effort develops.
---------------------------------------------------------
Title: FETCH Concept: Investigating Quiescent and Transient Magnetic
Structures in the Inner Heliosphere using Faraday Rotation of
Spacecraft Radio Signals
Authors: Wexler, David; Jensen, Elizabeth; Gopalswamy, Nat; Wilson,
Lynn; Fung, Shing; Nieves-Chinchilla, Teresa; Jian, Lan; Bastian,
Tim; Pevtsov, Alexei; Manchester, Ward; Kenny, Megan; Lazio, Joseph;
Wood, Brian; Kooi, Jason
2021AGUFMSH31A..05W Altcode:
The Faraday Effect Tracker of Coronal and Heliospheric structures
(FETCH) is a new instrument concept being developed to probe coronal
and interplanetary magnetic field structures in the ambient solar wind,
corotating interaction regions and coronal mass ejections (CMEs) as
they evolve in the inner heliosphere. FETCH is one of the instruments
that constitute the Multiview Observatory for Solar Terrestrial (MOST)
science mission. FETCH will measure Faraday rotation (FR) of linearly
polarized spacecraft radio signals transmitted along four lines of sight
provided by the four MOST spacecraft: two large spacecraft deployed
at Sun-Earth Lagrange points 4 and 5 and two smaller spacecraft, one
ahead of L4 and the other behind L5. FETCH will transmit and receive at
selected radio frequencies in the 1-100 MHz range for lines of sight
with solar impact parameters < 0.5 AU. FR yields the line-of-sight
(LOS) integrated product of electron number density and LOS-projected
magnetic field strengths. The FR measurements will be obtained from
the Stokes polarization parameters while additional plasma parameters,
such as electron column density, will be extracted from other signal
diagnostics. The multifrequency FR data and four lines-of-sight
will be used to constrain the magnetic field topology and dynamics of
interplanetary plasma structures upstream from Earth. Unique to this FR
experiment, the FETCH transmitter-receiver instrumentation is positioned
such that the entire sensing path remains in interplanetary space, thus
avoiding the complications of trans-ionospheric FR observations. The
FETCH key science objectives include: (1) characterizing CME magnetic
field structure and flux rope orientation, (2) tracking CME propagation
and shock signatures, (3) understanding the magnetic field features
of corotating interaction regions in the extended corona and inner
heliosphere, and (4) determination of large-scale MHD wave organization
in regions of developed ambient solar wind and its evolution during
perturbed flows. The MOST mission will build upon the achievements of
the Solar Heliospheric Observatory (SOHO) and the Solar Terrestrial
Relations Observatory (STEREO) missions during the last couple of
decades. FETCH will help fill the long-standing measurement gap of
magnetic field data in the inner heliosphere.
---------------------------------------------------------
Title: The Multiview Observatory for Solar Terrestrial Science (MOST)
Authors: Gopalswamy, Nat; Kucera, Therese; Leake, James; MacDowall,
Robert; Wilson, Lynn; Kanekal, Shrikanth; Shih, Albert; Christe,
Steven; Gong, Qian; Viall, Nicholeen; Tadikonda, Sivakumar; Fung,
Shing; Yashiro, Seiji; Makela, Pertti; Golub, Leon; DeLuca, Edward;
Reeves, Katharine; Seaton, Daniel; Savage, Sabrina; Winebarger, Amy;
DeForest, Craig; Desai, Mihir; Bastian, Tim; Lazio, Joseph; Jensen,
P. E., C. S. P., Elizabeth; Manchester, Ward; Wood, Brian; Kooi,
Jason; Wexler, David; Bale, Stuart; Krucker, Sam; Hurlburt, Neal;
DeRosa, Marc; Pevtsov, Alexei; Tripathy, Sushanta; Jain, Kiran;
Gosain, Sanjay; Petrie, Gordon; Kholikov, Shukirjon; Zhao, Junwei;
Scherrer, Philip; Woods, Thomas; Chamberlin, Philip; Kenny, Megan
2021AGUFMSH12A..07G Altcode:
The Multiview Observatory for Solar Terrestrial Science (MOST) is a
comprehensive mission concept targeting the magnetic coupling between
the solar interior and the heliosphere. The wide-ranging imagery and
time series data from MOST will help understand the solar drivers and
the heliospheric responses as a system, discerning and tracking 3D
magnetic field structures, both transient and quiescent in the inner
heliosphere. MOST will have seven remote-sensing and three in-situ
instruments: (1) Magnetic and Doppler Imager (MaDI) to investigate
surface and subsurface magnetism by exploiting the combination of
helioseismic and magnetic-field measurements in the photosphere; (2)
Inner Coronal Imager in EUV (ICIE) to study large-scale structures
such as active regions, coronal holes and eruptive structures by
capturing the magnetic connection between the photosphere and the
corona to about 3 solar radii; (3) Hard X-ray Imager (HXI) to image
the non-thermal flare structure; (4) White-light Coronagraph (WCOR) to
seamlessly study transient and quiescent large-scale coronal structures
extending from the ICIE field of view (FOV); (5) Faraday Effect
Tracker of Coronal and Heliospheric structures (FETCH), a novel radio
package to determine the magnetic field structure and plasma column
density, and their evolution within 0.5 au; (6) Heliospheric Imager
with Polarization (HIP) to track solar features beyond the WCOR FOV,
study their impact on Earth, and provide important context for FETCH;
(7) Radio and Plasma Wave instrument (M/WAVES) to study electron beams
and shocks propagating into the heliosphere via passive radio emission;
(8) Solar High-energy Ion Velocity Analyzer (SHIVA) to determine spectra
of electrons, and ions from H to Fe at multiple spatial locations
and use energetic particles as tracers of magnetic connectivity; (9)
Solar Wind Magnetometer (MAG) to characterize magnetic structures at
1 au; (10) Solar Wind Plasma Instrument (SWPI) to characterize plasma
structures at 1 au. MOST will have two large spacecraft with identical
payloads deployed at L4 and L5 and two smaller spacecraft ahead of L4
and behind L5 to carry additional FETCH elements. MOST will build upon
SOHO and STEREO achievements to expand the multiview observational
approach into the first half of the 21st Century.
---------------------------------------------------------
Title: Global Sensitivity Analysis for Solar-Wind Simulations in
the Space Weather Modelling Framework
Authors: Jivani, Aniket; Huan, Xun; Chen, Yang; van der Holst, Bart;
Zou, Shasha; Huang, Zhenguang; Sachdeva, Nishtha; Iong, Daniel;
Manchester, Ward; Toth, Gabor
2021AGUFMSH55C1851J Altcode:
The Space Weather Modelling Framework (SWMF) offers efficient and
flexible sun-to-earth simulations based on coupled first principles
and/or empirical models. This encompasses computing the quiet solar
wind, generating a coronal mass ejection (CME), propagating the CME
through the heliosphere, and calculating the magnetospheric impact via
geospace models. The predictions from these different steps and models
are affected by uncertainty and variation of many model inputs and
parameters, such as the Poynting flux emanating from the photosphere
and driving and heating the solar wind. In this presentation, as part
of the NextGen SWMF project funded by NSF, we perform uncertainty
quantification (UQ) for the quiet solar wind simulations produced by
our Alfven Wave Solar atmosphere Model (AWSoM). We first catalogue
the various sources of uncertainty and their distributions, and then
propagate the uncertainty to key predictive quantities of interest, the
in-situ solar wind and magnetic field at 1 au, through space-filling
designs of high-fidelity simulations. Using this dataset, we then
build polynomial chaos surrogate models that offer a convenient route
to global sensitivity analysis, which quantifies the contribution
of each input parameters uncertainty towards the variability of the
QoIs. The resulting Sobol sensitivity index allows us to rank and retain
only the most impactful parameters going forward, thereby achieving
dimension-reduction of the stochastic space. We have performed this
UQ analysis for both solar maximum and solar minimum conditions,
and we will summarize our findings in this presentation.
---------------------------------------------------------
Title: Developing the Michigan Sun-to-Earth Model with Data
Assimilation and Quantified Uncertainty
Authors: Toth, Gabor; Chen, Yang; Huan, Xun; van der Holst, Bart;
Zou, Shasha; Jivani, Aniket; Iong, Daniel; Sachdeva, Nishtha; Huang,
Zhenguang; Chen, Yuxi; Gaenko, Alexander; Manchester, Ward
2021AGUFMSH53B..06T Altcode:
As part of the Space Weather with Quantified Uncertainty program, our
project, funded by NSF, has been working on developing the Michigan
Sun-to-Earth Model with Data Assimilation and Quantified Uncertainty
(MSTEM-QUDA). In this talk we will summarize the main goals of the
project and report our progress. Using sophisticated experimental
design and fully automated scripts, we have performed many hundreds
of simulations with our solar corona and heliosphere model generating
steady state solar wind solutions. Based on these simulations, we have
completed the uncertainty quantification analysis. One important finding
is that the physically meaningful range of certain model parameters
depends on the solar cycle. We will use an ensemble of background
solar wind model solutions as a starting point for simulating coronal
mass ejections. Our preliminary model runs show promising accuracy for
the CME arrival time. We have also ported the Geospace model, a large
part of MSTEM-QUDA, to run efficiently on a GPU. In fact, we can run
the operational Geospace model on a single GPU significantly faster
than real time at the same speed as using about 100 CPU cores. The
Michigan Sun-to-Earth Model is available as an open-source distribution
at https://github.com/MSTEM-QUDA to the entire community.
---------------------------------------------------------
Title: Tracking the Source of Solar Type II Bursts through Comparisons
of Simulations and Radio Data
Authors: Hegedus, Alexander M.; Manchester, Ward B.; Kasper, Justin C.
2021ApJ...922..203H Altcode: 2021arXiv210207875H
The most intense solar energetic particle events are produced by
coronal mass ejections (CMEs) accompanied by intense type II radio
bursts below 15 MHz. Understanding where these type II bursts are
generated relative to an erupting CME would reveal important details
of particle acceleration near the Sun, but the emission cannot
be imaged on Earth due to distortion from its ionosphere. Here,
a technique is introduced to identify the likely source location of
the emission by comparing the dynamic spectrum observed from a single
spacecraft against synthetic spectra made from hypothesized emitting
regions within a magnetohydrodynamic (MHD) numerical simulation of the
recreated CME. The radio-loud 2005 May 13 CME was chosen as a test case,
with Wind/WAVES radio data being used to frame the inverse problem
of finding the most likely progression of burst locations. An MHD
recreation is used to create synthetic spectra for various hypothesized
burst locations. A framework is developed to score these synthetic
spectra by their similarity to the type II frequency profile derived
from the Wind/WAVES data. Simulated areas with 4× enhanced entropy and
elevated de Hoffmann-Teller velocities are found to produce synthetic
spectra similar to spacecraft observations. A geometrical analysis
suggests the eastern edge of the entropy-derived shock around (-30°,
0°) was emitting in the first hour of the event before falling off,
and the western/southwestern edge of the shock centered around (6°,
-12°) was a dominant area of radio emission for the 2 hr of simulation
data out to 20 solar radii.
---------------------------------------------------------
Title: Simulating Solar Maximum Conditions Using the Alfvén Wave
Solar Atmosphere Model (AWSoM)
Authors: Sachdeva, Nishtha; Tóth, Gábor; Manchester, Ward B.; van
der Holst, Bart; Huang, Zhenguang; Sokolov, Igor V.; Zhao, Lulu;
Shidi, Qusai Al; Chen, Yuxi; Gombosi, Tamas I.; Henney, Carl J.;
Lloveras, Diego G.; Vásquez, Alberto M.
2021ApJ...923..176S Altcode:
To simulate solar coronal mass ejections (CMEs) and predict their
time of arrival and geomagnetic impact, it is important to accurately
model the background solar wind conditions in which CMEs propagate. We
use the Alfvén Wave Solar atmosphere Model (AWSoM) within the the
Space Weather Modeling Framework to simulate solar maximum conditions
during two Carrington rotations and produce solar wind background
conditions comparable to the observations. We describe the inner
boundary conditions for AWSoM using the ADAPT global magnetic maps
and validate the simulated results with EUV observations in the low
corona and measured plasma parameters at L1 as well as at the position
of the Solar Terrestrial Relations Observatory spacecraft. This
work complements our prior AWSoM validation study for solar minimum
conditions and shows that during periods of higher magnetic activity,
AWSoM can reproduce the solar plasma conditions (using properly
adjusted photospheric Poynting flux) suitable for providing proper
initial conditions for launching CMEs.
---------------------------------------------------------
Title: Predicting the Background Solar Wind for Solar Maximum
Conditions with the Alfven Wave Solar atmosphere model (AWSoM)
Authors: Sachdeva, Nishtha; Toth, Gabor; Manchester, Ward; van der
Holst, Bart; Huang, Zhenguang; Sokolov, Igor; Zhao, Lulu; Al Shidi,
Qusai; Chen, Yuxi; Gombosi, Tamas; Henney, Carl
2021AGUFMSH45D2396S Altcode:
For physics-based simulations of the coronal mass ejections (CMEs)
it is essential to start with realistic background solar wind
conditions. To achieve this goal, we use the 3D extended MHD Alfven
Wave Solar atmosphere Model (AWSoM) to simulate the background plasma
environment during the magnetically active phase of solar cycle 24 and
validate the results with in situ and remote observations. Representing
the solar maximum conditions by two Carrington Rotations, we use the
ADAPT-HMI photospheric magnetic-field maps to drive AWSoM and simulate
the solar wind from the low corona to Earths orbit. We compare the AWSoM
predicted solar wind with EUV observations near the Sun as well as with
observed plasma and magnetic field parameters at L1 and at the STEREO
spacecraft location. We find that the optimal value for the Poynting
flux parameter of the model depends on the solar activity: for solar
maximum it has to be reduced by about a factor of two compared to the
solar minimum. Using properly adjusted Poynting flux parameters for the
solar maximum period results in a reasonable match with observations
for which quantitative comparisons show small margins of error. These
provide a reasonably accurate background solar wind into which a CME
will be launched.
---------------------------------------------------------
Title: A Numerical View of Stellar Coronal Mass Ejections and
Exoplanet Habitability
Authors: Alvarado Gomez, Julian; Drake, Jeremy; Cohen, Ofer;
Fraschetti, Federico; Garraffo, Cecilia; Poppenhaeger, Katja; Yadav,
Rakesh; Manchester, Ward
2021AGUFM.U43B..09A Altcode:
Coronal mass ejections (CMEs) are more energetic than any other class
of solar phenomena. They arise from the rapid release of up to 1033
erg of magnetic energy mainly in the form of particle acceleration and
bulk plasma motion. Their stellar counterparts, presumably involving
much larger energies, are expected to play a fundamental role in
shaping the environmental conditions around low-mass stars, in some
cases perhaps with catastrophic consequences for planetary systems
due to processes such as atmospheric erosion and depletion. Despite
their importance, the direct observational evidence for stellar CMEs
is almost non-existent. In this way, numerical simulations constitute
extremely valuable tools to shed some light on eruptive behaviour in
the stellar regime. In this talk, I will review recent results obtained
from realistic modelling of CMEs in active stars, highlighting their
key role in the interpretation of currently available observational
constraints. This includes studies performed on M-dwarf stars,
focusing on how emerging signatures in different wavelengths related
to these events vary as a function of the magnetic properties of
the star. Finally, the implications and relevance of these numerical
results will be discussed in the context of future characterisation
of host star-exoplanet systems.
---------------------------------------------------------
Title: What sustained multi-disciplinary research can achieve:
The space weather modeling framework
Authors: Gombosi, Tamas I.; Chen, Yuxi; Glocer, Alex; Huang, Zhenguang;
Jia, Xianzhe; Liemohn, Michael W.; Manchester, Ward B.; Pulkkinen,
Tuija; Sachdeva, Nishtha; Al Shidi, Qusai; Sokolov, Igor V.; Szente,
Judit; Tenishev, Valeriy; Toth, Gabor; van der Holst, Bart; Welling,
Daniel T.; Zhao, Lulu; Zou, Shasha
2021JSWSC..11...42G Altcode: 2021arXiv210513227G
Magnetohydrodynamics (MHD)-based global space weather models have
mostly been developed and maintained at academic institutions. While
the "free spirit" approach of academia enables the rapid emergence
and testing of new ideas and methods, the lack of long-term stability
and support makes this arrangement very challenging. This paper
describes a successful example of a university-based group, the Center
of Space Environment Modeling (CSEM) at the University of Michigan,
that developed and maintained the Space Weather Modeling Framework
(SWMF) and its core element, the BATS-R-US extended MHD code. It took
a quarter of a century to develop this capability and reach its present
level of maturity that makes it suitable for research use by the space
physics community through the Community Coordinated Modeling Center
(CCMC) as well as operational use by the NOAA Space Weather Prediction
Center (SWPC).
---------------------------------------------------------
Title: Localizing the Source of Type II Emission Around a CME with
the Sun Radio Interferometer Space Experiment (SunRISE) and MHD
Simulations
Authors: Hegedus, Alexander; Manchester, Ward; Kasper, Justin; Lazio,
Joseph; Romero-Wolf, Andrew
2021EGUGA..23.6435H Altcode:
The Earth"s Ionosphere limits radio measurements on its surface,
blocking out any radiation below 10 MHz. Valuable insight into many
astrophysical processes could be gained by having a radio interferometer
in space to image the low frequency window, which has never been
achieved. One application for such a system is observing type II
bursts that track solar energetic particle acceleration occurring at
Coronal Mass Ejection (CME)-driven shocks. This is one of the primary
science targets for SunRISE, a 6 CubeSat interferometer to circle
the Earth in a GEO graveyard orbit. SunRISE is a NASA Heliophysics
Mission of Opportunity that began Phase B (Formulation) in June 2020,
and plans to launch for a 12-month mission in mid-2023. In this work
we present an update to the data processing and science analysis
pipeline for SunRISE and evaluate its performance in localizing type
II bursts around a simulated CME.To create realistic virtual type II
input data, we employ a 2-temperature MHD simulation of the May 13th
2005 CME event, and superimpose realistic radio emission models on the
CME-driven shock front, and propagate the signal through the simulated
array. Data cuts based on different plasma parameter thresholds
(e.g. de Hoffman-Teller velocity and angle between shock normal and
the upstream magnetic field) are tested to get the best match to the
true recorded emission. This model type II emission is then fed to the
SunRISE data processing pipeline to ensure that the array can localize
the emission. We include realistic thermal noise dominated by the
galactic background at these low frequencies, as well as new sources
of phase noise from positional uncertainty of each spacecraft. We test
simulated trajectories of SunRISE and image what the array recovers,
comparing it to the virtual input, finding that SunRISE can resolve
the source of type II emission to within its prescribed goal of 1/3
the CME width. This shows that SunRISE will significantly advance the
scientific community"s understanding of type II burst generation, and
consequently, acceleration of solar energetic particles at CMEs. This
unique combination of SunRISE observations and MHD recreations of
space weather events will allow an unprecedented look into the plasma
parameters important for these processes.
---------------------------------------------------------
Title: Eruptive events in active stars: Lessons from numerical
simulations
Authors: Alvarado Gomez, J.; Drake, J. J.; Fraschetti, F.; Cohen,
O.; Poppenhaeger, K.; Garraffo, C.; Moschou, S.; Vocks, C.; Yadav,
R.; Manchester, W.
2021BAAS...53c0401A Altcode:
Flares and coronal mass ejections (CMEs) are more energetic than any
other class of solar phenomena. These events involve the rapid release
of up to 10<SUP>33</SUP> erg of magnetic energy in the form of particle
acceleration, heating, radiation, and bulk plasma motion. Displaying
much larger energies, their stellar counterparts are expected to play
a fundamental role in shaping the evolution of activity and rotation,
as well as the environmental conditions around low-mass stars. While
flares are now routinely detected in multi-wavelength observations
across all spectral types and ages, direct evidence for stellar CMEs
is almost non-existent. In this context, numerical simulations provide
a valuable pathway to shed some light on the eruptive behavior in the
stellar regime. In this talk, I will review recent results obtained
from realistic modeling of CMEs in active stars. Emphasis will be
given to M dwarfs, focusing on possible observable coronal signatures
of these events using next-generation X-ray missions. Furthermore, an
explanation for the lack of Type II radio bursts from CMEs in active
M dwarfs despite their frequent flaring will be discussed. Finally,
the implications and relevance of these numerical results will
be considered in the context of future characterization of host
star-exoplanet systems.
---------------------------------------------------------
Title: Threaded-field-line Model for the Low Solar Corona Powered
by the Alfvén Wave Turbulence
Authors: Sokolov, Igor V.; Holst, Bart van der; Manchester, Ward B.;
Su Ozturk, Doga Can; Szente, Judit; Taktakishvili, Aleksandre; Tóth,
Gábor; Jin, Meng; Gombosi, Tamas I.
2021ApJ...908..172S Altcode:
We present an updated global model of the solar corona, including the
transition region. We simulate the realistic three-dimensional (3D)
magnetic field using the data from the photospheric magnetic field
measurements and assume the magnetohydrodynamic (MHD) Alfvén wave
turbulence and its nonlinear dissipation to be the only source for
heating the coronal plasma and driving the solar wind. In closed-field
regions, the dissipation efficiency in a balanced turbulence is
enhanced. In the coronal holes, we account for a reflection of the
outward-propagating waves, which is accompanied by the generation
of weaker counterpropagating waves. The nonlinear cascade rate
degrades in strongly imbalanced turbulence, thus resulting in colder
coronal holes. The distinctive feature of the presented model is the
description of the low corona as almost-steady-state low-beta plasma
motion and heat flux transfer along the magnetic field lines. We trace
the magnetic field lines through each grid point of the lower boundary
of the global corona model, chosen at some heliocentric distance,
R = R<SUB>b</SUB> ∼ 1.1R<SUB>⊙</SUB>, well above the transition
region. One can readily solve the plasma parameters along the magnetic
field line from 1D equations for the plasma motion and heat transport
together with the Alfvén wave propagation, which adequately describe
the physics within the heliocentric distance range R<SUB>⊙</SUB>
< R < R<SUB>b</SUB>, in the low solar corona. By interfacing
this threaded-field-line model with the full MHD global corona model
at r = R<SUB>b</SUB>, we find the global solution and achieve a
faster-than-real-time performance of the model on ∼200 cores.
