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Author name code: munoz-jaramillo
ADS astronomy entries on 2022-09-14
author:Munoz-Jaramillo, Andres

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Title: Comparing the Performance of a Solar Wind model from the Sun
    to 1 AU using Real and Synthetic Magnetograms
Authors: Henadhira Arachchige, Kalpa; Cohen, Ofer; Muñoz Jaramillo,
   Andrés; Yeates, Anthony R.
2022arXiv220813668H    Altcode:
  The input of the Solar wind models plays a significant role in
  accurate solar wind predictions at 1 AU. This work introduces a
  synthetic magnetogram produced from a dynamo model as an input for
  Magnetohydrodynamics (MHD) simulations. We perform a quantitative
  study that compares the Space Weather Modeling Framework (SWMF) results
  for the observed and the synthetic solar magnetogram input. For each
  case, we compare the results for Extreme Ultra-Violet (EUV) images and
  extract the simulation data along the earth trajectory to compare with
  in-situ observations. We initialize SWMF using the real and synthetic
  magnetogram for a set of Carrington Rotations (CR)s within the solar
  cycle 23 and 24. Our results help quantify the ability of dynamo models
  to be used as input to solar wind models and thus, provide predictions
  for the solar wind at 1 AU.

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Title: The Solaris Solar Polar MIDEX-Class Mission Concept: Revealing
    the Mysteries of the Sun's Poles
Authors: Hassler, Donald M.; Harra, Louise K.; Gibson, Sarah; Thompson,
   Barbara; Gusain, Sanjay; Berghmans, David; Linker, Jon; Basu, Sarbani;
   Featherstone, Nicholas; Hoeksema, J. Todd; Viall, Nicholeen; Newmark,
   Jeffrey; Munoz-Jaramillo, Andres; Upton, Lisa A.
2022cosp...44.1528H    Altcode:
  Solaris is an exciting, innovative & bold mission of discovery to
  reveal the mysteries of the Sun's poles. Solaris was selected for Phase
  A development as part of NASA's MIDEX program. Solaris builds upon
  the legacy of Ulysses, which flew over the solar poles, but Solaris
  provides an entirely new feature remote sensing, or IMAGING. Solaris
  will be the first mission to image the poles of the Sun from ~75
  degrees latitude and provide new insight into the workings of the
  solar dynamo and the solar cycle, which are at the foundation of our
  understanding of space weather and space climate. Solaris will also
  provide enabling observations for improved space weather research,
  modeling and prediction with time series of polar magnetograms and
  views of the ecliptic from above, providing a unique view of the
  corona, coronal dynamics, and CME eruption. To reach the Sun's poles,
  Solaris will first travel to Jupiter, and use Jupiter's gravity to
  slingshot out of the ecliptic plane, and fly over the Sun's poles
  at ~75 degrees latitude. Just as our understanding of Jupiter &
  Saturn were revolutionized by polar observations from Juno and Cassini,
  our understanding of the Sun will be revolutionized by Solaris.

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Title: A Machine-Learning Oriented Dataset for Forecasting SEP
    Occurrence and Properties
Authors: Moreland, Kimberly; Dayeh, Maher A.; Chatterjee, Subhamoy;
   Munoz-Jaramillo, Andres; Dayeh, Maher; Bain, Hazel
2022cosp...44.1151M    Altcode:
  We present a new parameter-rich dataset that is tailored for the
  forecasting of solar energetic particle (SEP) events. The dataset
  comprises numerous parameters from in situ and remote observatories. It
  contains over 18,000 flare events and their associated remote images,
  along with their measured X-ray, radio, proton, electron, upstream
  interplanetary (IP) plasma, and magnetic field properties. When
  available (i.e., positive SEP cases), associated SEP, coronal mass
  ejection, and shock properties are provided, in addition to numerous
  physics-based derived parameters. In situ data comes from multiple
  instruments onboard GOES, ACE, and other 1 au missions. Remote data
  comes from instruments on board SDO and SOHO and include full-disc
  magnetograms, EUV, and coronagraph images. Selection criteria for
  flare event classification and methods for calculating important
  SEP properties will be explained. Special consideration is given to
  data that is currently available in operational real-time or will be
  available in real-time on upcoming missions. The dataset has already
  been used in the development of a newly emerging model that forecasts
  the occurrence and subsequent properties of SEPs at 1 au.

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Title: Efficient labelling of solar flux evolution videos by a deep
    learning model
Authors: Chatterjee, Subhamoy; Muñoz-Jaramillo, Andrés; Lamb,
   Derek A.
2022NatAs...6..796C    Altcode: 2022NatAs.tmp..143C
  Machine learning is becoming a critical tool for the interrogation
  of large, complex data. Labelling, defined as the process of adding
  meaningful annotations, is a crucial step of supervised machine
  learning. However, labelling datasets is time consuming. Here we
  show that convolutional neural networks (CNNs) trained on crudely
  labelled astronomical videos can be leveraged to improve the quality
  of data labelling and reduce the need for human intervention. We
  use videos of the solar magnetic field that are divided into two
  classes—emergence or non-emergence of bipolar magnetic regions
  (BMRs)—on the basis of their first detection on the solar disk. We
  train CNNs using crude labels, manually verify, correct disagreements
  between the labelling and CNN, and repeat this process until convergence
  is reached. Traditionally, flux emergence labelling is done manually. We
  find that a high-quality labelled dataset derived through this iterative
  process reduces the necessary manual verification by 50%. Furthermore,
  by gradually masking the videos and looking for maximum changes in
  CNN inference, we locate BMR emergence time without retraining the
  CNN. This demonstrates the versatility of CNNs for simplifying the
  challenging task of labelling complex dynamic events.

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Title: Revisiting Christoph Scheiner's Sunspot Records: A New
    Perspective on Solar Activity of the Early Telescopic Era
Authors: Carrasco, V. M. S.; Muñoz-Jaramillo, A.; Gallego, M. C.;
   Vaquero, J. M.
2022ApJ...927..193C    Altcode:
  Christoph Scheiner was one of the most outstanding astronomers in the
  history of sunspot observations. His book, Rosa Ursina, is the reference
  work regarding the study of the earliest sunspot records. The sunspot
  observations compiled by Scheiner in Rosa Ursina and Prodomus, including
  records made by other observers, forms one of the main references
  of the observations known for that period-particularly around the
  1620s. Thus, his work is crucial to determine the solar activity level
  of the first solar cycles of the telescopic era. The number of sunspot
  groups recorded in Scheiner's documentary sources has been included
  in the existing sunspot group number databases. However, we have
  detected significant errors in the number of groups currently assigned
  to Scheiner's records. In this work, we reanalyze the information in
  Scheiner's source documents. Consequently, the standard 11 yr solar
  cycle shape for the second solar cycle of the telescopic era, which is
  not clear in previous studies, now becomes evident. In addition, the
  highest daily number of groups recorded during this cycle (eight groups)
  is 20% less than in the one included in the existing sunspot group
  number databases. Using the hypergeometrical probability distribution,
  we find that solar minima in 2008-2009 and 2018-2019 are comparable to
  the most probable solar activity level of the minimum around 1632. In
  particular, the estimated lower limit for the solar activity in 1632
  is even comparable with the solar activity level in 2008 and 2018.

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Title: Deep-SWIM: A few-shot learning approach to classify Solar
    WInd Magnetic field structures
Authors: Lamdouar, Hala; Sundaresan, Sairam; Jungbluth, Anna; Boro
   Saikia, Sudeshna; Camarata, Amanda Joy; Miles, Nathan; Scoczynski,
   Marcella; Stone, Mavis; Sarah, Anthony; Muñoz-Jaramillo, Andrés;
   Narock, Ayris; Szabo, Adam
2022arXiv220301184L    Altcode:
  The solar wind consists of charged particles ejected from the Sun into
  interplanetary space and towards Earth. Understanding the magnetic field
  of the solar wind is crucial for predicting future space weather and
  planetary atmospheric loss. Compared to large-scale magnetic events,
  smaller-scale structures like magnetic discontinuities are hard
  to detect but entail important information on the evolution of the
  solar wind. A lack of labeled data makes an automated detection of
  these discontinuities challenging. We propose Deep-SWIM, an approach
  leveraging advances in contrastive learning, pseudo-labeling and
  online hard example mining to robustly identify discontinuities in
  solar wind magnetic field data. Through a systematic ablation study,
  we show that we can accurately classify discontinuities despite
  learning from only limited labeled data. Additionally, we show that
  our approach generalizes well and produces results that agree with
  expert hand-labeling.

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Title: VizieR Online Data Catalog: SCO daily sunspot area measurements
    (1886-1940) (Carrasco+, 2021)
Authors: Carrasco, V. M. S.; Munoz-Jaramillo, A.; Nogales, J. M.;
   Gallego, M. C.; Vaquero, J. M.
2022yCat..22560038C    Altcode:
  The yearbooks published by the Stonyhurst
  College Observatory (SCO) are available online:
  http://www.geomag.bgs.ac.uk/data_service/data/yearbooks/sto.html See
  Section 2. <P />Fortunately, we know some details of the instruments
  used in these solar observations. An 8 inch (around 0.2m) refractor
  telescope was used to observe sunspots until 1893 (Stonyhurst College
  Observatory 1892). In 1893, that telescope was dismounted and replaced
  by a new 15-inch (~0.4m) refractor. In 1893, while the installation
  of the new telescope was finished, the sunspot drawings were carried
  out with a 6-inch (~0.15m) refractor. Moreover, the observatory also
  had another 7-inch Newtonian refractor and a 9 1/2 inch altazimuth
  reflector. In order to carry out the sunspot drawings, the observers
  at SCO put a light board at the eye end of the telescope and made
  the drawing from the projected image (Stonyhurst College Observatory
  1881). The diameter of the projected image was 10.5 inches (~0.26m). In
  the case of sunspots with special interest, an enlarged drawing was
  made on a scale of 30 inches (~0.76m) to the solar diameter. <P />(2
  data files).

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Title: Large Scale Collaborative Science: Lessons Learned from the
    Phase I COFFIES DRIVE Science Center
Authors: Hess Webber, Shea; Upton, Lisa; Munoz-Jaramillo, Andres;
   Hoeksema, J.; Bush, Rock; Lauben, Dave
2021AGUFMSH55D1863H    Altcode:
  The National Research Council published a report on Enhancing the
  Effectiveness of Team Science in 2015. This report identified 7
  fundamental challenges that large research teams, such as the
  NASA DRIVE Science Centers (DSC), might face including: high
  diversity of membership, deep knowledge integration, large size,
  goal misalignment, permeable boundaries, geographic dispersion,
  and high task interdependence. In Phase I, the COFFIES DSC formed
  a Center Effectiveness Team (CET) to identify and help overcome
  these and other unique challenges, including those introduced by the
  COVID-19 pandemic. CET members have focused on finding and exploring
  novel ways to align and direct the Science Teams with the goal of
  enabling breakthrough science. We will present the CET initiatives and
  implementations, and review the lessons learned for future large-scale
  science collaborations.

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Title: Comparing the Performance of a Solar Wind model from the Sun
    to 1 AU using Real and Synthetic Magnetograms
Authors: Henadhira Arachchige, Kalpa; Cohen, Ofer; Munoz-Jaramillo,
   Andres
2021AGUFMSH55C1846H    Altcode:
  We perform a quantitative study which compares the results of the Alfven
  Wave Solar Atmosphere Model (AWSoM) within the Space Weather Modeling
  Framework (SWMF). For selected Carrington Rotations, we drive the model
  by two different solar magnetogram inputs, the observed magnetogram,
  and a synthetic magnetogram produced by a dynamo model. We simulate the
  Solar Corona (SC) and the Inner Heliosphere (IH) domains using these
  SWMF modules. For each case, we compare the observed and simulated
  cases (real and synthetic magnetogram) using the model synthesized
  multi-wavelength EUV images. We also extract the simulation data
  from the IH domain along the earth trajectory to compare with OMNI
  observational data at 1 au. We initialize the model using the synoptic
  magnetogram (real magnetogram) and the surface fields maps produced
  by the dynamo model (synthetic magnetogram) for a set of Carrington
  rotations within the solar cycle 23 and 24. Our results help to quantify
  the ability of dynamo models to be used as input to solar wind models,
  and thus, provide predictions for the solar wind at 1AU.

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Title: Impact of Anomalous Active Regions on the Large Scale Magnetic
    Fields of the Solar Cycle
Authors: Pal, Shaonwita; Nandy, Dibyendu; Bhowmik, Prantika; Dash,
   Soumyaranjan; Mahajan, Sushant; Munoz-Jaramillo, Andres
2021AGUFMSH55D1878P    Altcode:
  Emergence of anomalous bipolar magnetic regions (combinations of
  anti-hale and anti-joy regions) on the solar surface can influence cycle
  to cycle variability and irregularities. We perform a comprehensive
  analysis of the dipole moment and polar field build up due to
  the appearance of anomalous active regions on the solar surface
  using a solar surface flux transport model. Our aim is to study the
  differences and the similarities between these anomalous regions and
  their effect in global solar cycle dynamics. Although these regions
  appear in small numbers, if they carry significant flux, they are
  found to significantly impact the polar field strength and thereby,
  the amplitude of future cycles.

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Title: Leveraging a Deep Neural Network to Efficiently Label Solar
    Flux Emergence Videos
Authors: Chatterjee, Subhamoy; Munoz-Jaramillo, Andres; Lamb, Derek
2021AGUFMNG45B0557C    Altcode:
  Machine learning is becoming a critical tool for interrogation of large
  complex data. However, labeling large datasets is time consuming. Here
  we show that convolutional neural networks (CNNs), trained on crudely
  labeled astronomical videos, can be leveraged to improve the quality
  of data labeling and reduce the need for human intervention. We use
  videos of the solar photospheric magnetic field, crudely labeled into
  two classes: emergence or non-emergence of large bipolar magnetic
  regions (BMRs) that have have the potential to drive space weather
  events. We train the CNN using crude labeling, manually verify,
  correct labeling vs. CNN disagreements, and repeat this process until
  convergence. This results in a high-quality labeled dataset requiring
  the manual verification of only ~50% of all videos. Furthermore,
  by gradually masking the videos and looking for maximum change in
  CNN inference, we locate BMR emergence time without retraining the
  CNN. This demonstrates the versatility of CNNs for simplifying the
  challenging task of labeling complex dynamic events.

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Title: Increasing reliability of Solar Energetic Particle forecast
    through calibration of neural network outcome
Authors: Chatterjee, Subhamoy; Munoz-Jaramillo, Andres; Bain, Hazel;
   Moreland, Kimberly Dianne; Dayeh, Maher
2021AGUFMSM51B..04C    Altcode:
  Solar Energetic Particles (SEPs) are among the crucial drivers of
  space weather in the near-Earth environment. Thus reliable forecast
  of SEPs is of immense value.We built a deep learning (DL) model to
  predict SEPs utilizing a rich remote sensing and in-situ database
  that is being discussed elsewhere in the meeting. Generally the
  probabilistic outcomes produced by such models do not correlate well
  with the observed frequency of events and thus lack in reliability to
  be used with confidence for real-time forecast as operational mode. We
  use a temperature scaling approach on a hold-out set to calibrate
  the probabilistic outcome of our trained DL model. We finally apply
  our calibrated model on a test-set and show that the calibration
  significantly improves the model reliability i.e. SEP probability
  matches SEP frequency much better across the probability bins.

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Title: Classification of Solar Wind Structures via Unsupervised
    Machine Learning
Authors: Stone, Mavis; Camarata, Amanda; Jungbluth, Anna;
   Munoz-Jaramillo, Andres; Lamdouar, Hala; Martins, Marcella; Miles,
   Nathan; Saikia, Sudeshna; Sundaresan, Sairam; Sarah, Anthony
2021AGUFMNG45B0572S    Altcode:
  The solar wind is a constant stream of plasma structured by the solar
  magnetic field that is radially ejected from our Sun to the boundaries
  of our solar system. Organizations such as NASA and ESA have gathered
  nearly half a century of data on solar wind, but much of it has yet
  to be analyzed for improved understanding on solar wind evolution. So
  far, heliophysicists have primarily focused on understanding specific
  structures such as interplanetary coronal mass ejections and large-scale
  discontinuities; however, there exist many statistically significant
  structures that have yet to be discovered. In this work, we create a
  new, unsupervised framework designed to catalog both known and unknown
  structures using magnetic field time series data from the three-year-old
  Parker Solar Probe. We combine iSAX indexing and HDB Scan clustering
  to identify, retrieve, and cluster similar magnetic field structures,
  a challenge that would otherwise be impossible. More specifically,
  we perform preliminary clustering on similar solar wind structures
  with 0.005% of the operations traditional clustering would normally
  require. Our method can be used on other time series data including,
  but not limited to: plasma velocity, density, and electron composition,
  all of which can offer further insight into space weather and its impact
  on Earth and our satellites. Additionally, the great size, detail, and
  level of organization of our catalog can expedite efforts to learn more
  about the origins and evolution of the solar wind. Beyond the scope of
  our work, this easily reproducible framework can be applied to other
  fields of research aiming to analyze large amounts of time series data.

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Title: Sunspot Catalog (1921-1935) and Area Series (1886-1940)
    from the Stonyhurst College Observatory
Authors: Carrasco, V. M. S.; Muñoz-Jaramillo, A.; Nogales, J. M.;
   Gallego, M. C.; Vaquero, J. M.
2021ApJS..256...38C    Altcode:
  A sunspot observation program was started at the end of the 19th century
  at the Stonyhurst College Observatory (hereafter SCO) by Father Perry,
  director of the observatory at that time. A digitization of the daily
  sunspot area series recorded in this observatory from 1886 to 1940
  (with a gap between 1889 and 1897) is provided in this work. This
  depicts one of the oldest sunspot area series available. A comparison
  of this series with contemporary area series made in other observatories
  shows that SCO generally recorded larger areas than those in some of the
  observatories of that time such as, for example, the Royal Greenwich
  Observatory (RGO). Furthermore, SCO published a sunspot group catalog
  for the period 1921-1935. We provide a machine-readable version of this
  catalog. We compared the SCO group number series with other sunspot
  data obtained from other observatories. In this case, for example, the
  RGO systematically recorded more groups than the SCO. We compared SCO
  and RGO area distribution functions obtaining the calibration constant
  between both data sets. We also obtained the butterfly diagram from the
  group latitudes recorded by SCO and compared the percentages of group
  types computed from the SCO catalog with those from Valencia Observatory
  (following the Cortie morphological classification of sunspot groups),
  identifying their similarities and differences.