---------------------------------------------------------
Title: Probing the Puzzle of Fermi Long-Duration Gamma-Ray Flares
by Data-driven Global MHD Simulations
Authors: Jin, M.; Petrosian, V.; Liu, W.; Nitta, N.; Omodei, N.;
Effenberger, F.; Li, G.; Pesce-Rollins, M.; Allafort, A.; Manchester,
W.
2020AGUFMSH008..03J Altcode:
With the ever growing number of long-duration, >100 MeV gamma-ray
solar flares observed by Fermi/LAT, it poses a puzzle on the underlying
particle acceleration and transport mechanisms. Further challenges
come from (i) recent detection of gamma-rays in behind-the-limb (BTL)
flares (e.g., the 2014 September 1 event), in which the gamma-ray
emission region is located away from the BTL flare site by tens of
degrees in heliographic longitude, and (ii) migration of gamma-ray
emission centroids on the solar disk hours past the impulsive phase
(e.g., the 2012 March 7 event). Most of the long-duration events are
associated with fast CMEs, it is thus necessary to understand the role
of CMEs and CME-driven shocks in these events. To probe this puzzle,
we perform data-driven, global magnetohydrodynamics simulations of CMEs
associated with the long-duration gamma-ray flares. We investigate
the magnetic connectivity and evolution of the CME-driven shocks,
and their relationship, in both space and time, with the observed
gamma-ray emission. Specifically, we derive and track the time-varying
shock parameters over the area that is magnetically connected to the
gamma-ray emission region. Based on the modeling results, we discuss
the causes of Fermi long-duration gamma-ray events. In particular, we
address the possibility of CME shock-accelerated particles traveling
back to the Sun to produce gamma-rays, a scenario that bears potentially
paradigm-shifting implications on particle acceleration and transport
in solar eruptive events including flares and CMEs.
---------------------------------------------------------
Title: Three-Dimensional Tomographic Reconstruction and MHD Modeling
of the Solar Corona and Wind: WHPI Campaign Rotations CR-2219
and CR-2223
Authors: Lloveras, D.; Vásquez, A. M.; Nuevo, F.; Sachdeva, N.;
Manchester, W.; van der Holst, B.; Frazin, R. A.; Lamy, P.; Wojak, J.
2020AGUFMSH021..07L Altcode:
Accurate prediction of space weather conditions requires
state-of-the-art three-dimensional (3D) magnetohydrodynamic (MHD)
models, which need to be validated with observational data. The recent
deep minimum of solar activity, between solar cycles 24 and 25, renews
the opportunity to study the Sun-Earth connection under the simplest
solar and space environmental conditions. The international Whole
Heliosphere and Planetary Interactions (WHPI) initiative aims at this
specific purpose. In this work, we study two WHPI campaign periods,
the July 2019 total solar eclipse Carrington rotation (CR)-2019, and
the Parker Solar Probe and STEREO-A closest approach CR-2223. Based
on narrowband EUV data provided by the SDO/AIA instrument we carry
out tomographic reconstruction of the coronal electron density
and temperature in the range of heliocentric heights r ≤ 1.25
R<SUB>sun</SUB>. Based on visible light coronagraph data provided by
the SoHO/LASCO-C2 instrument we carry out tomographic reconstruction of
the coronal electron density and in the range of heliocentric heights
≈ 2.5-6.0 R<SUB>sun</SUB>. Applying ADAPT-GONG synoptic magnetograms
as boundary conditions, we use the Alfven Wave Solar Model (AWSoM)
to simulate the corona and solar wind for these time periods. We
study the capability of the 3D-MHD model to reproduce the tomographic
reconstructions in both closed and open coronal magnetic structures. In
coronal holes in particular, we investigate the correlation between
the reconstructed 3D distribution of the thermodynamical properties
in the low corona and the 3D distribution of the physical parameters
of the terminal solar wind of the model, discriminating its fast and
slow components
---------------------------------------------------------
Title: Simulating Solar Maximum Conditions with the Alfven Wave
Solar Atmosphere Model (AWSoM)
Authors: Sachdeva, N.; van der Holst, B.; Toth, G.; Manchester, W.;
Sokolov, I.
2020AGUFMSH0290015S Altcode:
The Alfven Wave Solar atmosphere Model (AWSoM) within the Space Weather
Modeling Framework (SWMF) is a physics-based solar corona model
that solves magnetohydrodynamic (MHD) equations along with Alfven
wave turbulence, radiative cooling and heat conduction. The Alfven
wave pressure and dissipation account for solar wind acceleration and
heating. AWSoM extends from the upper chromosphere up to 1 AU and beyond
and includes the description of electron temperature and perpendicular
and parallel proton temperature. AWSoM is driven by observations of the
photospheric magnetic field, which are applied at the inner boundary. In
this study, we use the ADAPT (Air Force Data Assimilative Photospheric
Flux Transport) synchronic maps to drive our solar corona model. The
ADAPT model uses observations of the solar photospheric magnetic field
to produce an ensemble of magnetic field maps using a flux-transport
model and data assimilation. We simulate solar maximum conditions using
AWSoM and compare the results with SDO/AIA observations in the low
corona and observations of solar wind density, speed and magnetic field
at 1 AU (OMNI data). The background solar wind derived from our model
provides the plasma environment into which Coronal Mass Ejections (CMEs)
can be launched. We use the Gibson-Low Flux Rope model to initiate a
CME and propagate it into the inner heliosphere. We validate the CME
simulation by comparing the results with remote as well as in-situ
observations from SOHO, SDO, STEREO, and WIND.
---------------------------------------------------------
Title: NextGen Space Weather Modeling Framework Using Physics,
Data Assimilation, Uncertainty Quantification and GPUs
Authors: Toth, G.; Zou, S.; Chen, Y.; Huan, X.; van der Holst, B.;
Manchester, W.; Liemohn, M. W.; Chen, Y.; Huang, Z.; Gaenko, A.
2020AGUFMSM015..05T Altcode:
We have been recently awarded a major NSF/NASA grant from the SWQU
program to develop the NextGen Space Weather Modeling Framework that
will employ computational models from the surface of the Sun to the
surface of Earth in combination with assimilation of observational
data to provide optimal probabilistic space weather forecasting. The
model will run efficiently on the next generation of supercomputers
to predict space weather about one day or more before the impact
occurs. The new project will concentrate on forecasting major space
weather events generated by coronal mass ejections (CMEs). Current space
weather prediction tools employ first-principles and/or empirical
models. While these provide useful information, their accuracy,
reliability and forecast window need major improvements. Data
assimilation has the potential to significantly improve model
performance, as it has been successfully done in terrestrial weather
forecast. To allow for the sparsity of satellite observations, however,
a different data assimilation method will be employed. The new model
will start from the Sun with an ensemble of simulations that span
the uncertain observational and model parameters. Using real time and
past observations, the model will strategically down-select to a high
performing subset. Next, the down-selected ensemble will be extended by
varying uncertain parameters and the simulation continued to the next
data assimilation point. The final ensemble will provide a probabilistic
forecast of the space weather impacts. While the concept is simple,
finding the optimal algorithm that produces the best prediction with
minimal uncertainty is a complex and very challenging task that requires
developing, implementing and perfecting novel data assimilation and
uncertainty quantification methods. To make these ensemble simulations
run faster than real time, the most expensive parts of the model
need to run efficiently on the current and future supercomputers,
which employ graphical processing units (GPUs) in addition to the
traditional multi-core CPUs. The main product of this project will be
the Michigan Sun-To-Earth Model with Quantified Uncertainty and Data
Assimilation (MSTEM-QUDA) that will be made available to the space
physics community with an open source license. We will describe the
main concept of the project and our initial progress.
---------------------------------------------------------
Title: Localizing the Source of Type II Emission Around a CME with
the Sun Radio Interferometer Space Experiment (SunRISE)
Authors: Hegedus, A. M.; Kasper, J. C.; Manchester, W.; Lazio, J.;
Romero-Wolf, A.
2020AGUFMSH0090021H Altcode:
The Earth's Ionosphere limits radio measurements on its surface,
blocking out any radiation below 10 MHz. Valuable insight into many
astrophysical processes could be gained by having a radio interferometer
in space to image the low frequency window, which has never been
achieved. One application for such a system is observing type II bursts
that track solar energetic particle acceleration occurring at Coronal
Mass Ejection (CME)-driven shocks. This is one of the primary science
targets for SunRISE, a 6 CubeSat interferometer to circle the Earth
in a GEO graveyard orbit. SunRISE is a NASA Heliophysics Mission of
Opportunity that began Phase B (Formulation) in June 2020, and plans to
launch for a 12-month mission in mid-2023. In this work we present an
update to the data processing and science analysis pipeline for SunRISE
and evaluate its performance in localizing type II bursts around a
simulated CME. <P />To create realistic virtual type II input data,
we employ a 2-temperature MHD simulation of the May 13<SUP>th</SUP>
2005 CME event, and superimpose realistic radio emission models on the
CME-driven shock front, and propagate the signal through the simulated
array. Data cuts based on different plasma parameter thresholds (e.g. de
Hoffman-Teller velocity and angle between shock normal and the upstream
magnetic field) are tested to get the best match to the true recorded
emission. We take into account sources of angular scattering of the
emission such as coronal turbulence. This model type II emission
is then fed to the SunRISE data processing pipeline to ensure that
the array can localize the emission. We include realistic thermal
noise dominated by the galactic background at these low frequencies,
as well as new sources of phase noise from positional uncertainty of
each spacecraft. We test simulated trajectories of SunRISE and image
what the array recovers, comparing it to the virtual input, finding
that SunRISE can resolve the source of type II emission to within
its prescribed goal of 1/3 the CME width. This shows that SunRISE
will significantly advance the scientific community's understanding
of type II burst generation, and consequently, acceleration of solar
energetic particles at CMEs. <P />Complementary abstracts for SunRISE
are presented by J. Kasper, A. Romero-Wolf, and J. Lazio.
---------------------------------------------------------
Title: Applying Machine Learning \to Understanding the Physical
Processes of Solar Flare Onset
Authors: Manchester, W.; Sun, H.; Chen, Y.; Liu, Y.; Jin, M.
2020AGUFMNG0040005M Altcode:
We apply deep learning algorithms (Long Short Term Memory -LSTM) to
train binary strong/weak classification models using active region
parameters provided in HMI/Space-Weather HMI-Active Region Patch
(SHARP) data files. We identify 35 active regions which show a sudden
transition of the prediction score (above 0.7) indicating the likelihood
of an M/X class flare several hours before the event. We examine the
HMI vector magnetogram data for these events to determine if there
are common circumstances and physical processes responsible for the
magnetic energy and magnetic shear that informs the predictions. We
further examine extrapolated nonlinear force-free coronal fields and
Atmospheric Imaging Assembly (AIA) images to determine the structure
of the coronal field and the associated electric currents and free
magnetic energy increase prior to the flaring events. In many cases,
we find development of strong horizontal fields running nearly parallel
to the polarity inversion line to be a precursor to the flaring events.
---------------------------------------------------------
Title: Comparing the best ADAPT realizations from WSA, AWSoM and
AWSoM-R
Authors: Huang, Z.; Sokolov, I.; van der Holst, B.; Toth, G.; Arge,
C. N.; Sachdeva, N.; Jones, S. I.; Manchester, W.; Gombosi, T. I.
2020AGUFMSH0290028H Altcode:
Solar corona models are typically driven by global photospheric
magnetic field maps assembled from magnetograms. Magnetic field maps
derived from different magnetogram sources (e.g. MDI, GONG, etc)
can produce different results when used as boundary conditions. One
of the commonly used synchronic maps is provided by the ADAPT (Air
Force Data Assimilative Photospheric Flux Transport) model, which
makes use of a flux transport model to evolve the regions where there
are no observations. The ADAPT model uses the ensemble least-squares
data assimilation method that account for model and observational
uncertainties and provides 12 different realizations for a given
moment in time. Previous studies have shown the same solar corona
model running with 12 different realizations also provide different
predicted solar wind values at 1 AU. In this presentation, we will
use the ADAPT maps to drive the WSA (Wang-Sheeley-Arge) model, the
AWSoM (Alfven-Wave driven Solar atmosphere Model) and the AWSoM-R
(Alfven-Wave driven Solar atmosphere Model - Realtime) model. The
coronal portion of the WSA model makes use of the coupled potential
field source surface and Schatten current sheet models to derive the
global coronal magnetic field from global maps of the photospheric
field. The model then applies empirical formulas to specify the solar
wind at the outer coronal boundary and a 1D kinematic model to predict
solar wind speed and interplanetary magnetic polarity anywhere in
the inner heliosphere. AWSoM is a physics-based model solving the
MHD equations together with radiative cooling, heat conduction and a
phenomenological Alfven wave turbulence and dissipation model including
wave reflection (proportional to the Alfvén speed gradients) and
turbulent dissipation from the chromosphere to the heliosphere. The
AWSoM-R model uses 1-D field line threads to simulate the region in
the lower chromosphere to speed up the simulations. We will compare
the predicted solar wind values at 1 AU with observations and use the
WSA Prediction Metric developed at NASA Goddard Space Flight Center to
select the best ADAPT map realization(s) for the three models. We will
investigate whether we can improve the prediction capability of the
complex physics-based models like AWSoM and AWSoM-R using the insight
gained from the inexpensive empirical WSA model.
---------------------------------------------------------
Title: Solar Flare Intensity Prediction With Machine Learning Models
Authors: Jiao, Zhenbang; Sun, Hu; Wang, Xiantong; Manchester, Ward;
Gombosi, Tamas; Hero, Alfred; Chen, Yang
2020SpWea..1802440J Altcode: 2019arXiv191206120J
We develop a mixed long short-term memory (LSTM) regression model to
predict the maximum solar flare intensity within a 24-hr time window
0-24, 6-30, 12-36, and 24-48 hr ahead of time using 6, 12, 24, and
48 hr of data (predictors) for each Helioseismic and Magnetic Imager
(HMI) Active Region Patch (HARP). The model makes use of (1) the
Space-Weather HMI Active Region Patch (SHARP) parameters as predictors
and (2) the exact flare intensities instead of class labels recorded
in the Geostationary Operational Environmental Satellites (GOES) data
set, which serves as the source of the response variables. Compared
to solar flare classification, the model offers us more detailed
information about the exact maximum flux level, that is, intensity,
for each occurrence of a flare. We also consider classification
models built on top of the regression model and obtain better results
in solar flare classifications as compared to Chen et al. (2019, <A
href="https://doi.org/10.1029/2019SW002214">https://doi.org/10.1029/2019SW002214</A>).
Our results suggest that the most efficient time period for predicting
the solar activity is within 24 hr before the prediction time using
the SHARP parameters and the LSTM model.
---------------------------------------------------------
Title: Thermodynamic Structure of the Solar Corona: Tomographic
Reconstructions and MHD Modeling
Authors: Lloveras, Diego G.; Vásquez, Alberto M.; Nuevo, Federico
A.; Mac Cormack, Cecilia; Sachdeva, Nishtha; Manchester, Ward; Van
der Holst, Bartholomeus; Frazin, Richard A.
2020SoPh..295...76L Altcode: 2020arXiv200406815L
We carry out a study of the global three-dimensional (3D) structure of
the electron density and temperature of the quiescent inner solar corona
(r <1.25 R<SUB>⊙</SUB>) by means of tomographic reconstructions and
magnetohydrodynamic simulations. We use differential emission measure
tomography (DEMT) and the Alfvén Wave Solar Model (AWSoM), in their
latest versions. Two target rotations were selected from the solar
minimum between Solar Cycles (SCs) 23 and 24 and the declining phase
of SC 24. We report in quantitative detail on the 3D thermodynamic
structure of the core and outer layers of the streamer belt, and
of the high latitude coronal holes (CH), as revealed by the DEMT
analysis. We report on the presence of two types of structures within
the streamer belt, loops with temperature decreasing/increasing with
height (dubbed down/up loops), as reported first in previous DEMT
studies. We also estimate the heating energy flux required at the
coronal base to keep these structures stable, found to be of order
10<SUP>5</SUP>ergcm−<SUP>2</SUP>s−<SUP>1</SUP>, consistently with
previous DEMT and spectroscopic studies. We discuss how these findings
are consistent with coronal dissipation of Alfvén waves. We compare
the 3D results of DEMT and AWSoM in distinct magnetic structures. We
show that the agreement between the products of both techniques is the
best so far, with an overall agreement ≲20 % , depending on the target
rotation and the specific coronal region. In its current implementation
the ASWsoM model cannot reproduce down loops though. Also, in the
source region of the fast and slow components of the solar wind,
the electron density of the AWSoM model increases with latitude,
opposite to the trend observed in DEMT reconstructions.
---------------------------------------------------------
Title: Tuning the Exospace Weather Radio for Stellar Coronal Mass
Ejections
Authors: Alvarado-Gómez, Julián D.; Drake, Jeremy J.; Fraschetti,
Federico; Garraffo, Cecilia; Cohen, Ofer; Vocks, Christian;
Poppenhäger, Katja; Moschou, Sofia P.; Yadav, Rakesh K.; Manchester,
Ward B., IV
2020ApJ...895...47A Altcode: 2020arXiv200405379A
Coronal mass ejections (CMEs) on stars other than the Sun have proven
very difficult to detect. One promising pathway lies in the detection
of type II radio bursts. Their appearance and distinctive properties
are associated with the development of an outward propagating CME-driven
shock. However, dedicated radio searches have not been able to identify
these transient features in other stars. Large Alfvén speeds and
the magnetic suppression of CMEs in active stars have been proposed to
render stellar eruptions "radio-quiet." Employing 3D magnetohydrodynamic
simulations, we study the distribution of the coronal Alfvén speed,
focusing on two cases representative of a young Sun-like star and a
mid-activity M-dwarf (Proxima Centauri). These results are compared with
a standard solar simulation and used to characterize the shock-prone
regions in the stellar corona and wind. Furthermore, using a flux-rope
eruption model, we drive realistic CME events within our M-dwarf
simulation. We consider eruptions with different energies to probe the
regimes of weak and partial CME magnetic confinement. While these CMEs
are able to generate shocks in the corona, those are pushed much farther
out compared to their solar counterparts. This drastically reduces
the resulting type II radio burst frequencies down to the ionospheric
cutoff, which impedes their detection with ground-based instrumentation.
---------------------------------------------------------
Title: Predicting Solar Flares with Machine Learning: Investigating
Solar Cycle Dependence
Authors: Wang, Xiantong; Chen, Yang; Toth, Gabor; Manchester, Ward
B.; Gombosi, Tamas I.; Hero, Alfred O.; Jiao, Zhenbang; Sun, Hu; Jin,
Meng; Liu, Yang
2020ApJ...895....3W Altcode: 2019arXiv191200502W
A deep learning network, long short-term memory (LSTM), is used to
predict whether an active region (AR) will produce a flare of class
Γ in the next 24 hr. We consider Γ to be ≥M (strong flare), ≥C
(medium flare), and ≥A (any flare) class. The essence of using LSTM,
which is a recurrent neural network, is its ability to capture temporal
information on the data samples. The input features are time sequences
of 20 magnetic parameters from the space weather Helioseismic and
Magnetic Imager AR patches. We analyze ARs from 2010 June to 2018
December and their associated flares identified in the Geostationary
Operational Environmental Satellite X-ray flare catalogs. Our results
produce skill scores consistent with recently published results using
LSTMs and are better than the previous results using a single time
input. The skill scores from the model show statistically significant
variation when different years of data are chosen for training and
testing. In particular, 2015-2018 have better true skill statistic and
Heidke skill scores for predicting ≥C medium flares than 2011-2014,
when the difference in flare occurrence rates is properly taken into
account.
---------------------------------------------------------
Title: Using a Higher-order Numerical Scheme to Study the Hall
Magnetic Reconnection
Authors: Yang, Yun; Manchester, Ward B., IV
2020ApJ...892...61Y Altcode:
We use our recently developed higher-order conservation element and
solution element scheme to investigate the evolutionary process of
Hall magnetic reconnection. The purpose of this paper is twofold: (1)
to take advantage of higher-order numerical schemes to capture some fine
structures very well with fewer grid points and reduced computational
cost; (2) to develop a better understanding of the magnetic reconnection
described by Hall MHD; as Birn et al. pointed out, the Hall effect
is a critical ingredient in determining collisionless reconnection
rates in the magnetosphere. The contributions of this paper mainly
include the following: (1) we capture a two-step magnetic reconnection
process and describe the formation mechanism; (2) the simulations
show complex formation and interaction of magnetic islands and we
provide the ways by which the magnetic islands form and disappear;
(3) we find an oscillatory nature of the reconnection and the transfer
of energy from magnetic field to kinetic energy and thermal energy;
(4) we identify the merging process of the central magnetic island
and the outflow region magnetic island.
---------------------------------------------------------
Title: Implementation of the Sun Radio Interferometer Space Experiment
(SunRISE) Mission Concept
Authors: Lazio, J.; Kasper, J. C.; Romero-Wolf, A.; Bastian, T.; Cohen,
C.; Landi, E.; Manchester, W.; Hegedus, A. M.; Schwadron, N.; Sokolov,
I.; Bain, H. M.; Cecconi, B.; Hallinan, G.; Krupar, V.; Maksimovic,
M.; Moschou, S. P.; Zaslavsky, A.; Lux, J. P.; Neilsen, T. L.