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Title: Solar Anti-Hale Bipolar Magnetic Regions: A Distinct Population
    with Systematic Properties
Authors: Muñoz-Jaramillo, Andrés; Navarrete, Benjamín; Campusano,
   Luis E.
2021ApJ...920...31M    Altcode: 2022arXiv220311898M
  Besides their causal connection with long and short-term magnetic
  variability, solar bipolar magnetic regions are our chief source of
  insight into the location, size, and properties of large-scale toroidal
  magnetic structures in the solar interior. The great majority of these
  regions (≍95%) follow a systematic east-west polarity orientation
  (Hale's law) that reverses in opposite hemispheres and across even and
  odd cycles. These regions also present a systematic north-south polarity
  orientation (Joy's law) that helps build the poloidal field that seeds
  the new cycle. Exceptions to Hale's law are rare and difficult to study
  due to their low numbers. Here, we present a statistical analysis of the
  inclination (tilt) with respect to the equator of Hale versus anti-Hale
  regions spanning four solar cycles, considering two complementary
  tilt definitions adopted in previous studies. Our results show that
  anti-Hale regions belong to a separate population than Hale regions,
  suggesting a different originating mechanism. However, we find that
  anti-Hale region tilts present similar systematic tilt properties
  and similar latitudinal distributions to Hale regions, implying a
  strong connection between the two. We see this as evidence that they
  belong to a common toroidal flux system. We speculate that anti-Hale
  regions originate from poloidal field sheared and strengthened on the
  spot after the emergence of Hale regions with very strong poloidal
  contribution. Thus, they are not in contradiction with the idea of
  largely coherent toroidal flux systems inside the solar interior.

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Title: Improved Measurements of the Sun's Meridional Flow and
    Torsional Oscillation from Correlation Tracking on MDI and HMI
    Magnetograms
Authors: Mahajan, Sushant S.; Hathaway, David H.; Muñoz-Jaramillo,
   Andrés; Martens, Petrus C.
2021ApJ...917..100M    Altcode: 2021arXiv210707731M
  The Sun's axisymmetric flows, differential rotation, and meridional
  flow govern the dynamics of the solar magnetic cycle, and a variety of
  methods are used to measure these flows, each with its own strengths
  and weaknesses. Flow measurements based on cross-correlating images of
  the surface magnetic field have been made since the 1970s that require
  advanced numerical techniques that are capable of detecting movements
  of less than the pixel size in images of the Sun. We have identified
  several systematic errors in addition to the center-to-limb effect that
  influence previous measurements of these flows and propose numerical
  techniques that can minimize these errors by utilizing measurements
  of displacements at several time lags. Our analysis of line-of-sight
  magnetograms from the Michelson Doppler Imager on the ESA/NASA Solar
  and Heliospheric Observatory and the Helioseismic and Magnetic Imager
  on the NASA Solar Dynamics Observatory shows long-term variations in
  the meridional flow and differential rotation over two sunspot cycles
  from 1996 to 2020. These improved measurements can serve as vital
  inputs for solar dynamo and surface flux transport simulations.

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Title: Leveraging a Deep Neural Network to Efficiently Label Solar
    Flux Emergence Videos
Authors: Chatterjee, S.; Munoz-Jaramillo, A.; Lamb, D.
2021AAS...23812302C    Altcode:
  Machine learning can be an efficient approach to discover patterns
  from large datasets. Supervised learning techniques often surpass
  unsupervised approaches for performing classification tasks on complex
  data. However, labeling large datasets is a time consuming process. In
  this study, we show that a convolutional neural network(CNN), trained on
  crudely labeled time sequences of astronomical images, can be leveraged
  to improve the quality of datalabeling in a time efficient manner that
  minimizes human intervention. Furthermore, a CNN trained to determine
  if an event takes place within the image sequence can be re-purposed,
  without changes, to determine the time of the event occurrence.We
  use SoHO/MDI videos of the solar photospheric magnetic, approximately
  labeled into two classes: emergence or non-emergenceof large bipolar
  magnetic regions. The complex interaction of solar magnetic elements
  often limits the ability of conventional image-processing techniques to
  identify this emergence, especially near the solar limb. Our results
  demonstrate that big datasets do not need to be perfectly labeled for
  supervised learning. Instead, focusing only on false model inferences
  can refine labeling. We also test the limits of the detection ability
  of our network by resampling the data both spatially and temporally
  to simulate other instruments.

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Title: Cross-calibration, super-resolution, and uncertainty estimation
    of the conversion of MDI and GONG to HMI full-disk magnetograms
    using deep learning
Authors: Munoz-Jaramillo, A.; Jungbluth, A.; Gitiaux, X.; Wright,
   P.; Shneider, C.; Maloney, S.; Kalaitzis, A.; Baydin, A.; Gal, Y.;
   Deudon, M.
2021AAS...23812303M    Altcode:
  Over the past 50 years, a variety of instruments have obtained images
  of the Sun's magnetic field (magnetograms) to study its origin
  and evolution. While improvements in instrumentation have led to
  breakthroughs in our understanding of physical phenomena, differences
  between subsequent instruments such as resolution, noise, and saturation
  levels all introduce inhomogeneities into long-term data sets. This
  has proven to be an insurmountable obstacle for research applications
  that require high-resolution and homogeneous data spanning time frames
  longer than the lifetime of a single instrument. <P />Here we show
  that deep-learning-based super-resolution techniques can successfully
  up-sample and homogenize solar magnetic field images obtained both by
  space and ground-based instruments. In particular, we show the results
  of cross-calibrating and super-resolving MDI and GONG magnetograms
  to the characteristics of HMI. <P />We also discuss the importance
  of agreeing on a standardized set of training, validation, and test
  data, as well as metrics that enable the community to benchmark
  different approaches to collectively and quantitatively identify
  the best practices. This includes distributing test data within the
  broad heliophysics community. <P />Finally, we discuss our approach
  for making an empirical estimation of uncertainty and the importance
  that uncertainty estimation plays in the credibility and usefulness
  of deep learning applications in heliophysics.

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Title: Investigating the Polar Flux Budget with the Advective Flux
    Transport Model
Authors: Upton, L.; Munoz-Jaramillo, A.
2021AAS...23832805U    Altcode:
  The strength of the magnetic field at the Sun's poles near the time of
  a sunspot cycle minimum is a crucial component to the solar dynamo and
  is thought to determine the strength of the following solar activity
  cycle. Unfortunately, our knowledge of the polar magnetic field
  is limited to what can be gleaned from measurements taken from the
  ecliptic on the Sun-Earth line; a vantage point from which the dynamics
  of polar field evolution are not easily observable. Many surface flux
  transport models use a loss term, thought to represent the subduction
  of magnetic flux to the interior, in order to accurately reproduce the
  evolution of the polar fields. Others include the emergence of ephemeral
  active regions in the polar regions. We use the realistic Advective Flux
  Transport (AFT) model, in combination with HMI observations, to simulate
  the evolution of the Sun's polar magnetic fields for three different
  scenarios: pure flux transport, flux transport with subduction, and
  flux transport with ephemeral emergence. We show the impact of these
  different scenarios on the polar flux budget and discuss the advantages
  that a polar viewpoint, like that of the SOLARIS mission, will provide
  for measuring and understanding polar magnetic field evolution.

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Title: Deciphering the Deep Origin of Active Regions via Analysis
    of Magnetograms
Authors: Dikpati, Mausumi; McIntosh, Scott W.; Chatterjee, Subhamoy;
   Norton, Aimee A.; Ambroz, Pavel; Gilman, Peter A.; Jain, Kiran;
   Munoz-Jaramillo, Andres
2021ApJ...910...91D    Altcode:
  In this work, we derive magnetic toroids from surface magnetograms
  by employing a novel optimization method, based on the trust region
  reflective algorithm. The toroids obtained in this way are combinations
  of Fourier modes (amplitudes and phases) with low longitudinal
  wavenumbers. The optimization also estimates the latitudinal width of
  the toroids. We validate the method using synthetic data, generated
  as random numbers along a specified toroid. We compute the shapes and
  latitudinal widths of the toroids via magnetograms, generally requiring
  several m's to minimize residuals. A threshold field strength is
  chosen to include all active regions in the magnetograms for toroid
  derivation, while avoiding non-contributing weaker fields. Higher
  thresholds yield narrower toroids, with an m = 1 dominant pattern. We
  determine the spatiotemporal evolution of toroids by optimally weighting
  the amplitudes and phases of each Fourier mode for a sequence of five
  Carrington Rotations (CRs) to achieve the best amplitude and phases for
  the middle CR in the sequence. Taking more than five causes "smearing"
  or degradation of the toroid structure. While this method applies no
  matter the depth at which the toroids actually reside inside the Sun,
  by comparing their global shape and width with analogous patterns
  derived from magnetohydrodynamic (MHD) tachocline shallow water model
  simulations, we infer that their origin is at/near the convection zone
  base. By analyzing the "Halloween" storms as an example, we describe
  features of toroids that may have caused the series of space weather
  events in 2003 October-November. Calculations of toroids for several
  sunspot cycles will enable us to find similarities/differences in
  toroids for different major space weather events.