2019AGUFMSH31C3328L Altcode:
The Sun Radio Interferometer Space Experiment (SunRISE) would provide
an entirely new view on particle acceleration and transport in the
heliosphere by obtaining spatially and temporally resolved observations
of Decametric-Hectometric (DH, < 15 MHz) Type II and Type III
radio bursts. <P />In order to obtain the required angular resolution,
SunRISE would be a free-flying interferometer. Building on more than 50
years of experience from ground-based very long baseline interferometry
(VLBI), SunRISE would fly six small spacecraft in a supersynchronous
geosynchronous orbit (GEO) in a passive formation. Their orbits
are designed to keep them within approximately 6 km of each other. A
space-based interferometer is required because most of the DH band does
not penetrate the Earth's ionosphere, due to ionospheric absorption. <P
/>Each 6U spacecraft would carry only a single science radio designed
to operate in the DH band. The radio would form spectra on-board,
with pre-selected sub-bands identified for downlink. This science
payload radio would be integrated into a Global Positioning System
(GPS) receiver, allowing precise time to be measured on board the
spacecraft as well. The spacecraft would be independent of each other,
as is the practice for ground-based VLBI arrays. <P />On a regular
basis, both science data and GPS timing would be downlinked. NASA's
Deep Space Network antennas would be used for the downlink, with an
efficient multiple spacecraft per aperture (MSPA) mode enabling the
data from three spacecraft to be downlinked simultaneously. After orbit
determination, the interferometric data processing would form images of
Type II and Type III solar radio bursts and identify the locations of
radio emission relative to the structures of CMEs. <P />SunRISE would
leverage advances in software-defined radios, GPS navigation and timing,
and small spacecraft technologies that have been demonstrated over
the past few years. An Extended Phase A study of the SunRISE mission
concept is scheduled to be completed in 2019 September. <P />Part
of this research was carried out at the Jet Propulsion Laboratory,
California Institute of Technology, under a contract with the National
Aeronautics and Space Administration. Some of the information presented
is pre-decisional and for planning and discussion purposes only.
---------------------------------------------------------
Title: Global Magnetohydrodynamics Simulation of EUV Waves and Shocks
from the X8.2 Eruptive Flare on 2017 September 10
Authors: Jin, M.; Liu, W.; Cheung, C. M. M.; Nitta, N.; DeRosa,
M. L.; Manchester, W.; Ofman, L.; Downs, C.; Petrosian, V.; Omodei,
N.; Moschou, S. P.; Sokolov, I.
2019AGUFMSH32A..01J Altcode:
As one of the largest flare-CME eruptions during solar cycle 24, the
2017 September 10 X8.2 flare event is associated with spectacular
global EUV waves that transverse almost the entire visible solar
disk, a CME with speed > 3000 km/s, which is one of the fastest
CMEs ever recorded, and >100 MeV Gamma-ray emission lasting for
more than 12 hours. All these unique observational features pose new
challenge on current numerical models to reproduce the multi-wavelength
observations. To take this challenge, we simulate the September 10
event using a global MHD model (AWSoM: Alfven Wave Solar Model) within
the Space Weather Modeling Framework and initiate CMEs by Gibson-Low
flux rope. We assess several important observed and physical inputs
(e.g., flux rope properties, polar magnetic field) in the model to
better reproduce the multi-wavelength observations. We find that the
simulated EUV wave morphology and kinematics are sensitive to the
orientation of the initial flux rope introduced to the source active
region. An orientation with the flux-rope axis in the north-south
direction produces the best match to the observations, which suggests
that EUV waves may potentially be used to constrain the flux-rope
geometry for such limb or behind-the-limb eruptions that lack good
magnetic field observations. By further combining with the white
light and radio observations, we demonstrate the flux rope-corona
interaction can greatly impact the early phase shock evolution (e.g.,
geometry and shock parameters) therefore plays a significant role
for particle acceleration near the Sun in this event. By propagating
the CMEs into the heliosphere and beyond the Earth and Mars orbits, we
compare the model results with the in-situ measurements and demonstrate
the importance of input polar magnetic field on the realistic CME
modeling therefore space weather forecasting.
---------------------------------------------------------
Title: Asymmetries in the Martian system
Authors: Regoli, L.; Bougher, S. W.; Manchester, W.
2019AGUFMSM33D3229R Altcode:
The induced Martian magnetosphere is a particularly complex system due
to different dynamic properties that are part of the system. The lack
of a global dynamo and the presence of a relatively tenuous atmosphere
causes the induced magnetosphere to be significantly smaller than
a formal magnetosphere and the boundaries are largely affected by
changes in the upstream conditions. In addition, the presence of strong
localized magnetic fields in the southern hemisphere, commonly referred
to as crustal fields, adds an extra level of complexity, with changes in
the pressure balance through changes in the local magnetic pressure and
localized reconnection constantly changing the magnetic topology of the
induced magnetosphere. This introduces a strong north/south asymmetry
in the system that affects the location of different boundaries as
well as the ionospheric escape, by changing the altitude of the main
ionospheric peak. The dynamical heating of the atmosphere by the solar
radiation also induces asymmetries in the atmospheric densities, which
in turn affect the ion production and subsequent ionospheric escape as
well. These can be north/south asymmetries (depending on the season)
but also dawn/dusk, creating a particular escape pattern that can
be observed in simulations under controlled conditions. We present
results from a coupled set of models with changing parameters based on
a well-defined parameter space in order to study their effect on the
asymmetries present in the Martian system. These parameters include
interplanetary magnetic field (IMF) orientation, solar wind dynamics
pressure, atmospheric dynamics and location of the crustal fields.
---------------------------------------------------------
Title: The Sun Radio Interferometer Space Experiment (SunRISE)
Mission Concept
Authors: Kasper, J. C.; Lazio, J.; Romero-Wolf, A.; Bain, H. M.;
Bastian, T.; Cohen, C.; Landi, E.; Manchester, W.; Hegedus, A. M.;
Schwadron, N.; Sokolov, I.; Cecconi, B.; Hallinan, G.; Krupar, V.;
Maksimovic, M.; Moschou, S. P.; Zaslavsky, A.; Lux, J. P.; Neilsen,
T. L.
2019AGUFMSH33A..02K Altcode:
The Sun Radio Interferometer Space Experiment (SunRISE) would provide
an entirely new view on particle acceleration and transport in the
inner heliosphere by obtaining spatially and temporally resolved
observations of solar Decametric-Hectometric (DH, < 15 MHz) radio
bursts. These bursts are produced by electrons energized near expanding
CMEs (Type II) and released by solar flares (Type III). SunRISE would
track DH bursts from 2 R<SUB>S</SUB> to 20 R<SUB>S</SUB> in order to
achieve two science objectives. The first objective is to discriminate
competing hypotheses for the source mechanism of CME-associated SEPs by
measuring the location of Type II bursts relative to expanding CMEs. By
locating Type II emission relative to the overall structure of CMEs,
SunRISE would reveal where particle acceleration occurs and determine
if specific properties of CMEs lead to DH bursts. The second objective
is to determine if a broad magnetic connection between active regions
and interplanetary space is responsible for the wide longitudinal extent
of some SEPs by imaging the field lines traced by Type III bursts from
active regions through the corona. By tracing the radio emission from
energetic electrons as they travel along magnetic field lines, SunRISE
would reveal the field line topology, and its time variation, from
active regions into interplanetary space. <P />SunRISE would consist
of six 6U small spacecraft in a supersynchronous geosynchronous orbit
(GEO) in a passive formation. Forming a synthetic aperture and observing
at frequencies that cannot be observed on Earth due to ionospheric
absorption, SunRISE would leverage advances in software-defined radios,
GPS navigation and timing, and small spacecraft technologies. These
advances have been flown over the past few years, making this concept
finally affordable and low-risk. <P />An Extended Phase A study
of the SunRISE mission concept is scheduled to be completed in 2019
September. This paper presents a summary of the concept study. <P />Part
of this research was carried out at the Jet Propulsion Laboratory,
California Institute of Technology, under a contract with the National
Aeronautics and Space Administration. Some of the information presented
is pre-decisional and for planning and discussion purposes only.
---------------------------------------------------------
Title: Predicting Solar Flares using Time Sequence Based Machine
Learning Models
Authors: Wang, X.; Toth, G.; Chen, Y.; Manchester, W.; Jiao, Z.; Sun,
H.; Sun, Z.; Hero, A. O.; Gombosi, T. I.
2019AGUFMSH34A..03W Altcode:
In the last few years machine learning methods are becoming popular
for predicting solar flares. We use the Space-weather HMI Active Region
Patches (SHARP) dataset to analyze thousands of active regions' magnetic
field and derived parameters (total unsigned flux, free magnetic
energy, etc) using various machine learning algorithms. In this work
we first use the SHARP summary parameters to predict the maximum flare
intensity in a certain time window through a Long Short-Term Memory
(LSTM) algorithm, which is a particular type of a recurrent neural
network. The dataset we are using contains 3399 active regions from
2010 to 2015. Furthermore, we will use the full vector magnetogram
images to train a combined LSTM and feature extraction convolutional
neural network (CNN). This approach allows capturing more detailed
spatial-temporal features of the magnetic field. Our results show
that using a time sequence to predict the maximum flare intensity can
achieve a better Heidke Skill Score (HSS) than using a single frame
as the input. The HSS for predicting the maximum flare class in the
next 24 hours is about 0.35 for M/X flares and 0.55 for C/M/X flares.
---------------------------------------------------------
Title: Interpreting LSTM Prediction on Solar Flare Eruption with
Time-series Clustering
Authors: Sun, Hu; Manchester, Ward; Jiao, Zhenbang; Wang, Xiantong;
Chen, Yang
2019arXiv191212360S Altcode:
We conduct a post hoc analysis of solar flare predictions made by
a Long Short Term Memory (LSTM) model employing data in the form of
Space-weather HMI Active Region Patches (SHARP) parameters calculated
from data in proximity to the magnetic polarity inversion line where the
flares originate. We train the the LSTM model for binary classification
to provide a prediction score for the probability of M/X class
flares to occur in next hour. We then develop a dimension-reduction
technique to reduce the dimensions of SHARP parameter (LSTM inputs) and
demonstrate the different patterns of SHARP parameters corresponding
to the transition from low to high prediction score. Our work shows
that a subset of SHARP parameters contain the key signals that strong
solar flare eruptions are imminent. The dynamics of these parameters
have a highly uniform trajectory for many events whose LSTM prediction
scores for M/X class flares transition from very low to very high. The
results demonstrate the existence of a few threshold values of SHARP
parameters that when surpassed indicate a high probability of the
eruption of a strong flare. Our method has distilled the knowledge
of solar flare eruption learnt by deep learning model and provides a
more interpretable approximation, which provides physical insight to
processes driving solar flares.
---------------------------------------------------------
Title: Validation of the Alfvén Wave Solar Atmosphere Model (AWSoM)
with Observations from the Low Corona to 1 au
Authors: Sachdeva, Nishtha; van der Holst, Bart; Manchester, Ward B.;
Tóth, Gabor; Chen, Yuxi; Lloveras, Diego G.; Vásquez, Alberto M.;
Lamy, Philippe; Wojak, Julien; Jackson, Bernard V.; Yu, Hsiu-Shan;
Henney, Carl J.
2019ApJ...887...83S Altcode: 2019arXiv191008110S
We perform a validation study of the latest version of the Alfvén
Wave Solar atmosphere Model (AWSoM) within the Space Weather Modeling
Framework. To do so, we compare the simulation results of the model
with a comprehensive suite of observations for Carrington rotations
representative of the solar minimum conditions extending from the
solar corona to the heliosphere up to the Earth. In the low corona
(r < 1.25 {\text{}}{R}<SUB>⊙ </SUB>), we compare with EUV
images from both Solar-Terrestrial Relations Observatory-A/EUVI
and Solar Dynamics Observatory/Atmospheric Imaging Assembly and to
three-dimensional (3D) tomographic reconstructions of the electron
temperature and density based on these same data. We also compare the
model to tomographic reconstructions of the electron density from
Solar and Heliospheric Observatory/Large Angle and Spectrometric
Coronagraph observations (2.55 < r < 6.0{\text{}}{R}<SUB>⊙
</SUB>). In the heliosphere, we compare model predictions of solar wind
speed with velocity reconstructions from InterPlanetary Scintillation
observations. For comparison with observations near the Earth, we use
OMNI data. Our results show that the improved AWSoM model performs
well in quantitative agreement with the observations between the inner
corona and 1 au. The model now reproduces the fast solar wind speed
in the polar regions. Near the Earth, our model shows good agreement
with observations of solar wind velocity, proton temperature, and
density. AWSoM offers an extensive application to study the solar
corona and larger heliosphere in concert with current and future solar
missions as well as being well suited for space weather predictions.
---------------------------------------------------------
Title: Nonequilibrium ionization effects on coronal plasma diagnostics
and elemental abundance measurements
Authors: Shi, T.; Landi, E.; Manchester, W.
2019AGUFMSH11C3402S Altcode:
Plasma diagnostics and elemental abundance measurements are crucial
to help us understand the formation and dynamics of the solar
wind. Here we use a theoretical solar wind model to study the effect
of non-equilibrium ionization (NEI) on plasma diagnostic techniques
applied to line intensities emitted by the fast solar wind. We find
that NEI almost always changes the spectral line intensities with up to
120% difference for the lighter elements and for higher charge states
of Fe even below 1.5 solar radii (Rs). The measured plasma density,
temperature, and differential emission measure (DEM) are only slightly
affected by NEI. However, NEI significantly affects the first ionization
potential (FIP) bias and abundance ratio measurements, producing up to
a factor of 4 error at 1.5 Rs for Mg/Ne, Fe/S, and Ar/Fe ratios when
assuming EI. We conclude that it is very important to consider the
NEI effect when synthesizing spectral line intensities and measuring
the FIP bias and elemental abundance.
---------------------------------------------------------
Title: Improved AWSoM Modeling of the First Two PSP Encounters
Authors: van der Holst, B.; Chandran, B. D. G.; Borovikov, D.;
Manchester, W.; Klein, K. G.; Kasper, J. C.; Case, A. W.; Korreck,
K. E.; Larson, D. E.; Livi, R.; Stevens, M. L.; Whittlesey, P. L.;
Bale, S.; Pulupa, M.; Malaspina, D.; Bonnell, J. W.; Harvey, P.;
Goetz, K.; Dudok de Wit, T.; MacDowall, R. J.
2019AGUFMSH13C3438V Altcode:
NASA's Parker Solar Probe (PSP) has collected data for the first two
encounters. We have modeled the solar corona and inner heliosphere of
these encounters using the Alfvén Wave Solar atmosphere Model (AWSoM,
van der Holst et al. 2014) with GONG-ADAPT magnetograms. AWSoM allows
us to interpret the PSP data in the context of coronal heating via
low-frequency Alfvén wave turbulence with partial wave reflection due
to Alfvén speed gradients. In van der Holst et al. (2019), we made
predictions for the first encounter. In our new simulations we show
how improved partitioning of the wave dissipation to the electron
and anisotropic proton temperatures and better grid design result
in significantly improved comparison with the PSP data. We also show
the simulated distance of PSP to the heliospheric current sheet, the
magnetic connectivity of PSP to the photosphere, and whether PSP was
in the fast or slow wind.
---------------------------------------------------------
Title: Solar Flare Classification and Prediction with Data Science
Authors: Chen, Y.; Manchester, W.; Gombosi, T. I.; Hero, A.; Wang, X.
2019AGUFMSH34A..05C Altcode:
We present our machine learning efforts, which show great promise
towards early predictions of solar flare events. First, we present
a data pre-processing pipeline that is built to extract useful data
from multiple sources -- Geostationary Operational Environmental
Satellites (GOES) and Solar Dynamics Observatory (SDO)/Helioseismic
and Magnetic Imager (HMI) and SDO/Atmospheric Imaging Assembly (AIA)
-- to prepare inputs for machine learning algorithms. Second, we
adopt deep learning algorithms to extract/select features from raw
HMI and AIA data. Third, we train deep learning models that capture
both the spatial and temporal information from HMI magnetogram data
for strong/weak flare classification and for predictions of flare
intensities. Fourth, we show that using the ML-derived features gives
almost as good performance as using active region parameters provided
in HMI/Space-Weather HMI-Active Region Patch (SHARP) data files,
i.e. features manually constructed based on physical principles. Last,
for our strong/weak flare classification model, case studies show a
significant increase in the prediction score around 20 hours before
strong solar flare events, which implies that early precursors appear
at least 20 hours prior to the peak of a flare event.
---------------------------------------------------------
Title: AWSoM Simulation of waves, turbulence and shocks associated
with the September 10, 2014 CME/ICME
Authors: Manchester, W.; van der Holst, B.; Jin, M.; Kasper, J. C.
2019AGUFMSH41A..04M Altcode:
We simulate the September 10, 2014 CME/ICME event and its propagation
to Earth using the Alfven Wave Solar Model (AWSoM) within the Space
Weather Modeling Framework. This fast CME that reached the Earth with an
average transit time of 920 km/s and produced wide spread disturbances
in the corona and heliosphere. We conduct detailed comparisons of this
CME simulation with observations of a range phenomena including waves
with SDO/AIA and coronal shocks with LASCO C2/C3 and the corresponding
type II radio burst. We examine the ICME structure with STEREO/SECCHI
and in situ observations from ACE and Wind, and we examine the impact
on low frequency turbulence observed at 1AU with Wind. Furthermore,
we track the simulated CME-driven shock surfaces and derive the shock
parameters (plasma frequency, theta BN and compression ratio), which
we relate to the observed type II radio burst. We finally discuss the
role of wave reflection, compression and dissipation on the turbulent
energy changes at the shock and in the sheath and ICME ejecta.
---------------------------------------------------------
Title: Validating the Alfven Wave Solar Atmosphere (AWSoM) Model
from the Low Corona to 1 AU
Authors: Sachdeva, N.; van der Holst, B.; Manchester, W.; Toth, G.;
Lloveras, D. G.; Vásquez, A. M.; Lamy, P.; Jackson, B. V.; Henney,
C. J.
2019AGUFMSH51A..04S Altcode:
The coronal/solar wind model, the Alfven Wave Solar atmosphere Model
(AWSoM) a component within the Space Weather Modeling Framework (SWMF)
follows a self-consistent physics-based global description of coronal
heating and solar wind acceleration. AWSoM includes a description
of low-frequency forward and counter-propagating Alfven waves that
non-linearly interact resulting in a turbulent cascade and dissipative
heating. In addition, there are separate temperatures for electrons and
protons with collisional and collisionless heat conduction applied only
to electrons and radiative losses based on the Chianti model. AWSoM
extends from the base of the transition region where the strong
density gradient necessitates self-consistent treatment of Alfven wave
reflection and balanced turbulence. It includes a stochastic heating
model as well as a description of proton parallel and perpendicular
temperatures and kinetic instabilities based on temperature anisotropy
and plasma beta.To validate AWSoM, we model Carrington rotations
representative of solar minimum conditions and compare the simulation
results with a comprehensive suite of observations. In the low corona
(r < 1.25 Rs), we compare with EUV images from both STEREOA/EUVI
and SDO/AIA and to three-dimensional tomographic reconstructions of
the electron temperature and density based on these same data. We
also compare the model to tomographic reconstructions of the electron
density from SOHO/LASCO observations (2.55 < r < 6 Rs). In
the heliosphere, we compare model predictions of solar wind speed
with velocity reconstructions from Interplanetary Scintillation
observations. For comparison with observations near the Earth, we
use OMNI data. Our results show that the AWSoM model performs well
in quantitative agreement with the observations between the inner
corona and 1 AU. In the lower corona, the model and the tomographic
reconstructions agree within 20%-30% on average. The model also
reproduces the fast solar wind speed in the polar regions. Near the
Earth, our model shows good agreement with observations of solar wind
velocity, electron temperature and density. The AWSoM model provides
a comprehensive tool to study the solar corona and larger heliosphere
with current and future solar missions as well as being well suited
for space weather predictions.
---------------------------------------------------------
Title: Identifying Solar Flare Precursors Using Time Series of
SDO/HMI Images and SHARP Parameters
Authors: Chen, Yang; Manchester, Ward B.; Hero, Alfred O.; Toth,
Gabor; DuFumier, Benoit; Zhou, Tian; Wang, Xiantong; Zhu, Haonan;
Sun, Zeyu; Gombosi, Tamas I.
2019SpWea..17.1404C Altcode: 2019arXiv190400125C
In this paper we present several methods to identify precursors that
show great promise for early predictions of solar flare events. A data
preprocessing pipeline is built to extract useful data from multiple
sources, Geostationary Operational Environmental Satellites and Solar
Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI),
to prepare inputs for machine learning algorithms. Two classification
models are presented: classification of flares from quiet times
for active regions and classification of strong versus weak flare
events. We adopt deep learning algorithms to capture both spatial
and temporal information from HMI magnetogram data. Effective feature
extraction and feature selection with raw magnetogram data using deep
learning and statistical algorithms enable us to train classification
models to achieve almost as good performance as using active region
parameters provided in HMI/Space-Weather HMI-Active Region Patch
(SHARP) data files. Case studies show a significant increase in the
prediction score around 20 hr before strong solar flare events.
---------------------------------------------------------
Title: ngGONG: The Next Generation GONG - A New Solar Synoptic
Observational Network
Authors: Hill, Frank; Hammel, Heidi; Martinez-Pillet, Valentin; de
Wijn, A.; Gosain, S.; Burkepile, J.; Henney, C. J.; McAteer, J.; Bain,
H. M.; Manchester, W.; Lin, H.; Roth, M.; Ichimoto, K.; Suematsu, Y.
2019BAAS...51g..74H Altcode: 2019astro2020U..74H
The white paper describes a next-generation GONG, a ground-based
geographically distributed network of instrumentation to continually
observe the Sun. This would provide data for solar magnetic field
research and space weather forecasting, and would extend the time
coverage of helioseismology.