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Title: The Language of Stars
Authors: Berea, A.; Munoz-Jaramillo, A.
2021BAAS...53c1144B    Altcode:
  NASA Frontier Development Lab (FDL) is a research accelerator that
  brings together data scientists and space scientists to solve some
  of the most difficult space and planetary problems using AI. This
  project is a spin-off of one of the main challenges, that identified
  star spots in Kepler data. But in this spin-off project we are looking
  at applications of specific AI techniques (natural language processing
  — NLP) to time series (light curves) in order to identify both unique
  features and patterns in time series in general, and in light curves in
  particular. We both construct and derive informational building blocks
  that are characteristic to the light curves of the stars in a subset of
  Kepler data and we compare these methods to more traditional machine
  learning applications (clustering). We show how this new methodology,
  rooted in NLP, can be a good alternative for the analysis of light
  curves and potentially for identifying exoplanetary transit as unique
  "linguistic" features. <P />The idea for this project came from asking
  the following questions, one pertaining to advancing a potentially
  new methodology in machine learning, and another one pertaining to
  astrophysics: <P />1. Can we use NLP to discover features in time
  series? if yes, how good is it comparatively to other methods, such as
  clustering? <P />2. Can we create a "dictionary" of star features that
  we can use as a genetic code to catalogue and identify any star, and
  that we can also use to simulate stars that we have not yet observed? <P
  />Starting with these questions, we embarked on an exploratory research,
  to understand whether a duo of a combination of ML methods and an
  application to star light curves can help us discover features and
  patterns within time series, in general, and within light curves,
  in particular. The rationale or the big WHY of such methodological
  &amp; science specific exploration stems from a few facts that we
  tried to connect coherently: NLP is good at discovering patterns in
  messy/noisy, unstructured data (such as languages); NLP is great for
  creating vocabularies, dictionaries, taxonomies; NLP is also good at
  creating new and large texts (data) from small lists of dictionaries
  and vocabularies. Based on these assumptions, our first methodological
  challenge came from trying to understand the best method or algorithm
  to create textual data (for our NLP goals) from numeric data (from
  our given time series). In other words, the first step was to create
  the "words", "letters" or the "n-grams" from light curves data. For
  this proof of concept, we used 632 original Kepler light curves,
  with the idea to scale it up to analyze and parse more than 110K
  light curves, data available during the FDL program (summer 2020);
  if this proves successful, we aim to afterwards add TESS light curve
  data as well. The light curve data we used therefore consists of 632
  time series, collected over a period of about 4 years on a cadence of
  every 20 minutes. <P />We used 6 different methodologies to create
  6 different corpora from the entire dataset — each corpus is a
  collection of 632 individual "books", where each book/light curve
  is a sequence of n-grams that we created based on these methods:
  <P />1.1. Bin-based (large) — we binned the data in bins of 10 (1
  order of magnitude), and for each bin we assigned a "binXX" n-gram;
  <P />1.2. Bin-based (small) — we binned the data in bins of 100 (2
  orders of magnitude), and for each bin we assigned a "binXXX" n-gram;
  <P />1.3. Peaks and troughs — for each sequence of consecutive peaks
  and trough in the time series, we assigned "posXX" or "negXX" n-gram,
  where "pos" stands for the peak in the time series, "neg" stands for
  the trough in the time series, and XX is the number of consecutive
  peaks or troughs observed in the data; <P />1.4. PD clustering-based
  — this method is based on measurements of entropy and complexity in
  the time series; <P />1.5. Zipf distribution-based — in this method,
  we fitted a Zipf distribution to each star light curve and created the
  n-grams based on the rank of the frequency of the data given by the
  distribution. The Zipf Law is one of the most important laws observed in
  human languages, but also in physical phenomena such as earthquakes, and
  is scale invariant, a very important property for pattern detection in
  a wide range of scales; <P />1.6. 3-movement-based — in this method,
  we partitioned the data into 6 types of movements of any 3 consecutive
  data points in the light curves. <P />Entropy measurements. A first
  observation from our analyses has been that methods 1.1 and 1.2 show
  the Shannon entropy of the n-grams is the closest to the Shannon
  entropy of the light curves, and can be interpreted as the method
  that closest preserves the information from the light curve through
  the text transformation. Shannon entropy is one of the most important
  measures of information in natural language processing. <P />PRELIMINARY
  RESULTS. Clustering. We tried many clustering methods on the actual
  data, in order to extract features that we would a posteriori use
  for n-gram creation (i.e., unsupervised k-means clustering, knn,
  hierarchical, etc.). Out of all the tried clustering methods, the one
  that is also based on entropy and which we used in our n-gram method
  1.4, PD clustering, shows the most promising results in isolating
  specific features within the light curves. We also clustered based on
  the difference time series, and the difference isolates even better
  specific features in the light curves. <P />Topic Modeling. After
  creating the n-grams, we performed topic modeling (TM), an NLP specific
  method, that is grouping the n-grams within a corpus based on their
  probability of occurrence within a star. The TM method showed us which
  star features are most likely to occur next to each other across all
  632 light curves.

---------------------------------------------------------
Title: The Language of Stars
Authors: Berea, Anamaria; Munoz-Jaramillo, Andres
2021cosp...43E.533B    Altcode:
  NASA Frontier Development Lab (FDL) is a research accelerator that
  brings together data scientists and space scientists to solve some of
  the most difficult space and planetary problems using AI. This project
  is a spin-off of one of the main challenges, that identified star
  spots in Kepler data. But in this spin-off project we are looking at
  applications of specific AI techniques (natural language processing -
  NLP) to time series (light curves) in order to identify both unique
  features and patterns in time series in general, and in light curves in
  particular. We both construct and derive informational building blocks
  that are characteristic to the light curves of the stars in a subset of
  Kepler data and we compare these methods to more traditional machine
  learning applications (clustering). We show how this new methodology,
  rooted in NLP, can be a good alternative for the analysis of light
  curves and potentially for identifying exoplanetary transit as unique
  "linguistic" features.

---------------------------------------------------------
Title: Super-resolution of Solar Magnetograms
Authors: Wright, P. J.; Gitiaux, X.; Jungbluth, A.; Maloney, S.;
   Shneider, C.; Kalaitzis, A.; Baydin, A. G.; Deudon, M.; Gal, Y.;
   Munoz-Jaramillo, A.
2020AGUFMSH0440001W    Altcode:
  Over the past 50 years, a variety of instruments have obtained
  images of the Sun's magnetic field (magnetograms) to study its
  origin and evolution. While improvements in instrumentation have
  led to breakthroughs in our understanding of physical phenomena,
  differences between subsequent instruments such as resolution, noise,
  and saturation levels all introduce inhomogeneities into long-term data
  sets. This poses a significant issue for research applications that
  require high-resolution and homogeneous data spanning time frames longer
  than the lifetime of a single instrument. <P />As super-resolution is
  an ill-posed problem, multiple super-resolution outputs can explain a
  low-resolution input. Classical methods, such as bicubic upsampling,
  use only the information contained in the low-resolution image. However,
  in recent years it has been shown that a learning-based approach can
  constrain the non-trivial solution space by exploiting regularities
  within a specific distribution of images. <P />In this work, we
  cross-calibrate and super-resolve magnetic field data obtained by the
  Michelson Doppler Imager (MDI; 1024 x 1024 px) and the Helioseismic and
  Magnetic Imager (HMI; 4096 x 4096 px). These instruments overlap from
  2010 to 2011, resulting in approximately 9000 co-temporal observations
  of the same physical structures. Our deep learning model is trained on a
  subset of the overlapping data after initial pre-processing to correct
  for temporal and orbital differences between the instruments. <P />We
  evaluate the quality of the predictive output of the model with a series
  of performance metrics. These metrics include the distribution of the
  magnetic field and physical properties captured by the signed/unsigned
  field. Our approach also needs to quantify the certainty of predictions
  to be valuable to scientists. To address this, we estimate the posterior
  distribution of the super-resolved magnetic field by introducing Monte
  Carlo dropouts on each convolutional layer.

---------------------------------------------------------
Title: Derivation of Toroid Patterns from Analysis of Magnetograms
    And Inferring Their Deep-origin
Authors: Chatterjee, S.; Dikpati, M.; McIntosh, S. W.; Norton, A. A.;
   Ambroz, P.; Gilman, P.; Jain, K.; Munoz-Jaramillo, A.
2020AGUFMSH0020013C    Altcode:
  We employ a novel optimization method based on Trust Region Reflective
  algorithm to derive magnetic toroids from surface magnetograms. Toroids
  obtained are combinations of Fourier modes (amplitudes and phases)
  with low longitudinal wavenumbers. After validating the method using
  synthetic data generated as random numbers along a specified toroid,
  we compute shapes and latitudinal-widths of toroids from magnetograms,
  usually requiring several m 's to minimize residuals. By comparing
  properties of these toroids with patterns produced in the bottom
  toroidal band undergoing MHD evolution in a 3D thin-shell shallow-water
  type model, we infer their deep origin at/near convention-zone's base
  or tachocline. A threshold field-strength is chosen to include all
  active regions in magnetograms for toroid derivation, while avoiding
  non-contributing weaker fields. Higher thresholds yield narrower
  toroids, with m = 1 dominant, implying that stronger active regions
  are erupting from the core of the toroids at bottom. We determine the
  spatio-temporal evolution of toroids by optimally weighting amplitudes
  and phases of each Fourier mode for a sequence of 5 Carrington Rotations
  (CRs) to get the best amplitude and phases for the middle CR in the
  sequence. Taking more than 5 causes 'smearing' or degradation of toroid
  structure. As an example case, we analyze 'Halloween' storms toroids,
  and describe the features that might have caused the series of space
  weather events in October-November of 2003. We compare features of
  these toroids with analogous patterns derived from model-output. To find
  similarities/differences in toroids for different major space weather
  events, we will analyze long-term magnetograms for several solar cycles.