---------------------------------------------------------
Title: Tomography of the Solar Corona with the Wide-Field Imager
for the Parker Solar Probe
Authors: Vásquez, Alberto M.; Frazin, Richard A.; Vourlidas, Angelos;
Manchester, Ward B.; van der Holst, Bart; Howard, Russell A.; Lamy,
Philippe
2019SoPh..294...81V Altcode:
The Wide-field Imager for the Parker Solar Probe (PSP/WISPR) comprises
two telescopes that record white-light total brightness [B ] images of
the solar corona. Their fields of view cover a widely changing range
of heliocentric heights over the 24 highly eccentric orbits planned for
the mission. In this work, the capability of PSP/WISPR data to carry out
tomographic reconstructions of the three-dimensional (3D) distribution
of the coronal electron density is investigated. Based on the precise
orbital information of the mission, B -images for Orbits 1, 12, and 24
are synthesized from a 3D magnetohydrodynamic model of the corona. For
each orbit, the time series of synthetic images is used to carry out a
tomographic reconstruction of the coronal electron density and results
are compared with the model. As the PSP perihelion decreases, the range
of heights that can be tomographically reconstructed progressively
shifts to lower values, and the period required to gather the data
decreases. For Orbit 1 tomographic reconstruction is not possible. For
Orbit 12, tomographic reconstruction is possible in the heliocentric
height range ≈5 -15 R<SUB>⊙</SUB>, over a region spanning up to
≈160<SUP>∘</SUP> in Carrington longitude, with data gathered over
a ≈3.4 day-long period. For Orbit 24, tomographic reconstruction is
possible in the heliocentric height range ≈3 -10 R<SUB>⊙</SUB>, over
a region spanning up to ≈170<SUP>∘</SUP> in Carrington longitude,
with data gathered over a ≈2.8 day-long period.
---------------------------------------------------------
Title: SPECTRUM: Synthetic Spectral Calculations for Global Space
Plasma Modeling
Authors: Szente, J.; Landi, E.; Manchester, W. B., IV; Toth, G.;
van der Holst, B.; Gombosi, T. I.
2019ApJS..242....1S Altcode:
High-resolution spectroscopy is the most accurate tool for measuring
the properties of the solar corona. However, interpreting measured
line intensities and line profiles emitted by the optically thin solar
corona is complicated by line-of-sight (LOS) integration, which leads to
measuring weighted averages of the plasma properties along the LOS. LOS
integration effects can be removed by combining CHIANTI spectral
emissivities with a 3D global model of the solar corona to calculate
the contribution of all structures along the LOS to the measured
intensities. In this paper, we describe SPECTRUM, a postprocessing tool
that can calculate the emission from the optically thin solar corona
by combining 3D magnetohydrodynamic (MHD) space plasma simulation
results with the CHIANTI database. Doppler-shifted, nonthermal line
broadening due to low-frequency Alfvén waves and anisotropic proton
and isotropic electron temperatures can be individually taken into
account during calculations. Synthetic spectral calculations can then
be used for model validation, for interpretation of solar observations,
and for forward modeling purposes. SPECTRUM is implemented within the
Space Weather Modeling Framework (SWMF) and is therefore publicly
available. In this paper, we describe the SPECTRUM module and show
its applications by comparing synthetic spectra using simulation data
by the 3D MHD Alfvén Wave Solar Model with observations done by the
Hinode/Extreme-ultraviolet Imaging Spectrometer during Carrington
rotations 2063 and 2082.
---------------------------------------------------------
Title: Synoptic Studies of the Sun as a Key to Understanding Stellar
Astrospheres
Authors: Martinez Pillet, Valentin; Hill, Frank; Hammel, Heidi B.;
de Wijn, Alfred G.; Gosain, Sanjay; Burkepile, Joan; Henney, Carl;
McAteer, R. T. James; Bain, Hazel; Manchester, Ward; Lin, Haosheng;
Roth, Markus; Ichimoto, Kiyoshi; Suematsu, Yoshinori
2019BAAS...51c.110M Altcode: 2019astro2020T.110M; 2019arXiv190306944M
Ground-based solar observations provide key contextual data (i.e., the
"big picture") to produce a complete description of the only astrosphere
we can study in situ: our Sun's heliosphere. This white paper outlines
the current paradigm for ground-based solar synoptic observations,
and indicates those areas that will benefit from focused attention.
---------------------------------------------------------
Title: Magnetohydrodynamic Simulations for the First and Second
Parker Solar Probe Encounter
Authors: van der Holst, Bart; Chandran, B. D. G.; Borovikov, D.;
Klein, K. G.; Manchester, W. B., IV; Kasper, J. C.
2019shin.confE..49V Altcode:
We examine Alfvén Wave Solar atmosphere Model (AWSoM) simulations
of the first and second Parker Solar Probe (PSP) encounter. AWSoM
allows us to interpret the PSP data in the context of coronal heating
via Alfvén wave turbulence. The coronal heating and acceleration is
addressed via outward-propagating low-frequency Alfvén waves that
are partially reflected by Alfvén speed gradients. The nonlinear
interaction of these counter-propagating waves results in a turbulent
energy cascade. To apportion the wave dissipation to the electron and
anisotropic proton temperatures, we employ an improved version of the
theories of linear wave damping and nonlinear stochastic heating as
described by Chandran et al. 2011. Attention is given to the plasma
mass density, velocity, and magnetic fields, temperature anisotropy,
and wave turbulence. We will also describe the large-scale structures
that PSP might have passed through, for instance whether PSP was in the
fast or slow wind and when PSP crossed the heliospheric current sheet.
---------------------------------------------------------
Title: Applying Machine Learning and Numerical Simulations to
Understanding the Physical Processes of Solar Flare Onset
Authors: Manchester, Ward; Sun, Hu; Chen, Yang; Liu, Yang; Jin, Meng
2019shin.confE.200M Altcode:
We apply deep learning algorithms to train binary strong/weak
classification models using active region parameters provided in
HMI/Space-Weather HMI-Active Region Patch (SHARP) data files. We
identify several active regions which show a sudden transition of
the prediction score indicating near certainty of an M/X class flare
several hours before the event. We examine the HMI vector magnetogram
data for these events to determine if there are common features in
the photospheric magnetic field related to the energy build up and a
possible eruption threshold. We also compare observed magnetic field
to simulations of magnetic flux emergence to identify the physical
processes driving the magnetic evolution toward eruptive behavior.
---------------------------------------------------------
Title: Nonequilibrium ionization effects on coronal plasma diagnostics
and elemental abundance measurements
Authors: Shi, Tong; Landi, Enrico; Manchester, Ward
2019shin.confE..71S Altcode:
Plasma diagnostics and elemental abundance measurements are crucial to
help us understand the formation and dynamics of the solar wind. It
is commonly assumed that the solar wind is in equilibrium ionization
(EI). Here we use a theoretical solar wind model to study whether the
non-equilibrium ionization (NEI) has any effect on the fast solar
wind. We find that the measured plasma density and temperature are
only slightly affected, but NEI systematically shifts the differential
emission measure (DEM) towards lower temperature on all heights. In
addition, NEI significantly affects the first ionization potential
(FIP) bias and abundance measurements. The EI assumption can lead
up to a factor of 4 error at 1.5 solar radii for Mg/Ne, Fe/S, and
Ar/Fe line pairs. Therefore, it is very important to consider the NEI
effect when doing the DEM diagnostics and measuring the FIP bias and
elemental abundance.
---------------------------------------------------------
Title: Validating the Alfven Wave Solar Model (AWSoM) from the lower
corona to 1 AU
Authors: Sachdeva, Nishtha; Manchester, Ward; van der Holst, Bart;
Toth, Gabor; Vasquez, Alberto; Jackson, Bernard; Lloveras, Diego G.;
Mac Cormack, Cecilia; Yu, Hsiu-Shan
2019EGUGA..21.1465S Altcode:
We examine the steady state three-dimensional MHD simulations of the
solar corona carried out with the new version of the Alfven Wave Solar
Model (AWSoM) within the Space Weather Modeling framework (SWMF). AWSoM
addresses the acceleration and heating of the solar corona via the
interaction between counter-propagating Alfven waves. This non-linear
interaction between the outward propagating low-frequency Alfven waves
and those partially reflected by the speed gradients results in a
turbulent energy cascade. The model uses physics-based partitioning
of wave-dissipated heat between isotropic electron and anisotropic
proton temperatures. To validate the AWSoM model, we select rotations
representative of the solar minimum and maximum conditions and compare
our simulation results with a comprehensive suite of observations. We
use three-dimensional tomographic reconstructions of the electron
temperature and density in the inner corona (r < 1.25 Rsun) based
on multi-wavelength extreme ultraviolet images from STEREO/EUVI
and SDO/AIA. For comparison with observations made near the Earth,
we compare the model with OMNI data. At different radial distances
between 20 Rsun and 1 AU, we compare the model with reconstructions
made with Interplanetary Scintillation (IPS) observations. Observations
are compared with the simulated model results of plasma mass density,
velocity, and magnetic fields, temperature anisotropy, and wave
turbulence. Our results at solar minimum show that the improved AWSoM
model performs well in agreement with the observations between inner
corona and 1 AU. In the lower corona the model and the tomographic
reconstructions match within a 20 % accuracy. Near the Earth, our model
shows good agreement with observations of solar wind velocity, electron
temperature and magnetic field. However, the electron density at 1 AU
is overpredicted by the model for the solar minimum simulations. While
this model version is already an improvement over previous predictions,
we plan to validate our model using more Carrington rotations. The AWSoM
model presents an extensive application to study the solar corona and
larger heliosphere in concert with current and future solar missions.
---------------------------------------------------------
Title: Predictions for the First Parker Solar Probe Encounter
Authors: van der Holst, B.; Manchester, W. B., IV; Klein, K. G.;
Kasper, J. C.
2019ApJ...872L..18V Altcode: 2019arXiv190203921V
We examine Alfvén Wave Solar atmosphere Model (AWSoM) predictions
of the first Parker Solar Probe (PSP) encounter. We focus on the 12
day closest approach centered on the first perihelion. AWSoM allows
us to interpret the PSP data in the context of coronal heating via
Alfvén wave turbulence. The coronal heating and acceleration is
addressed via outward-propagating low-frequency Alfvén waves that
are partially reflected by Alfvén speed gradients. The nonlinear
interaction of these counter-propagating waves results in a turbulent
energy cascade. To apportion the wave dissipation to the electron and
anisotropic proton temperatures, we employ the results of the theories
of linear wave damping and nonlinear stochastic heating as described
by Chandran et al. We find that during the first encounter, PSP was
in close proximity to the heliospheric current sheet (HCS) and in the
slow wind. PSP crossed the HCS two times, at 2018 November 3 UT 01:02
and 2018 November 8 UT 19:09, with perihelion occurring on the south of
side of the HCS. We predict the plasma state along the PSP trajectory,
which shows a dominant proton parallel temperature causing the plasma
to be firehose unstable.
---------------------------------------------------------
Title: Global Magnetohydrodynamics Simulation of EUV Waves and Shocks
from the X8.2 Eruptive Flare on 2017 September 10
Authors: Jin, Meng; Liu, Wei; Cheung, Mark; Nitta, Nariaki; Manchester,
Ward; Ofman, Leon; Downs, Cooper; Petrosian, Vahe; Omodei, Nicola
2018csc..confE..66J Altcode:
As one of the largest flare-CME eruptions during solar cycle 24, the
2017 September 10 X8.2 flare event is associated with spectacular
global EUV waves that transverse almost the entire visible solar
disk, a CME with speed > 3000 km/s, which is one of the fastest
CMEs ever recorded, and >100 MeV Gamma-ray emission lasting for
more than 12 hours. All these unique observational features pose new
challenge on current numerical models to reproduce the multi-wavelength
observations. To take this challenge, we simulate the September 10 event
using a global MHD model (AWSoM: Alfven Wave Solar Model) within the
Space Weather Modeling Framework and initiate CMEs by Gibson-Low flux
rope. We conduct detailed comparisons of the synthesized EUV images with
SDO/AIA observations of global EUV waves. We find that the simulated
EUV wave morphology and kinematics are sensitive to the orientation
of the initial flux rope introduced to the source active region. An
orientation with the flux-rope axis in the north-south direction
produces the best match to the observations, which suggests that EUV
waves may potentially be used to constrain the flux-rope geometry for
such limb or behind-the-limb eruptions that lack good magnetic field
observations. We also compare observed and simulated EUV intensities
in multiple AIA channels to perform thermal seismology of the global
corona. Furthermore, we track the 3D CME-driven shock surface in the
simulation and derive the time-varying shock parameters together with
the dynamic magnetic connectivity between the shock and the surface
of the Sun, with which we discuss the role of CME-driven shocks in
the long-duration Gamma-ray events.
---------------------------------------------------------
Title: Multispecies and Multifluid MHD Approaches for the Study of
Ionospheric Escape at Mars
Authors: Regoli, L. H.; Dong, C.; Ma, Y.; Dubinin, E.; Manchester,
W. B.; Bougher, S. W.; Welling, D. T.
2018JGRA..123.7370R Altcode:
A detailed model-model comparison between the results provided by
a multispecies and a multifluid magnetohydrodynamic (MHD) code for
the escape of heavy ions in the Martian-induced magnetosphere is
presented. The results from the simulations are analyzed and compared
against a statistical analysis of the outflow of heavy ions obtained
by the Mars Atmosphere and Volatile EvolutioN/Suprathermal and Thermal
Ion Composition instrument over an extended period of time in order
to estimate the influence of magnetic forces in the ion escape. Both
MHD models are run with the same chemical reactions and ion species
in a steady state mode under idealized solar conditions. Apart from
being able to reproduce the asymmetries observed in the ion escape,
it is found that the multifluid approach provides results that are
closer to those inferred from the ion data. It is also found that the
j × B force term is less effective in accelerating the ions in the
models when compared with the Mars Atmosphere and Volatile EvolutioN
results. Finally, by looking at the contribution of the plume and
the ion escape rates at different distances along the tail with the
multifluid model, it is also found that the escape of heavy ions has
important variabilities along the tail, meaning that the apoapsis
of a spacecraft studying atmospheric escape can affect the estimates
obtained.
---------------------------------------------------------
Title: Global Magnetohydrodynamics Simulation of EUV Waves and Shocks
from the X8.2 Eruptive Flare on 2017 September 10
Authors: Jin, Meng; Liu, Wei; Cheung, Mark; Nitta, Nariaki; Manchester,
Ward; Ofman, Leon; Downs, Cooper; Petrosian, Vahe; Omodei, Nicola
2018shin.confE.207J Altcode:
As one of the largest flare-CME eruptions during solar cycle 24, the
2017 September 10 X8.2 flare event is associated with spectacular
global EUV waves that transverse almost the entire visible solar
disk, a CME with speed > 3000 km/s, which is one of the fastest
CMEs ever recorded, and >100 MeV Gamma-ray emission lasting for
more than 12 hours. All these unique observational features pose new
challenge on current numerical models to reproduce the multi-wavelength
observations. To take this challenge, we simulate the September 10 event
using a global MHD model (AWSoM: Alfven Wave Solar Model) within the
Space Weather Modeling Framework and initiate CMEs by Gibson-Low flux
rope. We conduct detailed comparisons of the synthesized EUV images with
SDO/AIA observations of global EUV waves. We find that the simulated
EUV wave morphology and kinematics are sensitive to the orientation
of the initial flux rope introduced to the source active region. An
orientation with the flux-rope axis in the north-south direction
produces the best match to the observations, which suggests that EUV
waves may potentially be used to constrain the flux-rope geometry for
such limb or behind-the-limb eruptions that lack good magnetic field
observations. We also compare observed and simulated EUV intensities
in multiple AIA channels to perform thermal seismology of the global
corona. Furthermore, we track the 3D CME-driven shock surface in the
simulation and derive the time-varying shock parameters together with
the dynamic magnetic connectivity between the shock and the surface
of the Sun, with which we discuss the role of CME-driven shocks in
the long-duration Gamma-ray events.
---------------------------------------------------------
Title: Coronal magnetic field extrapolation with AWSoM MHD relaxation
Authors: Shi, Tong; Manchester, Ward
2018shin.confE..87S Altcode:
Coronal mass ejections are known to be the major source of disturbances
in the solar wind capable of affecting geomagnetic environments. In
order for accurate predictions of such space weather events, a
data-driven simulation is needed. The first step towards such a
simulation is to extrapolate the magnetic field from the observed
field that is only at the solar surface. In this poster, we present
results of a new code of magnetic field extrapolation with direct
magnetohydrodynamics (MHD) relaxation using the Alfven Wave Solar Model
(AWSoM) in the Space Weather Modeling Framework. The obtained field is
self-consistent with our model and can be used later in time-dependent
simulations without modifications of the equations. We use the Low
and Lou analytical solution to test our results and they reach a good
agreement. We show robustness of our code that the MHD solution can
be stabilized even with noise applied to the magnetic field at the
bottom boundary. This new extrapolation method is then applied to the
magnetic field from the observed data, demonstrating the capabilities
of this code.
---------------------------------------------------------
Title: Extended MHD modeling of the steady solar corona and the
solar wind
Authors: Gombosi, Tamas I.; van der Holst, Bart; Manchester, Ward B.;
Sokolov, Igor V.
2018LRSP...15....4G Altcode: 2018arXiv180700417G
The history and present state of large-scale magnetohydrodynamic
modeling of the solar corona and the solar wind with steady or
quasi-steady coronal physics is reviewed. We put the evolution of
ideas leading to the recognition of the existence of an expanding solar
atmosphere into historical context. The development and main features
of the first generation of global corona and solar wind models are
described in detail. This historical perspective is also applied to
the present suite of global corona and solar wind models. We discuss
the evolution of new ideas and their implementation into numerical
simulation codes. We point out the scientific and computational
challenges facing these models and discuss the ways various groups tried
to overcome these challenges. Next, we discuss the latest, state-of-the
art models and point to the expected next steps in modeling the corona
and the interplanetary medium.
---------------------------------------------------------
Title: Tracking Solar Type II Bursts with the Sun Radio Interferometer
Space Experiment (SunRISE)
Authors: Hegedus, Alexander; Kasper, Justin; Manchester, Ward;
Lazio, Joseph
2018shin.confE.227H Altcode:
The Earth's Ionosphere limits radio measurements on its surface,
blocking out any radiation below 10 MHz. Valuable insight into many
astrophysical processes could be gained by having a radio interferometer
in space to image the low frequency window, which has never been
achieved. One application for such a system is observing type II
bursts tracking solar energetic particle acceleration Coronal Mass
Ejection (CME)-driven shocks. In this work we create a simulated data
processing pipeline for the pathfinder mission SunRISE, a 6 CubeSat
interferometer to circle the Earth in a GEO graveyard orbit, and
evaluate its performance in the task of localizing these type II bursts.
---------------------------------------------------------
Title: Tracking Solar Type II Bursts with Space Based Radio
Interferometers
Authors: Hegedus, Alexander M.; Kasper, Justin C.; Manchester, Ward B.
2018AAS...23240501H Altcode:
The Earth’s Ionosphere limits radio measurements on its surface,
blocking out any radiation below 10 MHz. Valuable insight into many
astrophysical processes could be gained by having a radio interferometer
in space to image the low frequency window for the first time. One
application is observing type II bursts tracking solar energetic
particle acceleration in Coronal Mass Ejections (CMEs). In this work
we create a simulated data processing pipeline for several space based
radio interferometer (SBRI) concepts and evaluate their performance
in the task of localizing these type II bursts.Traditional radio
astronomy software is hard coded to assume an Earth based array. To
circumvent this, we manually calculate the antenna separations and
insert them along with the simulated visibilities into a CASA MS file
for analysis. To create the realest possible virtual input data, we take
a 2-temperature MHD simulation of a CME event, superimpose realistic
radio emission models from the CME-driven shock front, and propagate the
signal through simulated SBRIs. We consider both probabilistic emission
models derived from plasma parameters correlated with type II bursts,
and analytical emission models using plasma emission wave interaction
theory.One proposed SBRI is the pathfinder mission SunRISE, a 6 CubeSat
interferometer to circle the Earth in a GEO graveyard orbit. We test
simulated trajectories of SunRISE and image what the array recovers,
comparing it to the virtual input. An interferometer on the lunar
surface would be a stable alternative that avoids noise sources
that affect orbiting arrays, namely the phase noise from positional
uncertainty and atmospheric 10s-100s kHz noise. Using Digital Elevation
Models from laser altimeter data, we test different sets of locations
on the lunar surface to find near optimal configurations for tracking
type II bursts far from the sun. Custom software is used to model
the response of different array configurations over the lunar year,
combining ephemerides of the sun and moon to correlate the virtual
data. We analyze the pros and cons of all approaches and offer
recommendations for SRBIs that track type II bursts.
---------------------------------------------------------
Title: MHD Modeling of ICMEs and Heliosphere Disturbances with
Application to Space Weather Forecasting
Authors: Manchester, Ward; Jin, Meng; van der Holst, Bart; Sokolov,
Igor
2018tess.conf41103M Altcode:
We examine CME simulation results derived from the Eruptive Event
Generator Gibson-Low EEGGL, which was recently installed at the
Community Coordinated Modeling Center (CCMC). The EEGGL tool allows us
to simulate observed CME events by automatically determining parameters
for the analytical Gibson & Low (GL) flux rope model with data
from synoptic magnetograms and CME coronagraph observations. The CME
simulations are carried out with the Alfven Wave Solar Model (AWSoM),
which allow us to simulate the propagation of ICMEs from the low corona
through the solar wind to 1 AU. We compare model predictions of the
spatial structure and time-evolution of heliospheric disturbances to
in situ observations at 1AU. Attention is given to the ability of the
simulations to reproduce the observed plasma mass density, velocity,
and magnetic fields. We probe the validity and capability of the
numerical models and question their potential to forecast solar wind
conditions and ICME disturbances, while looking forward to the future
capabilities of Solar Probe Plus and Solar Orbiter.
---------------------------------------------------------
Title: Tracking Solar Type II Bursts to .5 AU with Radio
Interferometers on the Lunar Surface
Authors: Hegedus, Alexander Michael; Kasper, Justin Christophe;
Manchester, Ward
2018tess.conf22003H Altcode:
The Earth's Ionosphere limits radio measurements on its surface,
blocking out any radiation below 10 MHz. Valuable insight into various
astrophysical processes could be gained by having a radio interferometer
in space to image this frequency window for the first time. One proposed
incarnation of this is the pathfinder mission SunRISE, an interferometer
to orbit around the Earth in the form of multiple smallsats working
to observe Type II bursts tracking solar energetic particle (SEP)
acceleration in Coronal Mass Ejections (CMEs). An interferometer on
the lunar surface would be a stable alternative that avoids both the
positional uncertainty and 10s-100s kHz noise that would affect orbiting
arrays. Arrays could also be larger, having better resolution at lower
frequencies, allowing us to image Type II bursts and track gradual SEP
events out to .5 AU, far further out than a smaller orbiting array. <P
/>Using Digital Elevation Models partially from Lunar Reconnaissance
Orbiter's Lunar Orbiter Laser Altimeter (LOLA) instrument, we test
different sets of locations on the lunar surface to find near optimal
configurations for planar arrays for tracking Solar Radio Bursts far
from the sun. Custom software is used to model the response of different
array configurations over the lunar year, combining ephemerides of the
sun and moon with LOLA data to correctly correlate the virtual data. To
create the realest possible virtual input data, we take a 2 fluid MHD
simulation of a CME event, and superimpose realistic radio emission
models on top of it, and propagate the signal through various simulated
lunar interferometers. We consider both probabilistic emission models
derived from data cuts of various Type II burst correlated variables,
and analytical emission models using plasma emission wave interaction
theory. We conclude by offering recommendations for the location and
geometry of a future lunar radio interferometer.
---------------------------------------------------------
Title: Global Magnetohydrodynamics Simulation of EUV Waves and Shocks
from the X8.2 Eruptive Flare on 2017 September 10
Authors: Jin, Meng; Liu, Wei; Cheung, Chun Ming Mark; Nitta, Nariaki;
Manchester, Ward; Ofman, Leon; Downs, Cooper; Petrosian, Vahe;
Omodei, Nicola
2018tess.conf31905J Altcode:
As one of the largest flare-CME eruptions during solar cycle 24, the
2017 September 10 X8.2 flare event is associated with spectacular
global EUV waves that transverse almost the entire visible solar
disk, a CME with speed > 3000 km/s, which is one of the fastest
CMEs ever recorded, and >100 MeV Gamma-ray emission lasting for
more than 12 hours. All these unique observational features pose new
challenge on current numerical models to reproduce the multi-wavelength
observations. To take this challenge, we simulate the September 10 event
using a global MHD model (AWSoM: Alfven Wave Solar Model) within the
Space Weather Modeling Framework and initiate CMEs by Gibson-Low flux
rope. We conduct detailed comparisons of the synthesized EUV images with
SDO/AIA observations of global EUV waves. We find that the simulated
EUV wave morphology and kinematics are sensitive to the orientation
of the initial flux rope introduced to the source active region. An
orientation with the flux-rope axis in the north-south direction
produces the best match to the observations, which suggests that EUV
waves may potentially be used to constrain the flux-rope geometry for
such limb or behind-the-limb eruptions that lack good magnetic field
observations. We also compare observed and simulated EUV intensities
in multiple AIA channels to perform thermal seismology of the global
corona. Furthermore, we track the 3D CME-driven shock surface in the
simulation and derive the time-varying shock parameters together with
the dynamic magnetic connectivity between the shock and the surface
of the Sun, with which we discuss the role of CME-driven shocks in
the long-duration Gamma-ray events.
---------------------------------------------------------
Title: The Origin, Early Evolution and Predictability of Solar
Eruptions
Authors: Green, Lucie M.; Török, Tibor; Vršnak, Bojan; Manchester,
Ward; Veronig, Astrid
2018SSRv..214...46G Altcode: 2018arXiv180104608G
Coronal mass ejections (CMEs) were discovered in the early 1970s
when space-borne coronagraphs revealed that eruptions of plasma
are ejected from the Sun. Today, it is known that the Sun produces
eruptive flares, filament eruptions, coronal mass ejections and failed
eruptions; all thought to be due to a release of energy stored in
the coronal magnetic field during its drastic reconfiguration. This
review discusses the observations and physical mechanisms behind this
eruptive activity, with a view to making an assessment of the current
capability of forecasting these events for space weather risk and impact
mitigation. Whilst a wealth of observations exist, and detailed models
have been developed, there still exists a need to draw these approaches
together. In particular more realistic models are encouraged in order
to asses the full range of complexity of the solar atmosphere and the
criteria for which an eruption is formed. From the observational side,
a more detailed understanding of the role of photospheric flows and
reconnection is needed in order to identify the evolutionary path that
ultimately means a magnetic structure will erupt.
---------------------------------------------------------
Title: Magnetic field extrapolation with MHD relaxation using AWSoM
Authors: Shi, T.; Manchester, W.; Landi, E.
2017AGUFMSH13A2458S Altcode:
Coronal mass ejections are known to be the major source of disturbances
in the solar wind capable of affecting geomagnetic environments. In
order for accurate predictions of such space weather events,
a data-driven simulation is needed. The first step towards such a
simulation is to extrapolate the magnetic field from the observed field
that is only at the solar surface. Here we present results of a new
code of magnetic field extrapolation with direct magnetohydrodynamics
(MHD) relaxation using the Alfvén Wave Solar Model (AWSoM) in the Space
Weather Modeling Framework. The obtained field is self-consistent with
our model and can be used later in time-dependent simulations without
modifications of the equations. We use the Low and Lou analytical
solution to test our results and they reach a good agreement. We also
extrapolate the magnetic field from the observed data. We then specify
the active region corona field with this extrapolation result in the
AWSoM model and self-consistently calculate the temperature of the
active region loops with Alfvén wave dissipation. Multi-wavelength
images are also synthesized.
---------------------------------------------------------
Title: A Spectroscopic Study of the Energy Deposition in the Low
Corona: Connecting Global Modeling to Observations
Authors: Szente, J.; Landi, E.; Toth, G.; Manchester, W.; van der
Holst, B.; Gombosi, T. I.
2017AGUFMSH41C..06S Altcode:
We are looking for signatures of coronal heating process using a
physically consistent 3D MHD model of the global corona. Our approach is
based on the Alfvén Wave Solar atmosphere Model (AWSoM), with a domain
ranging from the upper chromosphere (50,000K) to the outer corona,
and the solar wind is self-consistently heated and accelerated by the
dissipation of low-frequency Alfvén waves. Taking into account separate
electron and anisotropic proton heating, we model the coronal plasma
at the same time and location as observed by Hinode/EIS, and calculate
the synthetic spectra that we compare with the observations. With
the obtained synthetic spectra, we are able to directly calculate
line intensities, line width, thermal and nonthermal motions, line
centroids, Doppler shift distributions and compare our predictions
to real measurements. Our results directly test the extent to which
Alfvénic heating is present in the low corona.
---------------------------------------------------------
Title: Tomographic Validation of the AWSoM Model of the Inner Corona
During Solar Minima
Authors: Manchester, W.; Vásquez, A. M.; Lloveras, D. G.; Mac Cormack,
C.; Nuevo, F.; Lopez-Fuentes, M.; Frazin, R. A.; van der Holst, B.;
Landi, E.; Gombosi, T. I.
2017AGUFMSH51C2512M Altcode:
Continuous improvement of MHD three-dimensional (3D) models of the
global solar corona, such as the Alfven Wave Solar Model (AWSoM) of
the Space Weather Modeling Framework (SWMF), requires testing their
ability to reproduce observational constraints at a global scale. To
that end, solar rotational tomography based on EUV image time-series
can be used to reconstruct the 3D distribution of the electron density
and temperature in the inner solar corona (r < 1.25 Rsun). The
tomographic results, combined with a global coronal magnetic model, can
further provide constraints on the energy input flux required at the
coronal base to maintain stable structures. In this work, tomographic
reconstructions are used to validate steady-state 3D MHD simulations
of the inner corona using the latest version of the AWSoM model. We
perform the study for selected rotations representative of solar
minimum conditions, when the global structure of the corona is more
axisymmetric. We analyse in particular the ability of the MHD simulation
to match the tomographic results across the boundary region between the
equatorial streamer belt and the surrounding coronal holes. The region
is of particular interest as the plasma flow from that zone is thought
to be related to the origin of the slow component of the solar wind.
---------------------------------------------------------
Title: Solar Atmosphere to Earth's Surface: Long Lead Time dB/dt
Predictions with the Space Weather Modeling Framework
Authors: Welling, D. T.; Manchester, W.; Savani, N.; Sokolov, I.;
van der Holst, B.; Jin, M.; Toth, G.; Liemohn, M. W.; Gombosi, T. I.
2017AGUFMSH34B..05W Altcode:
The future of space weather prediction depends on the community's
ability to predict L1 values from observations of the solar
atmosphere, which can yield hours of lead time. While both
empirical and physics-based L1 forecast methods exist, it is not
yet known if this nascent capability can translate to skilled
dB/dt forecasts at the Earth's surface. This paper shows results
for the first forecast-quality, solar-atmosphere-to-Earth's-surface
dB/dt predictions. Two methods are used to predict solar wind and
IMF conditions at L1 for several real-world coronal mass ejection
events. The first method is an empirical and observationally based
system to estimate the plasma characteristics. The magnetic field
predictions are based on the Bz4Cast system which assumes that the
CME has a cylindrical flux rope geometry locally around Earth's
trajectory. The remaining plasma parameters of density, temperature
and velocity are estimated from white-light coronagraphs via a variety
of triangulation methods and forward based modelling. The second is
a first-principles-based approach that combines the Eruptive Event
Generator using Gibson-Low configuration (EEGGL) model with the Alfven
Wave Solar Model (AWSoM). EEGGL specifies parameters for the Gibson-Low
flux rope such that it erupts, driving a CME in the coronal model
that reproduces coronagraph observations and propagates to 1AU. The
resulting solar wind predictions are used to drive the operational
Space Weather Modeling Framework (SWMF) for geospace. Following the
configuration used by NOAA's Space Weather Prediction Center, this
setup couples the BATS-R-US global magnetohydromagnetic model to the
Rice Convection Model (RCM) ring current model and a height-integrated
ionosphere electrodynamics model. The long lead time predictions
of dB/dt are compared to model results that are driven by L1 solar
wind observations. Both are compared to real-world observations from
surface magnetometers at a variety of geomagnetic latitudes. Metrics
are calculated to examine how the simulated solar wind drivers
impact forecast skill. These results illustrate the current state
of long-lead-time forecasting and the promise of this technology for
operational use.
---------------------------------------------------------
Title: The Interaction of Coronal Mass Ejections with Alfvenic
Turbulence
Authors: Manchester, W.; van der Holst, B.
2017AGUFMSH42B..06M Altcode:
We provide a first attempt to understand the interaction between Alfven
wave turbulence, kinetic instabilities and temperature anisotropies
in the environment of a fast coronal mass ejection (CME). The impact
of a fast CME on the solar corona causes turbulent energy, thermal
energy and dissipative heating to increase by orders of magnitude, and
produces conditions suitable for a host of kinetic instabilities. We
study these CME-induced effects with the recently developed Alfven Wave
Solar Model, with which we are able to self-consistently simulate the
turbulent energy transport and dissipation as well as isotropic electron
heating and anisotropic proton heating. Furthermore, the model also
offers the capability to address the effects of firehose, mirror mode,
and cyclotron kinetic instabilities on proton energy partitioning,
all in a global-scale numerical simulation. We find turbulent energy
greatly enhanced in the CME sheath, strong wave reflection at the
shock, which leads to wave dissipation rates increasing by more than
a factor of 100. In contrast, wave energy is greatly diminished
by adiabatic expansion in the flux rope. Finally, we find proton
temperature anisotropies are limited by kinetic instabilities to a
level consistent with solar wind observations.
---------------------------------------------------------
Title: The Sun Radio Imaging Space Experiment (SunRISE) Mission
Authors: Kasper, J. C.; Lazio, J.; Alibay, F.; Amiri, N.; Bastian,
T.; Cohen, C.; Landi, E.; Hegedus, A. M.; Maksimovic, M.; Manchester,
W.; Reinard, A.; Schwadron, N.; Cecconi, B.; Hallinan, G.; Krupar, V.
2017AGUFMSH41B2760K Altcode:
Radio emission from coronal mass ejections (CMEs) is a direct tracer
of particle acceleration in the inner heliosphere and potential
magnetic connections from the lower solar corona to the larger
heliosphere. Energized electrons excite Langmuir waves, which then
convert into intense radio emission at the local plasma frequency,
with the most intense acceleration thought to occur within 20 R_S. The
radio emission from CMEs is quite strong such that only a relatively
small number of antennas is required to detect and map it, but many
aspects of this particle acceleration and transport remain poorly
constrained. Ground-based arrays would be quite capable of tracking
the radio emission associated with CMEs, but absorption by the Earth's
ionosphere limits the frequency coverage of ground-based arrays (nu >
15 MHz), which in turn limits the range of solar distances over which
they can track the radio emission (< 3 R_S). The state-of-the-art
for tracking such emission from space is defined by single antennas
(Wind/WAVES, Stereo/SWAVES), in which the tracking is accomplished by
assuming a frequency-to-density mapping; there has been some success
in triangulating the emission between the spacecraft, but considerable
uncertainties remain. We describe the Sun Radio Imaging Space Experiment
(SunRISE) mission concept: A constellation of small spacecraft in a
geostationary graveyard orbit designed to localize and track radio
emissions in the inner heliosphere. Each spacecraft would carry a
receiving system for observations below 25 MHz, and SunRISE would
produce the first images of CMEs more than a few solar radii from
the Sun. Part of this research was carried out at the Jet Propulsion
Laboratory, California Institute of Technology, under a contract with
the National Aeronautics and Space Administration.
---------------------------------------------------------
Title: Two-way Effects of an ICME Event at Mars
Authors: Regoli, L.; Fang, X.; Dong, C.; Tenishev, V.; Lee, Y.;
Bougher, S. W.; Manchester, W.
2017AGUFMSM33B2644R Altcode:
The influence of enhanced solar activity on planetary magnetospheres
is a subject of great interest. At Mars, given the small size
of its induced magnetosphere compared to the size of the planet,
a gravitationally bound oxygen corona extends above the bow shock
upstream of the planet. These oxygen atoms can be ionized by different
processes and precipitate into the upper atmosphere of Mars. When they
deposit their energy, they heat the thermosphere locally according to
the path they follow which is mainly determined by the magnetic field
configuration within the induced magnetosphere. While previous studies
have investigated the energy deposition during interplanetary coronal
mass ejection (ICME) events, this study focuses on the effect that an
enhanced thermosphere/ionosphere has in the surrounding environment,
including the increased escape. For this, we use a combination of
models comprising a global circulation model of the Martian atmosphere
(MGITM), a 3D model of the hot oxygen corona (AMPS), a multi-fluid
magnetohydrodynamics (MHD) model of the induced magnetosphere and a
test particle code (MCPIT) to propagate the precipitating ions into
the exobase.
---------------------------------------------------------
Title: The Physical Processes of CME/ICME Evolution
Authors: Manchester, Ward; Kilpua, Emilia K. J.; Liu, Ying D.; Lugaz,
Noé; Riley, Pete; Török, Tibor; Vršnak, Bojan
2017SSRv..212.1159M Altcode: 2017SSRv..tmp...90M
As observed in Thomson-scattered white light, coronal mass ejections
(CMEs) are manifest as large-scale expulsions of plasma magnetically
driven from the corona in the most energetic eruptions from the
Sun. It remains a tantalizing mystery as to how these erupting magnetic
fields evolve to form the complex structures we observe in the solar
wind at Earth. Here, we strive to provide a fresh perspective on the
post-eruption and interplanetary evolution of CMEs, focusing on the
physical processes that define the many complex interactions of the
ejected plasma with its surroundings as it departs the corona and
propagates through the heliosphere. We summarize the ways CMEs and
their interplanetary CMEs (ICMEs) are rotated, reconfigured, deformed,
deflected, decelerated and disguised during their journey through the
solar wind. This study then leads to consideration of how structures
originating in coronal eruptions can be connected to their far removed
interplanetary counterparts. Given that ICMEs are the drivers of most
geomagnetic storms (and the sole driver of extreme storms), this work
provides a guide to the processes that must be considered in making
space weather forecasts from remote observations of the corona.
---------------------------------------------------------
Title: Eruptive event generator based on the Gibson-Low magnetic
configuration
Authors: Borovikov, D.; Sokolov, I. V.; Manchester, W. B.; Jin, M.;
Gombosi, T. I.
2017JGRA..122.7979B Altcode: 2017arXiv170801635B
Coronal mass ejections (CMEs), a kind of energetic solar eruptions,
are an integral subject of space weather research. Numerical
magnetohydrodynamic (MHD) modeling, which requires powerful
computational resources, is one of the primary means of studying the
phenomenon. With increasing accessibility of such resources, grows the
demand for user-friendly tools that would facilitate the process of
simulating CMEs for scientific and operational purposes. The Eruptive
Event Generator based on Gibson-Low flux rope (EEGGL), a new publicly
available computational model presented in this paper, is an effort to
meet this demand. EEGGL allows one to compute the parameters of a model
flux rope driving a CME via an intuitive graphical user interface. We
provide a brief overview of the physical principles behind EEGGL and its
functionality. Ways toward future improvements of the tool are outlined.
---------------------------------------------------------
Title: Spectral Analysis of Heating Processes in the Alfvén Wave
Driven Global Corona Model
Authors: Szente, Judit; Toth, Gabor; Landi, Enrico; Manchester, Ward;
van der Holst, Bart; Gombosi, Tamas
2017shin.confE..78S Altcode:
Among numerous theories explaining the existence of the hot solar
corona and continuous solar wind, one of the most successful one is
based on wave heating. This approach describes Alfvén waves traveling
along the magnetic field lines carrying sufficient energy to heat the
corona and accelerate the solar wind. The wave energy is deposited
through turbulent dissipation, which leaves identifiable traces in the
plasma. Spectral observations have suggested the existence of wave
heating: via the decrease of non-thermal spectral line broadening,
and via charge state ratios of specific minor-ions reflecting the
heating history of the solar wind plasma. We determine the extent
to which Alfvén-waves drive the solar corona using a combination of
spectral modeling and observational techniques. <P />In this study,
we reevaluate observational evidence of the coronal heating process:
we simulate observations of the global corona and its spectral line
emission with the Alfvén Wave Solar Model (AWSoM) and compare the
synthetic data with observations.
---------------------------------------------------------
Title: Simulating the Initiation and Liftoff Phases of CMEs
Authors: Shi, Tong; Manchester, Ward; Landi, Enrico
2017shin.confE..15S Altcode:
Coronal mass ejections (CMEs) are known to be the major source of
disturbances in the solar wind capable of affecting geomagnetic
environments. However, we are currently lacking in key information
during the early stage of the CMEs, including the nature of the
triggering mechanisms, that we are unable to accurately predict CME
onset, initial propagation, and possible impact on the planetary
systems. Here we will present preliminary results on a data-driven
CME simulation with the Space Weather Modeling Framework. Performing
such a simulation involves several steps: extrapolating the coronal
magnetic field from active region vector magnetogram observations
with nonlinear force free field model; using this field as the initial
condition for a steady state simulation; and then driving the eruption
by applying converging motion at the polarity inversion line at the
lower boundary. This data-driven simulation will help us to support
or restrict the mechanisms that provide reliable magnetic, kinematics,
and thermal properties of a CME in its early stage, and is a required
first step towards an accurate space weather forecast.
---------------------------------------------------------
Title: The Sun Radio Imaging Space Experiment (SunRISE) Mission
Authors: Lazio, Joseph; Kasper, Justin; Maksimovic, Milan; Alibay,
Farah; Amiri, Nikta; Bastian, Tim; Cohen, Christina; Landi, Enrico;
Manchester, Ward; Reinard, Alysha; Schwadron, Nathan; Cecconi,
Baptiste; Hallinan, Gregg; Hegedus, Alex; Krupar, Vratislav; Zaslavsky,
Arnaud
2017EGUGA..19.5580L Altcode:
Radio emission from coronal mass ejections (CMEs) is a direct tracer
of particle acceleration in the inner heliosphere and potential
magnetic connections from the lower solar corona to the larger
heliosphere. Energized electrons excite Langmuir waves, which then
convert into intense radio emission at the local plasma frequency,
with the most intense acceleration thought to occur within 20 RS. The
radio emission from CMEs is quite strong such that only a relatively
small number of antennas is required to detect and map it, but many
aspects of this particle acceleration and transport remain poorly
constrained. Ground-based arrays would be quite capable of tracking
the radio emission associated with CMEs, but absorption by the Earth's
ionosphere limits the frequency coverage of ground-based arrays (ν
≳ 15 MHz), which in turn limits the range of solar distances over
which they can track the radio emission (≲ 3RS). The state-of-the-art
for tracking such emission from space is defined by single antennas
(Wind/WAVES, Stereo/SWAVES), in which the tracking is accomplished by
assuming a frequency-to-density mapping; there has been some success
in triangulating the emission between the spacecraft, but considerable
uncertainties remain. We describe the Sun Radio Imaging Space Experiment
(SunRISE) mission concept: A constellation of small spacecraft in a
geostationary graveyard orbit designed to localize and track radio
emissions in the inner heliosphere. Each spacecraft would carry a
receiving system for observations below 25 MHz, and SunRISE would
produce the first images of CMEs more than a few solar radii from
the Sun. Part of this research was carried out at the Jet Propulsion
Laboratory, California Institute of Technology, under a contract with
the National Aeronautics and Space Administration.