---------------------------------------------------------
Title: RotNet: Fast and Scalable Estimation of Stellar Rotation
    Periods Using Convolutional Neural Networks
Authors: Johnson, J. Emmanuel; Sundaresan, Sairam; Daylan, Tansu;
   Gavilan, Lisseth; Giles, Daniel K.; Ishitani Silva, Stela; Jungbluth,
   Anna; Morris, Brett; Muñoz-Jaramillo, Andrés
2020arXiv201201985J    Altcode:
  Magnetic activity in stars manifests as dark spots on their surfaces
  that modulate the brightness observed by telescopes. These light
  curves contain important information on stellar rotation. However, the
  accurate estimation of rotation periods is computationally expensive
  due to scarce ground truth information, noisy data, and large parameter
  spaces that lead to degenerate solutions. We harness the power of deep
  learning and successfully apply Convolutional Neural Networks to regress
  stellar rotation periods from Kepler light curves. Geometry-preserving
  time-series to image transformations of the light curves serve as
  inputs to a ResNet-18 based architecture which is trained through
  transfer learning. The McQuillan catalog of published rotation periods
  is used as ansatz to groundtruth. We benchmark the performance of
  our method against a random forest regressor, a 1D CNN, and the
  Auto-Correlation Function (ACF) - the current standard to estimate
  rotation periods. Despite limiting our input to fewer data points (1k),
  our model yields more accurate results and runs 350 times faster than
  ACF runs on the same number of data points and 10,000 times faster than
  ACF runs on 65k data points. With only minimal feature engineering
  our approach has impressive accuracy, motivating the application of
  deep learning to regress stellar parameters on an even larger scale

---------------------------------------------------------
Title: Erratum: "A Machine-learning Data Set Prepared from the NASA
    Solar Dynamics Observatory Mission" (2019, ApJS, 242, 7)
Authors: Galvez, Richard; Fouhey, David F.; Jin, Meng; Szenicer,
   Alexandre; Muñoz-Jaramillo, Andrés; Cheung, Mark C. M.; Wright,
   Paul J.; Bobra, Monica G.; Liu, Yang; Mason, James; Thomas, Rajat
2020ApJS..250...38G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Using Deep Learning to Produce a Labelled Solar Flux Emergence
    Data-set
Authors: Chatterjee, S.; Munoz-Jaramillo, A.; Lamb, D.
2020SPD....5120703C    Altcode:
  With the advent of space-based observatories, we are facing a big data
  problem in astronomy. Machine learning serves as an efficient approach
  to discover patterns from such data. Supervised learning techniques
  (e.g. neural networks) often surpass unsupervised approaches for
  performing classification tasks on complex data. However, labeling
  large datasets is an onerous and time-consuming process that is often
  prohibitively expensive. In this study, we show that a deep neural
  network trained on crudely labeled astronomical data can be leveraged
  to improve the quality of data labeling in a time efficient manner
  that minimizes human intervention. We use SoHO/MDI magnetic evolution
  videos, approximately labeled for emergence/non-emergence. We train a
  convolutional neural network (CNN) to perform the classification task
  and only manually verify the labels of videos, which are incorrectly
  classified by the model. We iterate this process until there is no
  change in classification accuracy. After performing a full manual
  verification, we find that the large majority of videos where the model
  succeeded were indeed properly labeled. We also show that apart from
  performing the classification task, the model is able to identify when
  emergence occurs. Our results demonstrate that big datasets do not need
  to be perfectly labeled initially for supervised learning. Instead,
  focusing only on failed examples can refine the labeling. This subset
  is by definition smaller than the full set and thus requires less
  manual work. Solar magnetic flux-emergence is often associated with
  space weather events that can potentially have a disruptive impact on
  long-distance communications. The complex interaction of solar magnetic
  elements often limits the ability of conventional image-processing
  techniques to identify flux emergence. Our CNN's ability to identify
  both the emergence event and its starting time hints at the possibility
  of using deep learning to enable flux emergence prediction.

---------------------------------------------------------
Title: Validating and Cross-Calibrating Long-term Solar Cycle Data
    for Driving Solar Cycle Models
Authors: Munoz-Jaramillo, A.; Vaquero, J. M.
2019AGUFMSM31C3550M    Altcode:
  The Sun is the main driver of variability in the interplanetary
  environment and Earth's upper atmosphere. This influence is felt across
  a multiplicity of spatial and temporal scales ranging from seconds
  to decades. Long-term variability requires homogeneous observational
  surveys covering long periods of time, which are incompatible with
  modern funding cycles and are seriously undervalued by governmental
  agencies, especially in the United States. For this reason, it is often
  necessary to piece multiple heterogeneous instruments and surveys with
  different experimental design, characteristics, and systematics. Here
  we discuss an array of historical data sets (magnetic, optical and in
  the form of reduced time series) that give us direct insight on the
  long-term evolution of solar activity and the efforts that are being
  made to piece them together into homogenous composites that can be
  used to constrain and drive models of solar activity. We highlight the
  importance of ensuring that historical surveys are properly preserved
  and modernized for future generations, and discuss important aspects
  of documenting them so that future users can take better advantage of
  the insight they provide.

---------------------------------------------------------
Title: International Scientific Coordination on Space Weather:
    A COSPAR Panel on Space Weather Perspective
Authors: Kuznetsova, M.; Bisi, M. M.; Kusano, K.; Fuller-Rowell,
   T. J.; Mann, I.; Belehaki, A.; Minow, J. I.; Munoz-Jaramillo, A.;
   Masson, A.; Bruinsma, S.; Bisi, M. M.; Kuznetsova, M. M.; Temmer, M.;
   Opgenoorth, H. J.; Belehaki, A.; Bruinsma, S.; Glover, A.; Heynderickx,
   D.; Linker, J.; Mann, I. R.; Murray, S. A.; Nandy, D.
2019AGUFMSM31C3543K    Altcode:
  The understanding and prediction of space-weather phenomena and
  their respective impact(s) on society have been widely-acknowledged
  as an international challenge and something that requires a global
  coordination and focus. In order to address this need to form
  more-formal worldwide collaboration and coordination, and to maximise
  return on such efforts (particularly scientifically), the Committee
  on Space Research (COSPAR) Panel on Space Weather (PSW) has created a
  network of International Space Weather Action Teams (ISWATs). <P />The
  COSPAR PSW ISWAT initiative is capitalising on established efforts by
  engaging existing national and international "teams" and "facilitates"
  to form individual ISWATs that are being grouped into clusters
  by domains/themes related to different aspects of solar/coronal,
  heliospheric, ionospheric/atmospheric, and planetary space-weather
  phenomena. The initiative also includes overarching themes such as
  dealing with large data sets and model/scientific validations. The
  ISWAT initiative places a strong encouragement for scientists to go
  beyond their funding borders to form ISWATs better suited to address
  challenges that one individual or small group/team may not be able to
  address alone. <P />The ISWAT initiative serves as a global hub for
  community coordinated topical focused collaborations and as a global
  community voice for the next generation of both scientific and strategic
  planning - this includes an update of the COSPAR/ILWS space weather
  scientific roadmap (to transform the roadmap into a living document)
  and to potentially provide an operational roadmap in parallel. <P
  />This presentation will re-introduce the ISWAT initiative, review
  its current status and plans for community-wide campaigns, highlight
  the overarching current plans for PSW, and place a focus on two key
  space-weather areas: the ambient heliosphere/background solar wind
  (designated as ISWAT theme H1) and CME structure, evolution and
  propagation through heliosphere (designated as ISWAT theme H2).

---------------------------------------------------------
Title: Visualization of the challenges and limitations of the
    long-term sunspot number record
Authors: Muñoz-Jaramillo, Andrés; Vaquero, José M.
2019NatAs...3..205M    Altcode: 2018NatAs...3..205M; 2022arXiv220311919M
  The solar cycle periodically reshapes the magnetic structure
  and radiative output of the Sun and determines its impact on the
  heliosphere roughly every 11 years. Besides this main periodicity,
  it shows century-long variations (including periods of abnormally low
  solar activity called grand minima). The Maunder Minimum (1645-1715) has
  generated significant interest as the archetype of a grand minimum in
  magnetic activity for the Sun and other stars, suggesting a potential
  link between the Sun and changes in terrestrial climate. Recent
  reanalyses of sunspot observations have yielded a conflicted view on
  the evolution of solar activity during the past 400 years (a steady
  increase versus a constant level). This has ignited a concerted
  community-wide effort to understand the depth of the Maunder Minimum
  and the subsequent secular evolution of solar activity. The goal of
  this Perspective is to review recent work that uses historical data to
  estimate long-term solar variability, and to provide context to users of
  these estimates that may not be aware of their limitations. We propose
  a clear visual guide than can be used to easily assess observational
  coverage for different periods, as well as the level of disagreement
  between currently proposed sunspot group number series.

---------------------------------------------------------
Title: Sunspot Characteristics at the Onset of the Maunder Minimum
    Based on the Observations of Hevelius
Authors: Carrasco, V. M. S.; Vaquero, J. M.; Gallego, M. C.;
   Muñoz-Jaramillo, A.; de Toma, G.; Galaviz, P.; Arlt, R.; Senthamizh
   Pavai, V.; Sánchez-Bajo, F.; Villalba Álvarez, J.; Gómez, J. M.
2019ApJ...886...18C    Altcode: 2021arXiv210309495C
  An analysis of the sunspot observations made by Hevelius during
  1642-1645 is presented. These records are the only systematic sunspot
  observations just before the Maunder Minimum (MM). We have studied
  different phenomena meticulously recorded by Hevelius after translating
  the original Latin texts. We reevaluate the observations of sunspot
  groups by Hevelius during this period and obtain an average value
  7% greater than that calculated from his observations given in the
  current group database. Furthermore, the average of the active day
  fraction obtained in this work from Hevelius’s records previous to
  the MM is significantly greater than the solar activity level obtained
  from Hevelius’s sunspot observations made during the MM (70% versus
  30%). We also present the butterfly diagram obtained from the sunspot
  positions recorded by Hevelius for the period 1642-1645. It can be
  seen that no hemispheric asymmetry exists during this interval,
  in contrast with the MM. Hevelius noted a ∼3-month period that
  appeared to lack sunspots in early 1645 that gave the first hint of
  the impending MM. Recent studies claim that the MM was not a grand
  minimum period, speculating that astronomers of that time, due to the
  Aristotelian ideas, did not record all sunspots that they observed,
  producing thus an underestimation of the solar activity level. However,
  we show that the good quality of the sunspot records made by Hevelius
  indicates that his reports of sunspots were true to the observations.