---------------------------------------------------------
Title: Coronal Jets Simulated with the Global Alfvén Wave Solar Model
Authors: Szente, J.; Toth, G.; Manchester, W. B., IV; van der Holst,
B.; Landi, E.; Gombosi, T. I.; DeVore, C. R.; Antiochos, S. K.
2017ApJ...834..123S Altcode:
This paper describes a numerical modeling study of coronal jets to
understand their effects on the global corona and their contribution
to the solar wind. We implement jets into a well-established
three-dimensional, two-temperature magnetohydrodynamic (MHD) solar
corona model employing Alfvén-wave dissipation to produce a realistic
solar-wind background. The jets are produced by positioning a compact
magnetic dipole under the solar surface and rotating the boundary plasma
around the dipole's magnetic axis. The moving plasma drags the magnetic
field lines along with it, ultimately leading to a reconnection-driven
jet similar to that described by Pariat et al. We compare line-of-sight
synthetic images to multiple jet observations at EUV and X-ray
bands, and find very close matches in terms of physical structure,
dynamics, and emission. Key contributors to this agreement are the
greatly enhanced plasma density and temperature in our jets compared
to previous models. These enhancements arise from the comprehensive
thermodynamic model that we use and, also, our inclusion of a dense
chromosphere at the base of our jet-generating regions. We further
find that the large-scale corona is affected significantly by the
outwardly propagating torsional Alfvén waves generated by our polar
jet, across 40° in latitude and out to 24 R<SUB>⊙</SUB>. We estimate
that polar jets contribute only a few percent to the steady-state
solar-wind energy outflow.
---------------------------------------------------------
Title: Anatomy of Depleted Interplanetary Coronal Mass Ejections
Authors: Kocher, M.; Lepri, S. T.; Landi, E.; Zhao, L.; Manchester,
W. B., IV
2017ApJ...834..147K Altcode:
We report a subset of interplanetary coronal mass ejections (ICMEs)
containing distinct periods of anomalous heavy-ion charge state
composition and peculiar ion thermal properties measured by ACE/SWICS
from 1998 to 2011. We label them “depleted ICMEs,” identified
by the presence of intervals where C<SUP>6+</SUP>/C<SUP>5+</SUP>
and O<SUP>7+</SUP>/O<SUP>6+</SUP> depart from the direct correlation
expected after their freeze-in heights. These anomalous intervals within
the depleted ICMEs are referred to as “Depletion Regions.” We find
that a depleted ICME would be indistinguishable from all other ICMEs in
the absence of the Depletion Region, which has the defining property
of significantly low abundances of fully charged species of helium,
carbon, oxygen, and nitrogen. Similar anomalies in the slow solar wind
were discussed by Zhao et al. We explore two possibilities for the
source of the Depletion Region associated with magnetic reconnection
in the tail of a CME, using CME simulations of the evolution of two
Earth-bound CMEs described by Manchester et al.
---------------------------------------------------------
Title: Chromosphere to 1 AU Simulation of the 2011 March 7th Event:
A Comprehensive Study of Coronal Mass Ejection Propagation
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Sokolov, I.;
Tóth, G.; Vourlidas, A.; de Koning, C. A.; Gombosi, T. I.
2017ApJ...834..172J Altcode: 2016arXiv161108897J
We perform and analyze the results of a global magnetohydrodynamic
simulation of the fast coronal mass ejection (CME) that occurred
on 2011 March 7. The simulation is made using the newly developed
Alfvén Wave Solar Model (AWSoM), which describes the background
solar wind starting from the upper chromosphere and extends to
24 R<SUB>⊙</SUB>. Coupling AWSoM to an inner heliosphere model
with the Space Weather Modeling Framework extends the total domain
beyond the orbit of Earth. Physical processes included in the model
are multi-species thermodynamics, electron heat conduction (both
collisional and collisionless formulations), optically thin radiative
cooling, and Alfvén-wave turbulence that accelerates and heats the
solar wind. The Alfvén-wave description is physically self-consistent,
including non-Wentzel-Kramers-Brillouin reflection and physics-based
apportioning of turbulent dissipative heating to both electrons and
protons. Within this model, we initiate the CME by using the Gibson-Low
analytical flux rope model and follow its evolution for days, in which
time it propagates beyond STEREO A. A detailed comparison study is
performed using remote as well as in situ observations. Although the
flux rope structure is not compared directly due to lack of relevant
ejecta observation at 1 au in this event, our results show that the
new model can reproduce many of the observed features near the Sun
(e.g., CME-driven extreme ultraviolet [EUV] waves, deflection of the
flux rope from the coronal hole, “double-front” in the white light
images) and in the heliosphere (e.g., shock propagation direction,
shock properties at STEREO A).
---------------------------------------------------------
Title: Data-constrained Coronal Mass Ejections in a Global
Magnetohydrodynamics Model
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Sokolov, I.;
Tóth, G.; Mullinix, R. E.; Taktakishvili, A.; Chulaki, A.; Gombosi,
T. I.
2017ApJ...834..173J Altcode: 2016arXiv160505360J
We present a first-principles-based coronal mass ejection (CME)
model suitable for both scientific and operational purposes by
combining a global magnetohydrodynamics (MHD) solar wind model with
a flux-rope-driven CME model. Realistic CME events are simulated
self-consistently with high fidelity and forecasting capability by
constraining initial flux rope parameters with observational data from
GONG, SOHO/LASCO, and STEREO/COR. We automate this process so that
minimum manual intervention is required in specifying the CME initial
state. With the newly developed data-driven Eruptive Event Generator
using Gibson-Low configuration, we present a method to derive Gibson-Low
flux rope parameters through a handful of observational quantities so
that the modeled CMEs can propagate with the desired CME speeds near
the Sun. A test result with CMEs launched with different Carrington
rotation magnetograms is shown. Our study shows a promising result
for using the first-principles-based MHD global model as a forecasting
tool, which is capable of predicting the CME direction of propagation,
arrival time, and ICME magnetic field at 1 au (see the companion paper
by Jin et al. 2016a).
---------------------------------------------------------
Title: The Sun Radio Interferometer Space Experiment (SunRISE)
Authors: Alibay, F.; Lazio, J.; Kasper, J. C.; Amiri, N.; Bastian,
T.; Cohen, C.; Landi, E.; Manchester, W.; Reinard, A.; Schwadron, N.;
Hegedus, A. M.; Maksimovic, M.; Zaslavsky, A.; Cecconi, B.; Hallinan,
G.; Krupar, V.
2016AGUFMSH41B2540A Altcode:
Radio emission from coronal mass ejections (CMEs) is a direct tracer
of the particle acceleration in the inner heliosphere and potential
magnetic connections from the lower solar corona to the larger
heliosphere. However, many aspects of this particle acceleration
remain poorly constrained. The radio emission from CMEs is quite
strong such that only a relatively small number of antennas is
required to map it. However, the state-of-the-art for tracking
such emission is only defined by single antennas (Wind/WAVES,
Stereo/SWAVES) in which the tracking is accomplished by assuming
a frequency-to-density mapping. These are limited to tracking CMEs
to only a few solar radii before the frequencies of radio emission
drop below the Earth's ionospheric cutoff. Triangulation between the
STEREO/SWAVES and Wind/WAVES instruments have provided some initial
constraints on particle acceleration sites at larger distances (lower
frequencies), but the uncertainties remain considerable. We present
the Sun Radio Imaging Space Experiment (SunRISE) mission concept:
a space-based array designed to localize such radio emissions. This
low-cost constellation is composed of small spacecraft placed in a
geostationary graveyard orbit, each carrying an HF radio receiver. In
this concept, each spacecraft would perform concurrent observations
below 25 MHz, which would then be correlated on the ground to produce
the first images of CMEs more than a few solar radii from the Sun. Part
of this research was carried out at the Jet Propulsion Laboratory,
California Institute of Technology, under a contract with the National
Aeronautics and Space Administration.
---------------------------------------------------------
Title: Studying the thermodynamics of coronal jets through modeling-
and observational diagnostics techniques
Authors: Szente, J.; Manchester, W.; Landi, E.; Toth, G.; van der
Holst, B.; Gombosi, T. I.; DeVore, C. R.; Antiochos, S. K.
2016AGUFMSH21E2577S Altcode:
We present a comprehensive study of simulated and observed coronal jets
using EUV and soft X-ray narrow-band images and EUV high resolution
spectra. The goal of our study is to understand the thermodynamics
and time evolution of jets and their impact on the coronal plasma. We
simulate jets with a full 3D MHD coronal model with separate electron
and proton temperatures and heating due to Alfvén wave turbulence. Due
to the fast dynamics of the small-scale eruptive reconnections at the
footpoint of the jet, it is essential to undertake this effort with a
model with separate electron and proton temperatures to interpret the
observed signatures in EUV and soft X-ray bands. The obtained synthetic
images are compared to observations done by the instrumentations of
SDO, STEREO and Hinode space crafts. The turbulence in this model is
ideally suited to analyze the spectroscopic signatures, such as line
broadening. The 3-hour long simulation of jets interacting with the
global solar corona shows plasma responses potentially being observed
with the upcoming Solar Probe Plus mission.
---------------------------------------------------------
Title: New Capabilities for Adaptive Mesh Simulation Use within
FORWARD
Authors: Mathews, N.; Flyer, N.; Gibson, S. E.; Kucera, T. A.;
Manchester, W.
2016AGUFMSM32A..05M Altcode:
The multiscale nature of the solar corona can pose challenges to
numerical simulations. Adaptive meshes are often used to resolve
fine-scale structures, such as the chromospheric-coronal interface
found in prominences and the transition region as a whole. FORWARD is
a SolarSoft IDL package designed as a community resource for creating
a broad range of synthetic coronal observables from numerical models
and comparing them to data. However, to date its interface with
numerical simulations has been limited to regular grids. We will
present a new adaptive-grid interface to FORWARD that will enable
efficient synthesis of solar observations. This is accomplished
through the use of hierarchical IDL structures designed to enable
finding nearest-neighbor points quickly for non-uniform grids. This
facilitates line-of-sight integrations that can adapt to the unequally
spaced mesh. We will demonstrate this capability for the Alfven-Wave
driven SOlar wind Model (AWSOM), part of the Space Weather Modeling
Framework (SWMF). In addition, we will use it in the context of a
prominence-cavity model, highlighting new capabilities in FORWARD that
allow treatment of continuum absorbtion as well as EUV line emission
via dual populations (chromosphere-corona).
---------------------------------------------------------
Title: Forecasting CMEs at 1AU with a Flux Rope-Driven Model
Authors: Manchester, W.; Jin, M.; van der Holst, B.; Toth, G.;
Mullinix, R.; Taktakishvili, A.; Chulaki, A.; Gombosi, T. I.
2016AGUFMSH11C2249M Altcode:
Until recently, operational models of coronal mass ejection (CME)
propagation omitted magnetic drivers and imposed CMEs with field-free
flows. While capable of predicting the arrival times of solar wind
disturbances, such models are incapable of predicting the magnetic
ejecta of a CME, which is the fundamental driver of large geomagnetic
storms. Here, we report on a significant advancement in the development
and delivery of a magnetic flux rope-driven operational CME model
Eruptive Event Generator Gibson-Low EEGGL that was recently installed
at the Community Coordinated Modeling Center (CCMC). This new model
simulates the propagation of CMEs from Sun to 1AU by combining the
analytical Gibson & Low (GL) flux rope model with the state-of-art
Alfven Wave Solar Model. Using synoptic magnetcogram and coronagraph
observations, the model can predict the long-term evolution of the CME
magnetic fields in interplanetary space. Following the work of Jin et
al. (2016), we examine case studies of CMEs at 1 AU to illustrate the
capabilities and limitations of this space weather forecasting tool.
---------------------------------------------------------
Title: Data Constrained Coronal Mass Ejections in A Global
Magnetohydrodynamics Model
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Sokolov, I.;
Toth, G.; Mullinix, R. E.; Taktakishvili, A.; Chulaki, A.; Gombosi,
T. I.
2016usc..confE.120J Altcode:
We present a first-principles-based coronal mass ejection (CME)
model suitable for both scientific and operational purposes by
combining a global magnetohydrodynamics (MHD) solar wind model with
a flux rope-driven CME model. Realistic CME events are simulated
self-consistently with high fidelity and forecasting capability by
constraining initial flux rope parameters with observational data from
GONG, SDO/HMI, SOHO/LASCO, and STEREO/COR. We automate this process
so that minimum manual intervention is required in specifying the CME
initial state. With the newly developed data-driven Eruptive Event
Generator Gibson-Low (EEGGL), we present a method to derive Gibson-Low
(GL) flux rope parameters through a handful of observational quantities
so that the modeled CMEs can propagate with the desired CME speeds near
the Sun. A test result with CMEs launched with different Carrington
rotation magnetograms are shown. Our study shows a promising result
for using the first-principles-based MHD global model as a forecasting
tool, which is capable of predicting the CME direction of propagation,
arrival time, and ICME magnetic field at 1 AU.
---------------------------------------------------------
Title: Coronal response to EUV jets modeled with the Alfvén Wave
Solar Model
Authors: Szente, Judith; Toth, Gabor; Manchester, Ward B., IV; van der
Holst, Bartholomeus; Landi, Enrico; Gombosi, Tamas; DeVore, Carl R.;
Antiochos, Spiro K.
2016usc..confE..72S Altcode:
We study the thermodynamics of jet phenomena with the use of multiple
wavelength SDO-AIA observations [e.g. Adams (2014) and Moore (2015)]
combined with advanced numerical simulations made with AWSoM coronal
model [van der Holst (2014)]. AWSoM provides a fully three-dimensional,
magnetohydrodynamic description of the solar atmosphere heated by the
dissipation of kinetic Alfvén waves in a self-consistent manner. In
addition, the model's multi-species thermodynamics with electron
heat conduction provides for the accurate construction of synthetic
line-of-sight images of phenomena. We implement our jets in the solar
wind with a magnetic dipole twisted about axis, resulting in EUV jets
similar in topology and dynamics as being observed. We show that the
coronal atmosphere responds at a large-scale as torsional Alfvén waves
propagate into the outer corona (up to 24 solar radii and 40 degrees in
latitude), introduced by the small-scale eruptive reconnection events
at the footpoint of the jet.
---------------------------------------------------------
Title: Threaded-Field-Lines Model for the Low Solar Corona Powered
by the Alfven Wave Turbulence
Authors: Sokolov, Igor V.; van der Holst, Bart; Manchester, Ward B.;
Ozturk, Doga Can Su; Szente, Judit; Taktakishvili, Aleksandre; Tóth,
Gabor; Jin, Meng; Gombosi, Tamas I.
2016arXiv160904379S Altcode:
We present an updated global model of the solar corona, including
the transition region. We simulate the realistic tree-dimensional
(3D) magnetic field using the data from the photospheric magnetic
field measurements and assume the magnetohydrodynamic (MHD) Alfvén
wave turbulence and its non-linear dissipation to be the only source
for heating the coronal plasma and driving the solar wind. In closed
field regions the dissipation efficiency in a balanced turbulence
is enhanced. In the coronal holes we account for a reflection of
the outward propagating waves, which is accompanied by generation of
weaker counter-propagating waves. The non-linear cascade rate degrades
in strongly imbalanced turbulence, thus resulting in colder coronal
holes. The distinctive feature of the presented model is the description
of the low corona as almost-steady-state low-beta plasma motion and
heat flux transfer along the magnetic field lines. We trace the magnetic
field lines through each grid point of the lower boundary of the global
corona model, chosen at some heliocentric distance, $R=R_{b}\sim1.1\
R_\odot$ well above the transition region. One can readily solve the
plasma parameters along the magnetic field line from 1D equations for
the plasma motion and heat transport together with the Alfvén wave
propagation, which adequately describe physics within the heliocentric
distances range, $R_{\odot}<R<R_{b}$, in the low solar corona. By
interfacing this threaded-field-lines model with the full MHD global
corona model at $r=R_{b}$, we find the global solution and achieve a
faster-than-real-time performance of the model on $\sim200$ cores.
---------------------------------------------------------
Title: 3-D Flux Rope Modeling of CME-like Plasma Dynamics in the
PBEX HelCat Experiment
Authors: Fisher, Dustin Mark; Zhang, Y.; Wallace, B.; Gilmore, M.;
Manchester, W.; Arge, C. N.
2016shin.confE..51F Altcode:
The Plasma Bubble Expansion Experiment (PBEX) [1] at UNM uses a
plasma gun to launch jet and spheromak magnetic configurations into
the Helicon-Cathode (HelCat) [2] basic plasma device. The short
scale lengths and dense, collisional nature of the plasma allow
for a parameter regime and dynamics that greatly match those found
in the lower density plasma of the solar wind. This provides unique
experimental access to studying possible CME propagation into the solar
wind. Moreover, the numerous diagnostic capabilities of HelCat allow
for validation of numerical codes that aim to make predictive models
of real-time solar events. <P />Preliminary modeling and analysis
of the PBEX experiment is presented using the highly-developed 3-D,
MHD, BATS-R-US [3,4] solar coronal model of the Space Weather Modeling
Framework (SWMF) [3,5] code from the University of Michigan. BATS-R-US
employs an adaptive mesh refinement (AMR) grid that enables the
capture and resolution of shock structures and current sheets which
can subsequently be compared to high-resolution magnetogram data. Such
modeling may provide insights into the role of heating and reconnection
in CME-like events. <P />Initial modeling uses the Titov-Demoulin
(TD)[6] flux rope model to mimic plasma bubbles launched from the
PBEX gun. A spheromak-based flux model may also be used in the ongoing
modeling.
---------------------------------------------------------
Title: Achieving Forecasts in the Thermosphere and Ionosphere with
Lead Times of a Few Days
Authors: Mannucci, A. J.; Meng, X.; Verkhoglyadova, O. P.; Tsurutani,
B.; Manchester, W.; Sharma, S.
2015AGUFMSH11A2374M Altcode:
Forecasting space weather requires the development of
first-principles-based models for the coupled Sun-Earth System. To
achieve lead times of a few days for disturbances in planetary
thermospheres and ionospheres, models of the solar wind propagating
through the heliosphere are required. An active research community
has achieved a suite of models that describe conditions within, and
coupling between, the solar wind, the Earth's magnetosphere and the
ionosphere. At least one version of each model in the suite is available
for broad community use and investigation. While these models represent
an important step towards the goal of achieving accurate space weather
forecasts, it is recognized that certain physical processes are not
represented in these models, with unknown impact on the forecasts. We
suggest an approach towards improved space weather forecasts that
emphasizes model evaluation techniques, providing detailed information
on how the physical processes represented in the models affect forecasts
based on those models. Such detailed information permits the models to
be used for investigating science questions, and permits observations
to be the basis for improving the models and increasing scientific
understanding. In this talk, we present upper atmosphere forecasting
results using community models of the coupled Sun-Earth system. We
describe our approach to analyzing the physics of ionospheric storms
as represented in the Global Ionosphere Thermosphere Model developed at
the University of Michigan. Such analysis involves both an approach to
model diagnostics and the use of a comprehensive set of observations. We
compare forecast results for high-speed solar wind stream storms and
storms initiated by solar coronal mass ejections. First-principle
and empirically based approaches to coupling between the solar wind
and ionosphere are compared. These comparisons provide insight into
the strengths and limitations, and areas for future improvement, of
first-principles models as they are used to forecast the Sun-Earth
interaction.
---------------------------------------------------------
Title: Modeling AWSoM CMEs with EEGGL: A New Approach for Space
Weather Forecasting
Authors: Jin, M.; Manchester, W.; van der Holst, B.; Sokolov, I.;
Toth, G.; Vourlidas, A.; de Koning, C. A.; Gombosi, T. I.
2015AGUFMSH43C..02J Altcode:
The major source of destructive space weather is coronal mass ejections
(CMEs). However, our understanding of CMEs and their propagation in the
heliosphere is limited by the insufficient observations. Therefore,
the development of first-principals numerical models plays a vital
role in both theoretical investigation and providing space weather
forecasts. Here, we present results of the simulation of CME propagation
from the Sun to 1AU by combining the analytical Gibson & Low (GL)
flux rope model with the state-of-art solar wind model AWSoM. We also
provide an approach for transferring this research model to a space
weather forecasting tool by demonstrating how the free parameters of
the GL flux rope can be prescribed based on remote observations via
the new Eruptive Event Generator by Gibson-Low (EEGGL) toolkit. This
capability allows us to predict the long-term evolution of the CME
in interplanetary space. We perform proof-of-concept case studies to
show the capability of the model to capture physical processes that
determine CME evolution while also reproducing many observed features
both in the corona and at 1 AU. We discuss the potential and limitations
of this model as a future space weather forecasting tool.
---------------------------------------------------------
Title: Simulation of Active-Region-Scale Flux Emergence
Authors: Manchester, W.; van der Holst, B.
2015AGUFMSH13A2433M Altcode:
Shear flows long observed in solar active regions are now understood
to be a consequence of the Lorentz force that develops from a complex
interaction between magnetic fields and the thermal pressure of the
Sun's gravitationally stratified atmosphere. The shearing motions
transport magnetic flux and energy from the submerged portion of
the field to the corona providing the necessary energy for flares,
filament eruptions and CMEs. To further examine this shearing process,
we simulate flux emergence on the scale of active regions with a
large-scale model of the near surface convection zone constructed on
an adaptive spherical grid. This model is designed to simulate flux
emerging on the scale of active regions from a depth of 30 Mm. Here,
we show results of a twisted flux rope emerging through the hierarchy
of granular convection, and examine the flow patterns that arise as
the flux approaches the photosphere. We show how these organized flows
driven by the Lorentz force cause the coronal field evolve to a highly
non-potential configuration capable of driving solar eruptions such
as CMEs and flares.