---------------------------------------------------------
Title: Probabilistic Super-Resolution of Solar Magnetograms:
    Generating Many Explanations and Measuring Uncertainties
Authors: Gitiaux, Xavier; Maloney, Shane A.; Jungbluth, Anna; Shneider,
   Carl; Wright, Paul J.; Güneş Baydin, Atılım; Deudon, Michel; Gal,
   Yarin; Kalaitzis, Alfredo; Muñoz-Jaramillo, Andrés
2019arXiv191101486G    Altcode:
  Machine learning techniques have been successfully applied to
  super-resolution tasks on natural images where visually pleasing results
  are sufficient. However in many scientific domains this is not adequate
  and estimations of errors and uncertainties are crucial. To address this
  issue we propose a Bayesian framework that decomposes uncertainties
  into epistemic and aleatoric uncertainties. We test the validity of
  our approach by super-resolving images of the Sun's magnetic field
  and by generating maps measuring the range of possible high resolution
  explanations compatible with a given low resolution magnetogram.

---------------------------------------------------------
Title: Single-Frame Super-Resolution of Solar Magnetograms:
    Investigating Physics-Based Metrics \&amp; Losses
Authors: Jungbluth, Anna; Gitiaux, Xavier; Maloney, Shane A.; Shneider,
   Carl; Wright, Paul J.; Kalaitzis, Alfredo; Deudon, Michel; Güneş
   Baydin, Atılım; Gal, Yarin; Muñoz-Jaramillo, Andrés
2019arXiv191101490J    Altcode:
  Breakthroughs in our understanding of physical phenomena have
  traditionally followed improvements in instrumentation. Studies of the
  magnetic field of the Sun, and its influence on the solar dynamo and
  space weather events, have benefited from improvements in resolution
  and measurement frequency of new instruments. However, in order to fully
  understand the solar cycle, high-quality data across time-scales longer
  than the typical lifespan of a solar instrument are required. At
  the moment, discrepancies between measurement surveys prevent
  the combined use of all available data. In this work, we show that
  machine learning can help bridge the gap between measurement surveys
  by learning to \textbf{super-resolve} low-resolution magnetic field
  images and \textbf{translate} between characteristics of contemporary
  instruments in orbit. We also introduce the notion of physics-based
  metrics and losses for super-resolution to preserve underlying physics
  and constrain the solution space of possible super-resolution outputs.

---------------------------------------------------------
Title: A deep learning virtual instrument for monitoring extreme UV
    solar spectral irradiance
Authors: Szenicer, Alexandre; Fouhey, David F.; Munoz-Jaramillo,
   Andres; Wright, Paul J.; Thomas, Rajat; Galvez, Richard; Jin, Meng;
   Cheung, Mark C. M.
2019SciA....5.6548S    Altcode:
  Measurements of the extreme ultraviolet (EUV) solar spectral irradiance
  (SSI) are essential for understanding drivers of space weather effects,
  such as radio blackouts, and aerodynamic drag on satellites during
  periods of enhanced solar activity. In this paper, we show how to
  learn a mapping from EUV narrowband images to spectral irradiance
  measurements using data from NASA's Solar Dynamics Observatory obtained
  between 2010 to 2014. We describe a protocol and baselines for measuring
  the performance of models. Our best performing machine learning (ML)
  model based on convolutional neural networks (CNNs) outperforms other
  ML models, and a differential emission measure (DEM) based approach,
  yielding average relative errors of under 4.6% (maximum error over
  emission lines) and more typically 1.6% (median). We also provide
  evidence that the proposed method is solving this mapping in a way that
  makes physical sense and by paying attention to magnetic structures
  known to drive EUV SSI variability.

---------------------------------------------------------
Title: The need for active region disconnection in 3D kinematic
    dynamo simulations
Authors: Whitbread, T.; Yeates, A. R.; Muñoz-Jaramillo, A.
2019A&A...627A.168W    Altcode: 2019arXiv190702762W
  In this paper we address a discrepancy between the surface flux
  evolution in a 3D kinematic dynamo model and a 2D surface flux transport
  model that has been closely calibrated to the real Sun. We demonstrate
  that the difference is due to the connectivity of active regions to
  the toroidal field at the base of the convection zone, which is not
  accounted for in the surface-only model. Initially, we consider the
  decay of a single active region, firstly in a simplified Cartesian 2D
  model and subsequently the full 3D model. By varying the turbulent
  diffusivity profile in the convection zone, we find that increasing
  the diffusivity - so that active regions are more rapidly disconnected
  from the base of the convection zone - improves the evolution of the
  surface field. However, if we simulate a full solar cycle, we find
  that the dynamo is unable to sustain itself under such an enhanced
  diffusivity. This suggests that in order to accurately model the solar
  cycle, we must find an alternative way to disconnect emerging active
  regions, whilst conserving magnetic flux.

---------------------------------------------------------
Title: Historical astronomical data: urgent need for preservation,
    digitization enabling scientific exploration
Authors: Pevtsov, Alexei; Griffin, Elizabeth; Grindlay, Jonathan;
   Kafka, Stella; Bartlett, Jennifer; Usoskin, Ilya; Mursula, Kalevi;
   Gibson, Sarah; Pillet, Valentín; Burkepile, Joan; Webb, David; Clette,
   Frédéric; Hesser, James; Stetson, Peter; Muñoz-Jaramillo, Andres;
   Hill, Frank; Bogart, Rick; Osborn, Wayne; Longcope, Dana
2019BAAS...51c.190P    Altcode: 2019arXiv190304839P; 2019astro2020T.190P
  This white paper emphasizes critical importance of preservation,
  digitization and scientific exploration of historical astronomical
  data. It outlines the rationale, provides examples of new science
  with such data, and reviews the potential losses to science if nothing
  it done.

---------------------------------------------------------
Title: A Machine-learning Data Set Prepared from the NASA Solar
    Dynamics Observatory Mission
Authors: Galvez, Richard; Fouhey, David F.; Jin, Meng; Szenicer,
   Alexandre; Muñoz-Jaramillo, Andrés; Cheung, Mark C. M.; Wright,
   Paul J.; Bobra, Monica G.; Liu, Yang; Mason, James; Thomas, Rajat
2019ApJS..242....7G    Altcode: 2019arXiv190304538G
  In this paper, we present a curated data set from the NASA
  Solar Dynamics Observatory (SDO) mission in a format suitable for
  machine-learning research. Beginning from level 1 scientific products
  we have processed various instrumental corrections, down-sampled
  to manageable spatial and temporal resolutions, and synchronized
  observations spatially and temporally. We illustrate the use of this
  data set with two example applications: forecasting future extreme
  ultraviolet (EUV) Variability Experiment (EVE) irradiance from present
  EVE irradiance and translating Helioseismic and Magnetic Imager
  observations into Atmospheric Imaging Assembly observations. For
  each application, we provide metrics and baselines for future model
  comparison. We anticipate this curated data set will facilitate
  machine-learning research in heliophysics and the physical sciences
  generally, increasing the scientific return of the SDO mission. This
  work is a direct result of the 2018 NASA Frontier Development Laboratory
  Program. Please see the Appendix for access to the data set, totaling
  6.5TBs.

---------------------------------------------------------
Title: DeepEM: Demonstrating a Deep Learning Approach to DEM Inversion
Authors: Wright, Paul J.; Cheung, Mark C. M.; Thomas, Rajat; Galvez,
   Richard; Szenicer, Alexandre; Jin, Meng; Muñoz-Jaramillo, Andrés;
   Fouhey, David
2019zndo...2587015W    Altcode:
  DeepEM is a (supervised) deep learning approach to differential
  emission measure (DEM) inversion that is currently under
  development on GitHub.  This first release coincides with the
  version of DeepEM demonstrated in Chapter 4 of the Machine Learning,
  Statistics, and Data Mining for Heliophysics e-book (Bobra & Mason
  2018). Within the chapter (and the code provided here, DeepEM.ipynb)
  we demonstrate how a simple implementation of supervised learning
  can be used to reconstruct DEM maps from SDO/AIA data. Caveats
  of this simple implementation and future work are also discussed.
  The Machine Learning, Statistics, and Data Mining for Heliophysics
  e-book can be accessed at https://helioml.github.io/HelioML/,
  and the interactive DeepEM notebook (Chapter 4) is located at
  https://helioml.github.io/HelioML/04/1/notebook.

---------------------------------------------------------
Title: The Extended Solar Cycle: Muddying the Waters of Solar/Stellar
    Dynamo Modeling Or Providing Crucial Observational Constraints?
Authors: Srivastava, Abhishek K.; McIntosh, Scott W.; Arge,
   N.; Banerjee, Dipankar; Dikpati, Mausumi; Dwivedi, Bhola N.;
   Guhathakurta, Madhulika; Karak, B. B.; Leamon, Robert J.; Matthew,
   Shibu K.; Munoz-Jaramillo, Andres; Nandy, D.; Norton, Aimee; Upton,
   L.; Chatterjee, S.; Mazumder, Rakesh; Rao, Yamini K.; Yadav, Rahul
2018FrASS...5...38S    Altcode: 2018arXiv180707601S
  In 1844 Schwabe discovered that the number of sunspots increased and
  decreased over a period of about 11 years, that variation became known
  as the sunspot cycle. Almost eighty years later, Hale described the
  nature of the Sun's magnetic field, identifying that it takes about 22
  years for the Sun's magnetic polarity to cycle. It was also identified
  that the latitudinal distribution of sunspots resembles the wings of
  a butterfly showing migration of sunspots in each hemisphere that
  abruptly start at mid-latitudes (about ±35(o) ) towards the Sun's
  equator over the next 11 years. These sunspot patterns were shown
  to be asymmetric across the equator. In intervening years, it was
  deduced that the Sun (and sun-like stars) possess magnetic activity
  cycles that are assumed to be the physical manifestation of a dynamo
  process that results from complex circulatory transport processes in
  the star's interior. Understanding the Sun's magnetism, its origin
  and its variation, has become a fundamental scientific objective
  the distribution of magnetism, and its interaction with convective
  processes, drives various plasma processes in the outer atmosphere
  that generate particulate, radiative, eruptive phenomena and shape the
  heliosphere. In the past few decades, a range of diagnostic techniques
  have been employed to systematically study finer scale magnetized
  objects, and associated phenomena. The patterns discerned became
  known as the “Extended Solar Cycle” (ESC). The patterns of the ESC
  appeared to extend the wings of the activity butterfly back in time,
  nearly a decade before the formation of the sunspot pattern, and to
  much higher solar latitudes. In this short review, we describe their
  observational patterns of the ESC and discuss possible connections
  to the solar dynamo as we depart on a multi-national collaboration to
  investigate the origins of solar magnetism through a blend of archived
  and contemporary data analysis with the goal of improving solar dynamo
  understanding and modeling.

---------------------------------------------------------
Title: Solar EUV Spectral Irradiance by Deep Learning
Authors: Wright, Paul; Galvez, Richard; Szenicer, Alexandre; Thomas,
   Rajat; Jin, Meng; Fouhey, David; Cheung, Mark; Munoz-Jaramillo,
   Andres; Mackintosh, Graham
2018csc..confE..90W    Altcode:
  Extreme UV (EUV) radiation from the Sun's transition region and
  corona is an important driver for the energy balance of the Earth's
  thermosphere and ionosphere. To characterise and monitor solar forcing
  on this system and associated space weather impacts, the EUV Variability
  Experiment (EVE) instrument onboard NASA's Solar Dynamics Observatory
  (SDO) was designed to measure solar spectral irradiance (SSI) in the
  0.1 to 105 nm wavelength range. As the result of an electrical short,
  the MEGS-A component of EVE stopped delivering SSI data in the 5 - 35
  nm wavelength range in May 2014. We demonstrate how a Residual Neural
  Network (ResNet) augmented with a Multi-Layer Perceptron (MLP) can
  fill this gap using narrowband UV and EUV images from the Atmospheric
  Imaging Assembly (AIA) on SDO. As a performance benchmark, we also show
  how our deep learning approach outperforms a physics model based on
  differential emission measure inversions. This work was performed at
  NASA's Frontier Development Lab, a public-private initiative to apply
  AI techniques to accelerate space science discovery and exploration.

---------------------------------------------------------
Title: How Many Active Regions Are Necessary to Predict the Solar
    Dipole Moment?
Authors: Whitbread, T.; Yeates, A. R.; Muñoz-Jaramillo, A.
2018ApJ...863..116W    Altcode: 2018arXiv180701617W
  We test recent claims that the polar field at the end of Cycle 23 was
  weakened by a small number of large, abnormally oriented regions, and
  investigate what this means for solar cycle prediction. We isolate the
  contribution of individual regions from magnetograms for Cycles 21, 22,
  and 23 using a 2D surface flux transport model, and find that although
  the top ∼10% of contributors tend to define sudden large variations
  in the axial dipole moment, the cumulative contribution of many weaker
  regions cannot be ignored. To recreate the axial dipole moment to a
  reasonable degree, many more regions are required in Cycle 23 than
  in Cycles 21 and 22 when ordered by contribution. We suggest that
  the negative contribution of the most significant regions of Cycle
  23 could indeed be a cause of the weak polar field at the following
  cycle minimum and the low-amplitude Cycle 24. We also examine the
  relationship between a region’s axial dipole moment contribution and
  its emergence latitude, flux, and initial axial dipole moment. We find
  that once the initial dipole moment of a given region has been measured,
  we can predict the long-term dipole moment contribution using emergence
  latitude alone.

---------------------------------------------------------
Title: A Two Dimensional Prediction of Solar Cycle 25
Authors: Munoz-Jaramillo, A.; Martens, P. C.
2017AGUFMSH13A2469M    Altcode:
  To this date solar cycle most cycle predictions have focused on the
  forecast of solar cycle amplitude and cycle bell-curve shape. However,
  recent intriguing observational results suggest that all solar cycles
  follow the same longitudinal path regardless of their amplitude,
  and have a very similar decay once they reach a sufficient level
  of maturity. Cast in the light of our current understanding, these
  results suggest that the toroidal fields inside the Sun are subject
  to a very high turbulent diffusivity (of the order of magnitude of
  mixing-length estimates), and their equatorward propagation is driven
  by a steady meridional flow. Assuming this is the case, we will revisit
  the relationship between the polar fields at minimum and the amplitude
  of the next cycle and deliver a new generation of polar-field based
  predictions that include the depth of the minimum, as well as the
  latitude and time of the first active regions of solar cycle 25.

---------------------------------------------------------
Title: Evolution of Our Understanding of the Solar Dynamo During
    Solar Cycle 24
Authors: Munoz-Jaramillo, A.
2017AGUFMSH11C..01M    Altcode:
  Solar cycle 24 has been an exciting cycle for our understanding of
  the solar dynamo: 1. It was the first cycle for which dynamo based
  predictions were ever used teaching us valuable lessons. 2. It has given
  us the opportunity to observe a deep minimum and a weak cycle with a
  high level of of observational detail . 3. It is full of breaktrhoughs
  in anelastic MHD dynamo simulations (regular cycles, buoyant flux-tubes,
  mounder-like events). 4. It has seen the creation of bridges between the
  kinematic flux-transport and anelastic MHD approaches. 5. It has ushered
  a new generation of realistic surface flux-transport simulations 6. We
  have achieved significant observational progress in our understanding
  of solar cycle propagation. The objective of this talk is to highlight
  some of the most important results, giving special emphasis on what
  they have taught us about solar cycle predictability.

---------------------------------------------------------
Title: Modeling Geomagnetic Variations using a Machine Learning
    Framework
Authors: Cheung, C. M. M.; Handmer, C.; Kosar, B.; Gerules, G.;
   Poduval, B.; Mackintosh, G.; Munoz-Jaramillo, A.; Bobra, M.; Hernandez,
   T.; McGranaghan, R. M.
2017AGUFMSM23A2591C    Altcode:
  We present a framework for data-driven modeling of Heliophysics time
  series data. The Solar Terrestrial Interaction Neural net Generator
  (STING) is an open source python module built on top of state-of-the-art
  statistical learning frameworks (traditional machine learning methods as
  well as deep learning). To showcase the capability of STING, we deploy
  it for the problem of predicting the temporal variation of geomagnetic
  fields. The data used includes solar wind measurements from the OMNI
  database and geomagnetic field data taken by magnetometers at US
  Geological Survey observatories. We examine the predictive capability
  of different machine learning techniques (recurrent neural networks,
  support vector machines) for a range of forecasting times (minutes
  to 12 hours). STING is designed to be extensible to other types
  of data. We show how STING can be used on large sets of data from
  different sensors/observatories and adapted to tackle other problems
  in Heliophysics.

---------------------------------------------------------
Title: Parameter optimization for surface flux transport models
Authors: Whitbread, T.; Yeates, A. R.; Muñoz-Jaramillo, A.; Petrie,
   G. J. D.
2017A&A...607A..76W    Altcode: 2017arXiv170801098W
  Accurate prediction of solar activity calls for precise calibration
  of solar cycle models. Consequently we aim to find optimal parameters
  for models which describe the physical processes on the solar surface,
  which in turn act as proxies for what occurs in the interior and provide
  source terms for coronal models. We use a genetic algorithm to optimize
  surface flux transport models using National Solar Observatory (NSO)
  magnetogram data for Solar Cycle 23. This is applied to both a 1D model
  that inserts new magnetic flux in the form of idealized bipolar magnetic
  regions, and also to a 2D model that assimilates specific shapes of
  real active regions. The genetic algorithm searches for parameter
  sets (meridional flow speed and profile, supergranular diffusivity,
  initial magnetic field, and radial decay time) that produce the best
  fit between observed and simulated butterfly diagrams, weighted by
  a latitude-dependent error structure which reflects uncertainty in
  observations. Due to the easily adaptable nature of the 2D model, the
  optimization process is repeated for Cycles 21, 22, and 24 in order
  to analyse cycle-to-cycle variation of the optimal solution. We find
  that the ranges and optimal solutions for the various regimes are in
  reasonable agreement with results from the literature, both theoretical
  and observational. The optimal meridional flow profiles for each regime
  are almost entirely within observational bounds determined by magnetic
  feature tracking, with the 2D model being able to accommodate the
  mean observed profile more successfully. Differences between models
  appear to be important in deciding values for the diffusive and decay
  terms. In like fashion, differences in the behaviours of different
  solar cycles lead to contrasts in parameters defining the meridional
  flow and initial field strength.

---------------------------------------------------------
Title: Polar Facular Observations by the Zurich Observatory: A Window
    to the Evolution of the Polar Fields during the Weakest Cycles of
    the Last 200 Years
Authors: Vargas-Acosta, Juan Pablo; Munoz-Jaramillo, Andres; Vargas
   Dominguez, Santiago; Svalgaard, Leif
2017SPD....48.0501V    Altcode:
  The solar polar magnetic fields are believed to be a surface
  manifestation of the large-scale field that acts as the seed for
  each solar cycle. Because of this, they have received a lot of recent
  attention as the best proxy for solar cycle prediction.Polar magnetic
  fields have been measured systematically since the 1970s and polar
  facular counts (which are directly correlated with polar field strength)
  have been used to infer the evolution of the polar fields going back to
  1906. However, this period does not cover the solar minima of cycle 12
  and 13 which preceded the weakest cycles of the last 200 years. These
  cycles are of great interest due to their similarity with solar cycle
  24, which was preceded by the deepest minimum observed so far during
  the space age.Here we present the results of a project to count polar
  faculae using recently digitized and released observations taken by
  the Zurich Observatory (1887 to 1937). These observations have the
  potential of extending our proxy for the polar fields further back
  into this period of great interest and help us test the validity of
  our understanding.