---------------------------------------------------------
Title: The Physics of CME Propagation
Authors: Manchester, W.
2015AGUFMSH42A..03M Altcode:
Coronal mass ejections (CMEs) have been the subject of intense
investigation since their discovery more than forty years ago, which
have produced enormous advances in our understanding of the structure
and dynamics of CMEs. Here, we examine the results of numerical
simulations to identify a wide range of physical processes that govern
the interaction of CMEs with the corona and the larger heliosphere. We
focus on processes which determine the bulk transport of plasma
and magnetic flux including kinematic effects, magnetohydrodynamic
instabilities and magnetic reconnection. We compare simulation
results to remote-sensing observations and in-situ measurements to
both verify the models and explain a number of observed properties of
interplanetary CMEs.
---------------------------------------------------------
Title: Dynamics of Polar Jets from the Chromosphere to the Corona:
Mass, Momentum and Energy Transfer
Authors: Szente, J.; Toth, G.; Manchester, W.; van der Holst, B.;
Landi, E.; DeVore, C. R.; Gombosi, T. I.
2015AGUFMSH23D..05S Altcode:
Coronal jets, routinely observed by multiple instruments at
multiple wavelengths, provide a unique opportunity to understand
the relationships between magnetic field topology, reconnection, and
solar wind heating and acceleration. We simulate coronal jets with the
Alfvén Wave Solar Model (AWSoM) [van der Holst (2014)] and focus our
study on the thermodynamical evolution of the plasma. AWSoM solves
the two-temperature MHD equations with electron heat conduction,
which not only addresses the thermodynamics of individual species,
but also allows for the construction of synthetic images from the EUV
and soft X-ray wavelength range. Our jet model takes the form of a
slowly rotating bipole field imbedded in the open magnetic field of
a coronal hole; a topology suggested by observations. We follow the
formation and evolution of polar jets starting from the chromosphere
and extending into the outer corona. The simulations show small-scale
eruptive reconnection events that self-consistently heat and accelerate
the solar wind. Our results provide a quantitative comparison to
observations made in the EUV and X-ray spectrum.
---------------------------------------------------------
Title: New Publicly Available EEGGL Tool for Simulating Coronal
Mass Ejections.
Authors: Sokolov, I.; Manchester, W.; van der Holst, B.; Gombosi,
T. I.; Jin, M.; Mullinix, R.; Taktakishvili, A.; Chulaki, A.; Toth, G.
2015AGUFMSH21B2403S Altcode:
We present and demonstrate a new tool, EEGGL (Eruptive Event Generator
using Gibson-Low configuration) for simulating CMEs (Coronal Mass
Ejections). CMEs are among the most significant space weather events,
producing the radiation hazards (via the diffuse shock acceleration
of the Solar Energetic Particles - SEPs), the interplanetary shock
waves as well as the geomagnetic activity due to the drastic changes of
the interplanetary magnetic field within the "magnetic clouds" ("flux
ropes"). Some of this effects may be efficiently simulated using the
"cone model", which is employed in the real-time simulations of the
ongoing CMEs at the NASA-Goddard Space Flight Center. The cone model
provides a capability to predict the location, time, width and shape of
the hydrodynamic perturbation in the upper solar corona (at ~0.1 AU),
which can be used to drive the heliospheric simulation (with the ENLIL
code, for example). At the same time the magnetic field orientation
in this perturbation is uncertain within the cone model, which limits
the capability of the geomagnetic activity forecast. The new EEGGL
tool http://ccmc.gsfc.nasa.gov/analysis/EEGGL/recently developed at
the Goddard Space Flight Center in collaboration with the University
of Michigan provides a new capability for both evaluating the magnetic
field configuration resulting from the CME and tracing the CME through
the solar corona. In this way not only the capability to simulate the
magnetic field evolution at 1 AU may be achieved, but also the more
extensive comparison with the CME observations in the solar corona may
be achieved. Based on the magnetogram and evaluation of the CME initial
location and speed, the user may choose the active region from which
the CME originates and then the EEGGL tools provides the parameters
of the Gibson-Low magnetic configuration to parameterize the CME. The
recommended parameters may be used then to drive the simulation of CME
propagation from the low solar corona to 1 AU using the global code
for simulating the solar corona and inner heliosphere. The Community
Coordinated Modeling Center (CCMC) provides the capability for CME
runs-on-request, to the heliophysics community.
---------------------------------------------------------
Title: Heliospheric Propagation of Coronal Mass Ejections: A Review
Authors: Lugaz, Noé; Farrugia, Charles; Schwadron, Nathan; Manchester,
Ward B.
2015IAUGA..2237318L Altcode:
Coronal mass ejections (CMEs) are the most energetic events from the
Sun and the major driver of intense geomagnetic activity. Traditionally,
most research has focused on understanding the causes of CME initiation
and the specificities of the interaction between CMEs and Earth's
magnetosphere. In-between these two domains, CMEs propagate in the
heliosphere, interacting with the solar wind and other transient and
corotating structures. The heliospheric propagation of CMEs can now
be directly imaged remotely, making it possible to directly compare
solar and coronal properties with CME properties measured in situ
near Earth. In addition, numerical simulations can be used to get a
more complete, 3-D view of CMEs. Here, I will review progress made
in the past decade in our understanding of CME propagation and how
it affects the CME properties as measured near Earth. In particular,
I will discuss CME radial expansion, CME deflection and rotation as
well as the interaction of successive CMEs and the interaction of a
CME with corotating solar wind structures.
---------------------------------------------------------
Title: A Steady-state Picture of Solar Wind Acceleration and Charge
State Composition Derived from a Global Wave-driven MHD Model
Authors: Oran, R.; Landi, E.; van der Holst, B.; Lepri, S. T.;
Vásquez, A. M.; Nuevo, F. A.; Frazin, R.; Manchester, W.; Sokolov,
I.; Gombosi, T. I.
2015ApJ...806...55O Altcode: 2014arXiv1412.8288O
The higher charge states found in slow (<400 km s<SUP>-1</SUP>)
solar wind streams compared to fast streams have supported the
hypothesis that the slow wind originates in closed coronal loops
and is released intermittently through reconnection. Here we examine
whether a highly ionized slow wind can also form along steady and open
magnetic field lines. We model the steady-state solar atmosphere using
the Alfvén Wave Solar Model (AWSoM), a global MHD model driven by
Alfvén waves, and apply an ionization code to calculate the charge
state evolution along modeled open field lines. This constitutes the
first charge state calculation covering all latitudes in a realistic
magnetic field. The ratios {{O}<SUP>+7</SUP>}/{{O}<SUP>+6</SUP>}
and {{C}<SUP>+6</SUP>}/{{C}<SUP>+5</SUP>} are compared to in situ
Ulysses observations and are found to be higher in the slow wind, as
observed; however, they are underpredicted in both wind types. The
modeled ion fractions of S, Si, and Fe are used to calculate
line-of-sight intensities, which are compared to Extreme-ultraviolet
Imaging Spectrometer (EIS) observations above a coronal hole. The
agreement is partial and suggests that all ionization rates are
underpredicted. Assuming the presence of suprathermal electrons improved
the agreement with both EIS and Ulysses observations; importantly,
the trend of higher ionization in the slow wind was maintained. The
results suggest that there can be a sub-class of slow wind that is
steady and highly ionized. Further analysis shows that it originates
from coronal hole boundaries (CHBs), where the modeled electron
density and temperature are higher than inside the hole, leading to
faster ionization. This property of CHBs is global and observationally
supported by EUV tomography.
---------------------------------------------------------
Title: Forecasting ionospheric space weather with applications to
satellite drag and radio wave communications and scintillation
Authors: Mannucci, Anthony J.; Tsurutani, Bruce T.; Verkhoglyadova,
Olga P.; Meng, Xing; Pi, Xiaoqing; Kuang, Da; Wang, Chunming; Rosen,
Gary; Ridley, Aaron; Lynch, Erin; Sharma, Surja; Manchester, Ward B.;
van der Holst, Bart
2015TESS....111202M Altcode:
The development of quantitative models that describe physical
processes from the solar corona to the Earth’s upper atmosphere
opens the possibility of numerical space weather prediction with a
lead-time of a few days. Forecasting solar wind-driven variability
in the ionosphere and thermosphere poses especially stringent
tests of our scientific understanding and modeling capabilities, in
particular of coupling processes to regions above and below. We will
describe our work with community models to develop upper atmosphere
forecasts starting with the solar wind driver. A number of phenomena
are relevant, including high latitude energy deposition, its impact
on global thermospheric circulation patterns and composition, and
global electrodynamics. Improved scientific understanding of this
sun to Earth interaction ultimately leads to practical benefits. We
will focus on two ways the upper atmosphere affects life on Earth:
by changing satellite orbits, and by interfering with long-range
radio communications. Challenges in forecasting these impacts will be
addressed, with a particular emphasis on the physical bases for the
impacts, and how they connect upstream to the sun and the heliosphere.
---------------------------------------------------------
Title: Counter-streaming alpha proton plasmas in an eroding magnetic
cloud: new insights into space plasma evolution from Wind
Authors: Szente, J.; Toth, G.; Manchester, W.; van der Holst, B.;
Landi, E.; DeVore, C. R.; Gombosi, T. I.
2014AGUFMSH23D..05S Altcode:
Coronal jets, routinely observed by multiple instruments at
multiple wavelengths, provide a unique opportunity to understand
the relationships between magnetic field topology, reconnection, and
solar wind heating and acceleration. We simulate coronal jets with the
Alfvén Wave Solar Model (AWSoM) [van der Holst (2014)] and focus our
study on the thermodynamical evolution of the plasma. AWSoM solves
the two-temperature MHD equations with electron heat conduction,
which not only addresses the thermodynamics of individual species,
but also allows for the construction of synthetic images from the EUV
and soft X-ray wavelength range. Our jet model takes the form of a
slowly rotating bipole field imbedded in the open magnetic field of
a coronal hole; a topology suggested by observations. We follow the
formation and evolution of polar jets starting from the chromosphere
and extending into the outer corona. The simulations show small-scale
eruptive reconnection events that self-consistently heat and accelerate
the solar wind. Our results provide a quantitative comparison to
observations made in the EUV and X-ray spectrum.
---------------------------------------------------------
Title: Coronal Hole Boundaries as Source Regions of a Steady
Slow Solar Wind: Global Modeling of Charge State Composition and
Sun-to-Earth Observations
Authors: Oran, R.; Landi, E.; van der Holst, B.; Lepri, S. T.;
Manchester, W.; Frazin, R. A.; Nuevo, F.; Vásquez, A. M.; Sokolov,
I.; Gombosi, T. I.
2014AGUFMSH33A4122O Altcode:
We combine the results from a global MHD model of the solar atmosphere
with a charge state evolution code in order to predict the large-scale
variation of charge state composition in the fast and slow solar wind
during solar minimum. The model captures the well-known increase in
charge state ratios C+6/ C+5 and O+7/O+6 in the slow wind, inline with
Ulysses observations. We present a theoretical picture explaining
the formation of these increases, which are related to regions of
higher electron density and temperature near the boundaries of coronal
holes. We verify the existence of these regions using a 3D tomographic
reconstruction of the lower corona. This work establishes that a steady
slow wind flowing along open magnetic field lines can carry high charge
states without invoking reconnection with closed field regions. This
subset of slow wind can play a role explaining the properties of the
non-steady slow wind, and complement dynamic models of slow solar
wind formation.
---------------------------------------------------------
Title: Ensemble Space Weather Forecasting with the SWMF
Authors: Frazin, R. A.; van der Holst, B.; Manchester, W.; Sokolov,
I.; Huang, Z.; Gombosi, T. I.
2014AGUFMSH53A4207F Altcode:
An accurate, physics-based model of the heliosphere that extends
from the Sun to the Earth and beyond is the “holy grail” of space
weather forecasting. Global models that start in the corona (or below)
are driven by representations of the full-Sun photospheric magnetic
field. Traditionally, the full-Sun magnetic field has been provided
by synoptic magnetograms, which are created over a 28 day period
and are not an accurate representation of the magnetic field at any
given time. Recently, several groups have been producing so-called
“synchronic maps,” which fuse magnetograms and models including
differential rotation, meridional transport and diffusion to create
time-dependent full-Sun magnetic field maps. Here, we include a variety
of synchronic and synoptic maps to create an ensemble space weather
model and report on the results.
---------------------------------------------------------
Title: Simulating CME Eruptions from Active Regions
Authors: Manchester, W.; van der Holst, B.
2014AGUFMSH51E..03M Altcode:
Fast coronal mass ejections (CMEs) typically erupt from the filament
channels of active regions where the magnetic field is in a highly
non potential state. In this talk, we discuss two numerical models
under development that will simulate the evolution of active regions
and the buildup of magnetic energy that leads to filament eruptions
and CMEs. The first model, the so called regional model simulates
the area of an active region in a domain that extends from just
above the photosphere at its base to a height of 100 Mm in the low
corona. The physics of this model is extended magnetohydrodynamics
(MHD), which includes such physical processes as field aligned heat
conduction, radiative losses, and tabular equation of state that
allow for a self-consistent treatment of the atmosphere including
the transition region. For this model, boundary conditions for the
magnetic field fields are specified directly from HMI vector magnetogram
observations. The second model addresses the buoyant rise of magnetic
flux from the convection zone through the photosphere to allow for the
self consistent formation and evolution of active regions that leads
to the buildup of magnetic free energy. We compare results from this
second model to SDO/HMI observations of the 7 January 2014 events to
show that the simulation has captured the basic physics of magnetic
field evolution an energy build up necessary for large-scale eruptions.
---------------------------------------------------------
Title: Global MHD Simulation of the Coronal Mass Ejection on 2011
March 7: from Chromosphere to 1 AU
Authors: Jin, M.; Manchester, W.; van der Holst, B.; Sokolov, I.;
Toth, G.; Vourlidas, A.; de Koning, C. A.; Gombosi, T. I.
2014AGUFMSH43A4176J Altcode:
Performing realistic simulations of solar eruptions and validating
those simulations with observations are important goals in order
to achieve accurate space weather forecasts. Here, we perform and
analyze results of a global magnetohydrodyanmic (MHD) simulation of the
fast coronal mass ejection (CME) that occurred on 2011 March 7. The
simulation is made using the newly developed Alfven Wave Solar Model
(AWSoM), which describes the background solar wind starting from the
upper chromosphere and expands to 24 Rs. Coupling of AWSoM to an inner
heliosphere (IH) model with the Space Weather Modeling Framework (SWMF)
extends the total domain beyond the orbit of Earth. Physical processes
included in the model are multi-species thermodynamics, electron heat
conduction (both collisional and collisionless formulations), optically
thin radiative cooling, and Alfven-wave pressure that accelerates
the solar wind. The Alfven-wave description is physically consistent,
including non-WKB reflection and physics-based apportioning of turbulent
dissipative heating to both electrons and protons. Within this model,
we initiate the CME by using the Gibson-Low (GL) analytical flux rope
model and follow its evolution for days, in which time it propagates
beyond 1 AU. A comprehensive validation study is performed using
remote as well as in-situ observations from SDO, SOHO, STEREOA/B,
and OMNI. Our results show that the new model can reproduce many
of the observed features near the Sun (e.g., CME-driven EUV waves,
deflection of the flux rope from the coronal hole, "double-front"
in the white light images) and in the heliosphere (e.g., CME-CIR
interaction, shock properties at 1 AU). The CME-driven shock arrival
time is within 1 hour of the observed arrival time, and nearly all the
in-situ parameters are correctly simulated, which suggests the global
MHD model as a powerful tool for the space weather forecasting.
---------------------------------------------------------
Title: Magnetic Flux Erosion and Redistribution during CME Propagation
Authors: Lavraud, B.; Ruffenach, A.; Manchester, W.; Farrugia, C. J.;
Demoulin, P.; Dasso, S.; Sauvaud, J. A.; Rouillard, A. P.; Foullon,
C.; Owens, M. J.; Savani, N.; Kajdic, P.; Luhmann, J. G.; Galvin, A. B.
2014AGUFMSH22A..01L Altcode:
We will review recent works which highlight the occurrence of magnetic
flux erosion and redistribution at the front of coronal mass ejections
(when they have the structure of a well-defined magnetic cloud). Two
main processes have been found and will be presented. The first comes
from the occurrence of magnetic reconnection between the magnetic
cloud and its sheath ahead, leading to magnetic flux erosion and
redistribution, with associated large scale topological changes. The
second may occur when dense filament material in the coronal mass
ejection pushes its way through the structure and comes in direct
contact with the shocked plasma in the sheath ahead. This leads to
diverging non-radial flows in front of the CME which transport poloidal
flux of the flux rope to the sides of the magnetic cloud.
---------------------------------------------------------
Title: Predicting ICME Magnetic Fields with a Numerical Flux Rope
Model
Authors: Manchester, W.; van der Holst, B.; Sokolov, I.
2014AGUFMSH21C4137M Altcode:
Coronal mass ejections (CMEs) are a dramatic manifestation of solar
activity that release vast amounts of plasma into the heliosphere,
and have many effects on the interplanetary medium and on planetary
atmospheres, and are the major driver of space weather. CMEs occur with
the formation and expulsion of large-scale flux ropes from the solar
corona, which are routinely observed in interplanetary space. Simulating
and predicting the structure and dynamics of these ICME magnetic fields
is essential to the progress of heliospheric science and space weather
prediction. We combine observations made by different observing
techniques of CME events to develop a numerical model capable of
predicting the magnetic field of interplanetary coronal mass ejections
(ICMES). Photospheric magnetic field measurements from SOHO/MDI and
SDO/HMI are used to specify a coronal magnetic flux rope that drives
the CMEs. We examine halo CMEs events that produced clearly observed
magnetic clouds at Earth and present our model predictions of these
events with an emphasis placed on the z component of the magnetic
field. Comparison of the MHD model predictions with coronagraph
observations and in-situ data allow us to robustly determine the
parameters that define the initial state of the driving flux rope,
thus providing a predictive model.
---------------------------------------------------------
Title: Forecasting Ionospheric Space Weather Due To High Speed Streams
Authors: Mannucci, A. J.; Verkhoglyadova, O. P.; Meng, X.; Tsurutani,
B. T.; Pi, X.; Lynch, E. M.; Sharma, S.; Ridley, A. J.; Manchester,
W.; Wang, C.; Rosen, G.
2014AGUFMSA12A..08M Altcode:
The development of quantitative models that describe physical processes
from the Solar corona to the Earth's upper atmosphere opens the
possibility of numerical space weather forecasting with a lead time of
a few days. We will describe our work with community models to develop
ionospheric forecasts starting with the solar wind driver. Our current
focus is the daytime ionospheric response to high-speed solar wind
streams that are prevalent during the declining phase of the solar
cycle. A number of challenges are addressed, including high latitude
energy deposition and its impact on global thermospheric circulation
patterns and composition. The degree to which forecasts are successful
depends on the manner in which Alfvenic solar wind variability drives
the ionospheric response. Large-scale and small-scale magnetospheric
processes are important to consider, including the role of particle
precipitation in depositing energy into the thermosphere and in changing
ionospheric conductivities through increased ionization. Accurate
forecasts require that we address the following question: what are the
impacts of (less predictable) small-scale processes in determining the
large-scale daytime ionospheric response, versus the role of larger
scale magnetospheric processes that may be easier to predict? We
will compare model-based forecasts with a variety of satellite and
ground-based data sources to assess the fidelity of physical processes
represented in the models. Outstanding science questions that are
relevant to forecasts are described.
---------------------------------------------------------
Title: Simulation of magnetic cloud erosion during propagation
Authors: Manchester, W. B.; Kozyra, J. U.; Lepri, S. T.; Lavraud, B.
2014JGRA..119.5449M Altcode:
We examine a three-dimensional (3-D) numerical magnetohydrodynamic (MHD)
simulation describing a very fast interplanetary coronal mass ejection
(ICME) propagating from the solar corona to 1 AU. In conjunction
with its high speed, the ICME evolves in ways that give it a unique
appearance at 1 AU that does not resemble a typical ICME. First,
as the ICME decelerates far from the Sun in the solar wind, filament
material at the back of the flux rope pushes its way forward through the
flux rope. Second, diverging nonradial flows in front of the filament
transport poloidal flux of the rope to the sides of the ICME. Third,
the magnetic flux rope reconnects with the interplanetary magnetic
field (IMF). As a consequence of these processes, the flux rope
partially unravels and appears to evolve to an entirely unbalanced
configuration. At the same time, filament material at the base of the
flux rope moves forward and comes in direct contact with the shocked
plasma in the CME sheath. We find evidence that such remarkable behavior
has actually occurred when we examine a very fast CME that erupted
from the Sun on 2005 January 20. In situ observations of this event
near 1 AU show very dense cold material impacting the Earth following
immediately behind the CME sheath. Charge state analysis shows this
dense plasma is filament material. Consistent with the simulation, we
find the poloidal flux (B<SUB>z</SUB>) to be entirely unbalanced, giving
the appearance that the flux rope has eroded. The dense solar filament
material and unbalanced positive IMF B<SUB>z</SUB> produced a number
of anomalous features in a moderate magnetic storm already underway,
which are described in a companion paper by Kozyra et al. (2014).
---------------------------------------------------------
Title: Solar filament impact on 21 January 2005: Geospace consequences
Authors: Kozyra, J. U.; Liemohn, M. W.; Cattell, C.; De Zeeuw, D.;
Escoubet, C. P.; Evans, D. S.; Fang, X.; Fok, M. -C.; Frey, H. U.;
Gonzalez, W. D.; Hairston, M.; Heelis, R.; Lu, G.; Manchester, W. B.;
Mende, S.; Paxton, L. J.; Rastaetter, L.; Ridley, A.; Sandanger,
M.; Soraas, F.; Sotirelis, T.; Thomsen, M. W.; Tsurutani, B. T.;
Verkhoglyadova, O.
2014JGRA..119.5401K Altcode:
On 21 January 2005, a moderate magnetic storm produced a number of
anomalous features, some seen more typically during superstorms. The
aim of this study is to establish the differences in the space
environment from what we expect (and normally observe) for a
storm of this intensity, which make it behave in some ways like a
superstorm. The storm was driven by one of the fastest interplanetary
coronal mass ejections in solar cycle 23, containing a piece of the
dense erupting solar filament material. The momentum of the massive
solar filament caused it to push its way through the flux rope as
the interplanetary coronal mass ejection decelerated moving toward
1 AU creating the appearance of an eroded flux rope (see companion
paper by Manchester et al. (2014)) and, in this case, limiting the
intensity of the resulting geomagnetic storm. On impact, the solar
filament further disrupted the partial ring current shielding in
existence at the time, creating a brief superfountain in the equatorial
ionosphere—an unusual occurrence for a moderate storm. Within 1
h after impact, a cold dense plasma sheet (CDPS) formed out of the
filament material. As the interplanetary magnetic field (IMF) rotated
from obliquely to more purely northward, the magnetotail transformed
from an open to a closed configuration and the CDPS evolved from
warmer to cooler temperatures. Plasma sheet densities reached tens
per cubic centimeter along the flanks—high enough to inflate the
magnetotail in the simulation under northward IMF conditions despite
the cool temperatures. Observational evidence for this stretching was
provided by a corresponding expansion and intensification of both the
auroral oval and ring current precipitation zones linked to magnetotail
stretching by field line curvature scattering. Strong Joule heating in
the cusps, a by-product of the CDPS formation process, contributed to
an equatorward neutral wind surge that reached low latitudes within 1-2
h and intensified the equatorial ionization anomaly. Understanding the
geospace consequences of extremes in density and pressure is important
because some of the largest and most damaging space weather events
ever observed contained similar intervals of dense solar material.
---------------------------------------------------------
Title: Global Magnetohydrodynamics Simulation of the Coronal Mass
Ejection on 2011 March 7: from Chromosphere to 1 AU
Authors: Jin, Meng; Manchester, W. B.; van der Holst, B.; Sokolov,
I.; Toth, G.; Vourlidas, A.; de Koning, C.; Gombosi, T. I.
2014shin.confE..10J Altcode:
Performing realistic simulations of solar eruptions and validating
those simulations with observations are important goals in order to
achieve accurate space weather forecasts. Here, we analyze results
of a global magnetohydrodyanmic (MHD) simulation of the fast coronal
mass ejection (CME) that occurred on 2011 March 7. The simulation is
made using the newly developed Alfven Wave Solar Model (AWSoM), which
describes the background solar wind starting from the upper chromosphere
and expends to 24 Rs. Coupling of AWSoM to an inner heliosphere (IH)
model with the Space Weather Modeling Framework extends the total domain
beyond the orbit of Earth. Physical processes included in the model are
multi-species thermodynamics, electron heat conduction (both collisional
and collisionless formulation), optically thin radiative cooling and
Alfven-wave pressure that accelerates the solar wind. The Alfven-wave
description is physically self-consistent, including non-WKB reflection
and physics-based apportioning of turbulent dissipative heating to both
electrons and protons. Within this model, we initiate the CME by using
the Gibson-Low (GL) analytical flux rope model and follow its evolution
for days, in which time it propagates beyond 1 AU. A comprehensive
validation study is performed using remote as well as the in situ
observations from SDO, SOHO, STEREOA/B, and OMNI. Our results show
that the new model can reproduce many of the observed features near
the Sun (e.g., CME-driven EUV waves, deflection of the flux rope from
the coronal hole, double-front in the white light images) and in the
heliosphere (e.g., CME-CIR interaction, shock properties at 1 AU). By
fitting the CME speeds near the Sun with observations, the CME-driven
shock arrival time is within 1 hour of the observed arrival time and
all the in situ parameters are correctly simulated, which suggests the
global MHD model as a powerful tool for the space weather forecasting.
---------------------------------------------------------
Title: Charge State Evolution in the Fast and Slow Wind Predicted
by a Global Wave-Driven Solar Model
Authors: Oran, Rona; Landi, Enrico; van der Holst, Bart; Lepri, Susan;
Vásquez, Alberto; Nuevo, Federico; Frazin, Richard; Manchester,
Ward; Sokolov, Igor; Gombosi, Tamas
2014shin.confE..66O Altcode:
The mechanisms responsible for the formation of the slow solar wind are
a subject of vigorous debate in the heliospheric community. The heavy
ion charge state composition measured in-situ at 1AU and beyond depend
on the plasma conditions along the wind trajectory close to the Sun,
and are known to be significantly different when measured in either
the fast or slow solar wind. As such, heavy ion charge states have
played an important role in testing the various theories concerning
the formation of the fast and slow wind, and in determining the source
region of the slow solar wind. <P />We will present results from a
global MHD model of the solar atmosphere, in which the wind is heated
and accelerated by Alfven waves. The global model results are used to
drive a charge state evolution code along open magnetic field lines at
all heliographic latitudes. The resulting charge state distributions of
several ions are compared to in-situ Ulysses measurements at 1-2AU as
well as to high resolution spectra observed in the lower corona. We
find that the large scale latitudinal variation in charge states
is captured by the model. In particular, the model can reproduce
and explain the increase in the O+7/O+6, C+6/C+5 ratios in the slow
(steady) solar wind compared to the fast wind. We demonstrate that these
increases are associated with a higher plasma density at the base of
open field lines whose foot-points are located near the boundary of
the coronal holes. We show that this density enhancement as predicted
by the model is consistent with EUV tomographic reconstructions of the
lower corona. We discuss the possible interpretations and implications
of our results to our understanding of solar wind formation.
---------------------------------------------------------
Title: Alfvén Wave Solar Model (AWSoM): Coronal Heating
Authors: van der Holst, B.; Sokolov, I. V.; Meng, X.; Jin, M.;
Manchester, W. B., IV; Tóth, G.; Gombosi, T. I.
2014ApJ...782...81V Altcode: 2013arXiv1311.4093V
We present a new version of the Alfvén wave solar model, a global model
from the upper chromosphere to the corona and the heliosphere. The
coronal heating and solar wind acceleration are addressed with
low-frequency Alfvén wave turbulence. The injection of Alfvén
wave energy at the inner boundary is such that the Poynting flux is
proportional to the magnetic field strength. The three-dimensional
magnetic field topology is simulated using data from photospheric
magnetic field measurements. This model does not impose open-closed
magnetic field boundaries; those develop self-consistently. The
physics include the following. (1) The model employs three different
temperatures, namely the isotropic electron temperature and the
parallel and perpendicular ion temperatures. The firehose, mirror,
and ion-cyclotron instabilities due to the developing ion temperature
anisotropy are accounted for. (2) The Alfvén waves are partially
reflected by the Alfvén speed gradient and the vorticity along the
field lines. The resulting counter-propagating waves are responsible
for the nonlinear turbulent cascade. The balanced turbulence due to
uncorrelated waves near the apex of the closed field lines and the
resulting elevated temperatures are addressed. (3) To apportion the
wave dissipation to the three temperatures, we employ the results
of the theories of linear wave damping and nonlinear stochastic
heating. (4) We have incorporated the collisional and collisionless
electron heat conduction. We compare the simulated multi-wavelength
extreme ultraviolet images of CR2107 with the observations from
STEREO/EUVI and the Solar Dynamics Observatory/AIA instruments. We
demonstrate that the reflection due to strong magnetic fields in the
proximity of active regions sufficiently intensifies the dissipation
and observable emission.
---------------------------------------------------------
Title: Geo-effectiveness and radial dependence of magnetic cloud
erosion by magnetic reconnection
Authors: Lavraud, Benoit; Ruffenach, Alexis; Rouillard, Alexis P.;
Kajdic, Primoz; Manchester, Ward B.; Lugaz, Noé
2014JGRA..119...26L Altcode:
flux erosion by magnetic reconnection occurs at the front of at least
some magnetic clouds (MCs). We first investigate how erosion influences
the geo-effectiveness of MCs in a general sense and using a south-north
magnetic polarity MC observed on 18-20 October 1995. Although the
magnetic shear at its front may not be known during propagation,
measurements at 1 AU show signatures of local reconnection. Using a
standard MC model, an empirical model of the geomagnetic response (Dst),
and an observational estimate of the magnetic flux erosion, we find that
the strength of the observed ensuing storm was ~30% lower than if no
erosion had occurred. We then discuss the interplay between adiabatic
compression and magnetic erosion at the front of MCs. We conclude that
the most geo-effective configuration for a south-north polarity MC
is to be preceded by a solar wind with southward IMF. This stems not
only from the formation of a geo-effective sheath ahead of it but also
from the adiabatic compression and reduced (or lack thereof) magnetic
erosion which constructively conspire for the structure to be more
geo-effective. Finally, assuming simple semiempirical and theoretical
Alfvén speed profiles expected from expansion to 1 AU, we provide
first-order estimates of the erosion process radial evolution. We
find that the expected reconnection rates during propagation allow for
significant erosion, on the order of those reported. Calculations also
suggest that most of the erosion should occur in the inner heliosphere,
and up to ~50% may yet occur beyond Mercury's orbit.
---------------------------------------------------------
Title: Global ICME-Mars Interaction and Induced Atmospheric Loss
Authors: Fang, X.; Ma, Y.; Manchester, W.
2013AGUFM.P21A1701F Altcode:
Without the shielding of a strong intrinsic magnetic field, the
present-day Mars atmosphere is more vulnerable to external solar
wind forcing than the Earth's atmosphere. Therefore interplanetary
coronal mass ejections (ICMEs) are expected to drive disturbances in
the Mars environment in a profoundly different way, which, however,
is poorly understood due to the lack of coordinated solar wind and
Mars observations. In this study, three sophisticated models work in
concert to simulate the physical domain extending from the solar corona
to near-Mars space for the 13 May 2005 ICME event. The Space Weather
Modeling Framework (SWMF) will be used to investigate the interaction
of the ICME with the ambient solar wind and monitor its propagation
from the Sun to the planet. A 3-D MHD model for Mars will be applied
to assess the planetary atmospheric/ionospheric responses during the
ICME passage of Mars. In the Mars weak magnetic field environment, the
ion kinetic effects are important and will be included through the use
of a 3-D Monte Carlo pickup ion transport model. These physics-based
modeling efforts enable us to provide a global and time series view
of the Mars response to transient solar wind disturbances and induced
atmospheric loss, which is currently not possible due to the limitation
of observations.
---------------------------------------------------------
Title: The Interaction of Two Coronal Mass Ejections: Influence of
Relative Orientation
Authors: Lugaz, N.; Farrugia, C. J.; Manchester, W. B., IV;
Schwadron, N.
2013ApJ...778...20L Altcode: 2013arXiv1309.2210L
We report on a numerical investigation of two coronal mass ejections
(CMEs) that interact as they propagate in the inner heliosphere. We
focus on the effect of the orientation of the CMEs relative to each
other by performing four different simulations with the axis of
the second CME rotated by 90° from one simulation to the next. Each
magnetohydrodynamic simulation is performed in three dimensions with the
Space Weather Modeling Framework in an idealized setting reminiscent of
solar minimum conditions. We extract synthetic satellite measurements
during and after the interaction and compare the different cases. We
also analyze the kinematics of the two CMEs, including the evolution
of their widths and aspect ratios. We find that the first CME contracts
radially as a result of the interaction in all cases, but the amount of
subsequent radial expansion depends on the relative orientation of the
two CMEs. Reconnection between the two ejecta and between the ejecta
and the interplanetary magnetic field determines the type of structure
resulting from the interaction. When a CME with a high inclination
with respect to the ecliptic overtakes one with a low inclination,
it is possible to create a compound event with a smooth rotation in
the magnetic field vector over more than 180°. Due to reconnection,
the second CME only appears as an extended "tail," and the event
may be mistaken for a glancing encounter with an isolated CME. This
configuration differs significantly from the one usually studied of
a multiple-magnetic-cloud event, which we found to be associated with
the interaction of two CMEs with the same orientation.
---------------------------------------------------------
Title: Earth's collision with a solar filament on 21 January 2005:
Overview
Authors: Kozyra, J. U.; Manchester, W. B.; Escoubet, C. P.; Lepri,
S. T.; Liemohn, M. W.; Gonzalez, W. D.; Thomsen, M. W.; Tsurutani,
B. T.
2013JGRA..118.5967K Altcode:
21 January 2005, one of the fastest interplanetary coronal mass
ejections (ICME) of solar cycle 23, containing exceptionally dense
plasma directly behind the sheath, hit the magnetosphere. We show from
charge-state analysis that this material was a piece of the erupting
solar filament and further, based on comparisons to the simulation
of a fast CME, that the unusual location of the filament material
was a consequence of three processes. As the ICME decelerated, the
momentum of the dense filament material caused it to push through the
flux rope toward the nose. Diverging nonradial flows in front of the
filament moved magnetic flux to the sides of the ICME. At the same
time, reconnection between the leading edge of the ICME and the sheath
magnetic fields worked to peel away the outer layers of the flux rope
creating a remnant flux rope and a trailing region of newly opened
magnetic field lines. These processes combined to move the filament
material into direct contact with the ICME sheath region. Within 1 h
after impact and under northward interplanetary magnetic field (IMF)
conditions, a cold dense plasma sheet formed within the magnetosphere
from the filament material. Dense plasma sheet material continued to
move through the magnetosphere for more than 6 h as the filament passed
by the Earth. Densities were high enough to produce strong diamagnetic
stretching of the magnetotail despite the northward IMF conditions and
low levels of magnetic activity. The disruptions from the filament
collision are linked to an array of unusual features throughout
the magnetosphere, ionosphere, and atmosphere. These results raise
questions about whether rare collisions with solar filaments may, under
the right conditions, be a factor in producing even more extreme events.
---------------------------------------------------------
Title: Evolution of the Global Temperature Structure of the Solar
Corona during the Minimum between Solar Cycles 23 and 24
Authors: Nuevo, Federico A.; Huang, Zhenguang; Frazin, Richard;
Manchester, Ward B., iv; Jin, Meng; Vásquez, Alberto M.
2013ApJ...773....9N Altcode:
The combination of differential emission measure tomography with
extrapolation of the photospheric magnetic field allows determination
of the electron density and electron temperature along individual
magnetic field lines. This is especially useful in quiet-Sun (QS)
plasmas where individual loops cannot otherwise be identified. In Paper
I, this approach was applied to study QS plasmas during Carrington
rotation (CR) 2077 at the minimum between solar cycles (SCs) 23 and
24. In that work, two types of QS coronal loops were identified: "up"
loops in which the temperature increases with height, and "down" loops
in which the temperature decreases with height. While the first ones
were expected, the latter ones were a surprise and, furthermore, were
found to be ubiquitous in the low-latitude corona. In the present work,
we extend the analysis to 11 CRs around the last solar minimum. We
found that the "down" population, always located at low latitudes,
was maximum at the time when the sunspot number was minimum, and the
number of down loops systematically increased during the declining
phase of SC-23 and diminished during the rising phase of SC-24. "Down"
loops are found to have systematically larger values of β than do
"up" loops. These discoveries are interpreted in terms of excitation
of Alfvén waves in the photosphere, and mode conversion and damping
in the low corona.
---------------------------------------------------------
Title: Numerical Simulations of Coronal Mass Ejection on 2011 March 7:
One-temperature and Two-temperature Model Comparison
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Oran, R.;
Sokolov, I.; Toth, G.; Liu, Y.; Sun, X. D.; Gombosi, T. I.
2013ApJ...773...50J Altcode:
During Carrington rotation (CR) 2107, a fast coronal mass ejection (CME;
>2000 km s<SUP>-1</SUP>) occurred in active region NOAA 11164. This
event is also associated with a solar energetic particle event. In
this study, we present simulations of this CME with one-temperature
(1T) and two-temperature (2T: coupled thermodynamics of the electron
and proton populations) models. Both the 1T and 2T models start from
the chromosphere with heat conduction and radiative cooling. The
background solar wind is driven by Alfvén-wave pressure and heated
by Alfvén-wave dissipation in which we have incorporated the balanced
turbulence at the top of the closed field lines. The magnetic field of
the inner boundary is set up using a synoptic map from Solar Dynamics
Observatory/Helioseismic and Magnetic Imager. The Titov-Démoulin
flux-rope model is used to initiate the CME event. We compare the
propagation of fast CMEs and the thermodynamics of CME-driven shocks in
both the 1T and 2T CME simulations. Also, the synthesized white light
images are compared with the Solar and Heliospheric Observatory/Large
Angle and Spectrometric Coronagraph observations. Because there is no
distinction between electron and proton temperatures, heat conduction
in the 1T model creates an unphysical temperature precursor in front
of the CME-driven shock and makes the shock parameters (e.g., shock
Mach number, compression ratio) incorrect. Our results demonstrate
the importance of the electron heat conduction in conjunction with
proton shock heating in order to produce the physically correct CME
structures and CME-driven shocks.
---------------------------------------------------------
Title: Turbulence Model for Multi-Band EUV Emission in the Solar
Atmosphere
Authors: van der Holst, Bart; Sokolov, I.; Manchester, W.; Jin, M.;
Oran, R.; Gombosi, T.
2013shin.confE.104V Altcode:
The low corona is the heart of global solar models, because that is
where the interplanetary magnetic fields, solar wind, coronal heating,
and solar flares originate. Multi-wavelength observations obtained by
SDO/AIA and STEREO/EUVI provide very important detailed information
on the morphology, thermodynamic status and evolution of the low
solar corona. Observations from SDO and STEREO can thus be used to
effectively constrain and validate numerical models of the lower solar
atmosphere. <P />We present a global model of the lower solar corona
in which the coronal heating and solar wind acceleration are addressed
with low-frequency, reflection-driven Alfven wave turbulence. At the
inner boundary the Poynting flux of the Alfven waves is prescribed to
be proportional to the magnetic field strength. A unique key feature
of this model is that the wave dissipation on open and closed field
lines is incorporated in a unified manner. The model does not impose
open-closed magnetic field boundaries, those naturally develop from
the ingested observed photospheric magnetic fields and the used wave
dissipation mechanism. On open field lines the turbulence is strongly
imbalanced, so that the turbulent cascade due to the linear wave
reflection is proportional to the Alfven speed gradients. However,
near the top of closed field the turbulence is balanced, resulting
in enhanced nonlinear dissipation. The simulated multi-wavelength EUV
images are compared with the observations from SDO/AIA and STEREO/EUVI
instruments to test this turbulence model.
---------------------------------------------------------
Title: Global Modeling of the July 23, 2012 Coronal Mass Ejection
and Solar Energetic Particle Event
Authors: Evans, Rebekah Minnel; Kozarev, Kamen A.; Schwadron, Nathan
A.; Opher, Merav; Manchester, Ward; Sokolov, Igor; van der Holst, Bart
2013shin.confE...7E Altcode:
The CME and SEP event of July 23, 2012 was extreme in many ways - the
speed of a CME as imaged in coronagraphs, the speed and magnetic field
strength measured in-situ, and the level of energetic particles. Another
special feature of this event is that it caused SEP events at Earth,
STEREO A and STEREO B, which were very separated at the time. The
extreme and whole-heliosphere nature of this event makes it an
excellent candidate to study with two recently coupled models: the
Space Weather Modeling Framework (SWMF) and the Energetic Particle
Radiation Environment Module (EPREM). The SWMF, which itself couples
three-dimensional magnetohydrodynamic (MHD) models describing the solar
corona and heliosphere, is used to simulate the eruption starting
from the low corona. The MHD output describing the fast CME event
is coupled to a global kinetic simulation of particle acceleration
and transport within EPREM. The output of the particle simulation is
synthetic time-dependent spectra influenced by the dynamics of CME
structures that form self-consistently during propagation. With these
simulations, we can probe how the properties of the CME sheath and shock
vary as the CME interacts with the ambient corona and heliosphere. These
simulations can test current theories of SEP production, including
how SEP properties relate to the properties of the associated CME,
CME-driven shock and coronal environment. Finally, we can trace how
particles that interacted with the CME near the Sun propagate throughout
the heliosphere.
---------------------------------------------------------
Title: CME-CME Interaction: Influence of Relative Orientation
Authors: Lugaz, Noe; Farrugia, C. J.; Manchester, W. B.; Schwadron, N.
2013shin.confE.146L Altcode:
We report on an numerical investigation of the interaction of two
coronal mass ejections (CMEs) as they propagate between the Sun and the
Earth. We focus on the effect of the relative orientation of the CMEs
with respect to each other by performing four different simulations with
the axis of the second CME rotated by 90 degrees from one simulation to
the next. The simulations are performed with the SWMF in an idealized
setting reminiscent of solar minimum conditions. We have extracted
synthetic satellite measurements in the inner heliosphere at 0.15, 0.3,
and 1 AU and have compared the different cases. We find significant
differences in the reconnection between the different ejecta and with
the interplanetary magnetic field (IMF). In particular, when a CME with
a high inclination with respect to the ecliptic overtakes one with a
low inclination, it is possible to create a compound event with smooth
rotations in the magnetic field vector and an extended tail, which may
be mistaken for an usual crossing of a single, isolated CME. We also
analyze the kinematics of the two CMEs in different cases, including
their expansion rate, and we discuss their expected geo-effectiveness.
---------------------------------------------------------
Title: Stability of Inverted Temperature Loops in the Quiet Corona
Authors: Huang, Zhenguang; Frazin, Richard A.; van der Holst, Bart;
Nuevo, Federico A.; Vasquez, Alberto M.; Manchester, Ward B., IV;
Sokolov, Igor V.; Gombosi, Tamas I.
2013shin.confE..85H Altcode:
Recent investigations of the quiet Corona have revealed the existence
of inverted temperature