---------------------------------------------------------
Title: The Harm that Underestimation of Uncertainty Does to Our
Community: A Case Study Using Sunspot Area Measurements
Authors: Munoz-Jaramillo, Andres
2017SPD....4820704M    Altcode:
  Data products in heliospheric physics are very often provided
  without clear estimates of uncertainty. From helioseismology in
  the solar interior, all the way to in situ solar wind measurements
  beyond 1AU, uncertainty estimates are typically hard for users to
  find (buried inside long documents that are separate from the data
  products), or simply non-existent.There are two main reasons why
  uncertainty measurements are hard to find:1. Understanding instrumental
  systematic errors is given a much higher priority inside instrumental
  teams.2. The desire to perfectly understand all sources of uncertainty
  postpones indefinitely the actual quantification of uncertainty in our
  measurements.Using the cross calibration of 200 years of sunspot area
  measurements as a case study, in this presentation we will discuss the
  negative impact that inadequate measurements of uncertainty have on
  users, through the appearance of toxic and unnecessary controversies,
  and data providers, through the creation of unrealistic expectations
  regarding the information that can be extracted from their data. We
  will discuss how empirical estimates of uncertainty represent a very
  good alternative to not providing any estimates at all, and finalize
  by discussing the bare essentials that should become our standard
  practice for future instruments and surveys.

---------------------------------------------------------
Title: Update on a Solar Magnetic Catalog Spanning Four Solar Cycles
Authors: Vargas-Acosta, Juan Pablo; Munoz-Jaramillo, Andres; Vargas
   Dominguez, Santiago; Werginz, Zachary; DeLuca, Michael D.; Longcope,
   Dana; Harvey, J. W.; Windmueller, John; Zhang, Jie; Martens, Petrus C.
2017SPD....4811202V    Altcode:
  Bipolar magnetic regions (BMRs) are the cornerstone of solar
  cycle propagation, the building blocks that give structure to the
  solar atmosphere, and the origin of the majority of space weather
  events. However, in spite of their importance, there is no homogeneous
  BMR catalog spanning the era of systematic solar magnetic field
  measurements. Here we present the results of an ongoing project to
  address this deficiency applying the Bipolar Active Region Detection
  (BARD) code to magnetograms from the 512 Channel of the Kitt Peak
  Vaccum Telescope, SOHO/MDI, and SDO/HMI.The BARD code automatically
  identifies BMRs and tracks them as they are rotated by differential
  rotation. The output of the automatic detection is supervised by a human
  observer to correct possible mistakes made by the automatic algorithm
  (like incorrect pairings and tracking mislabels). Extra passes are made
  to integrate fragmented regions as well as to balance the flux between
  BMR polarities. At the moment, our BMR database includes nearly 10,000
  unique objects (detected and tracked) belonging to four separate solar
  cycles (21-24).

---------------------------------------------------------
Title: Mi Gauss es su Gauss: Lessons from Cross-Calibrating 40 years
    of Full Disk Magnetograms
Authors: Werginz, Zachary; Munoz-Jaramillo, Andres; Martens, Petrus
   C.; Harvey, J. W.
2017SPD....4811102W    Altcode:
  Full-disk line-of-sight magnetograms from the Kitt Peak Vacuum Telescope
  (KPVT) are a highly valuable, but underutilized, source of data for
  understanding long-term solar variability. Here we present the results
  of a project for obtaining a cross-callibrated series of magnetograms
  spanning 40 years including KPVT (512 and SPMG), SOHO/MDI and SDO/HMI
  magnetographs. The biggest challenge we face is empirically identifying
  a calibration factor and estimate of uncertainty between instruments
  with little temporal overlap.Here we propose a method that fragments
  magnetograms into spherical quadrangles bounded by latitudes and
  longitudes and calculates various information such as total area, mean
  flux density, and distance from disk center. Our main assumption is that
  the Sun does not change significantly over daily time periods.First
  a magnetogram to be calibrated is differentially rotated to match
  a reference magnetogram in time. Then the smaller magnetogram is
  interpolated into the larger one to account for sub-pixel heliographic
  coordinates. We then produce equally spaced bands of latitude and
  longitude determined from a fragmentation parameter. These are used
  to map out regions on each magnetogram that are expected to relay
  the same information. Our efforts to cross-calibrate lead to results
  that vary with fragmentation parameters, the difference in time of
  selected magnetograms, and distance from disk center.Given that this
  cross-callibrated series will be made publically available, we are
  looking for constructive criticism, suggestions, and feedback. Please
  join us in making these data as good as they can be.

---------------------------------------------------------
Title: Addressing Systematic Errors in Correlation Tracking on
    HMI Magnetograms
Authors: Mahajan, Sushant S.; Hathaway, David H.; Munoz-Jaramillo,
   Andres; Martens, Petrus C.
2017SPD....4820702M    Altcode:
  Correlation tracking in solar magnetograms is an effective method to
  measure the differential rotation and meridional flow on the solar
  surface. However, since the tracking accuracy required to successfully
  measure meridional flow is very high, small systematic errors have a
  noticeable impact on measured meridional flow profiles. Additionally,
  the uncertainties of this kind of measurements have been historically
  underestimated, leading to controversy regarding flow profiles at
  high latitudes extracted from measurements which are unreliable
  near the solar limb.Here we present a set of systematic errors we
  have identified (and potential solutions), including bias caused by
  physical pixel sizes, center-to-limb systematics, and discrepancies
  between measurements performed using different time intervals. We have
  developed numerical techniques to get rid of these systematic errors
  and in the process improve the accuracy of the measurements by an order
  of magnitude.We also present a detailed analysis of uncertainties in
  these measurements using synthetic magnetograms and the quantification
  of an upper limit below which meridional flow measurements cannot be
  trusted as a function of latitude.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Polar network index for the solar
    cycle studies (Priyal+, 2014)
Authors: Priyal, M.; Banerjee, D.; Karak, B. B.; Munoz-Jaramillo,
   A.; Ravindra, B.; Choudhuri, A. R.; Singh, J.
2017yCat..17939004P    Altcode:
  The spatial resolution of the Ca K spectroheliograms taken at
  Kodaikanal (hereafter KKL) is about 2 arcsec and the exit slit of the
  spectroheliograph yields a spectral window of 0.5 Å centered at the
  Ca-K line at 3933.67 Å. Ermoli et al. (2009ApJ...698.1000E) pointed
  out that the Kodaikanal archive hosts the longest homogeneous record,
  with fewer variations in spatial resolution. The earlier version of the
  8 bit data at Kodaikanal is sufficient to study those plage area with
  high intensity contrast, but does not provide the required photometric
  accuracy to properly identify the network structures because of the
  small intensity contrast of these features. Therefore, we have designed
  and developed two digitizer units, using a 1 m labsphere with an exit
  port of 350 mm which provides a stable and uniform source of light
  with less than 1% variation from the center to the edge of the light
  source. The CCD camera with 4kx4k format, a pixel size of 15 u square,
  and a 16 bit read out, operating at temperature of -100°C, was used
  to digitize the images. The Ca-K network can be clearly seen because
  of the high spatial resolution of digitization (0.86 arcsec). <P />(4
  data files).

---------------------------------------------------------
Title: A Detailed Reconstruction of Solar Activity During the
    Maunder Minimum
Authors: Munoz-Jaramillo, A.; Sanchez-Carrasco, V.; Vaquero, J. M.
2016AGUFMSH43D2589M    Altcode:
  Besides its decadal modulation, the solar cycle presents long-term
  secular changes in the amplitude of adjacent cycles that drive
  long-term changes in the heliospheric environment and have been
  suggested to drive long-term changes in terrestrial seasonal
  weather. The best well known of these secular changes is the Maunder
  Minimum (1645-1715), which coincided with an interval of very cold
  winters in Europe. Unfortunately, this period is characterized by a
  significant lack of telescopic observations and thus suffers from a
  very high level of observational uncertainty. In this presentation we
  will discuss recent efforts to increase the observational reliability
  of observations during the Maunder Minimum, by taking advantage of
  observational redundance, the analysis of these observations to place
  strict constraints on solar activity during the Maunder Minimum,
  by comparing with modern observations, and the implications these
  results have for our understanding of the solar dynamo.

---------------------------------------------------------
Title: Development of a Homogenous Database of Bipolar Active Regions
    Spanning Four Cycles
Authors: Munoz-Jaramillo, A.; Werginz, Z. A.; Vargas-Acosta, J. P.;
   DeLuca, M. D.; Vargas-Dominguez, S.; Lamb, D. A.; DeForest, C. E.;
   Longcope, D. W.; Martens, P.
2016AGUFMSH11A2219M    Altcode:
  The solar cycle can be understood as a process that alternates the
  large-scale magnetic field of the Sun between poloidal and toroidal
  configurations. Although the process that transitions the solar cycle
  between toroidal and poloidal phases is still not fully understood,
  theoretical studies, and observational evidence, suggest that this
  process is driven by the emergence and decay of bipolar magnetic
  regions (BMRs) at the photosphere. Furthermore, the emergence of
  BMRs at the photosphere is the main driver behind solar variability
  and solar activity in general; making the study of their properties
  doubly important for heliospheric physics. However, in spite of their
  critical role, there is still no unified catalog of BMRs spanning
  multiple instruments and covering the entire period of systematic
  measurement of the solar magnetic field (i.e. 1975 to present).In
  this presentation we discuss an ongoing project to address this
  deficiency by applying our Bipolar Active Region Detection (BARD)
  code on full disk magnetograms measured by the 512 (1975-1993) and
  SPMG (1992-2003) instruments at the Kitt Peak Vacuum Telescope (KPVT),
  SOHO/MDI (1996-2011) and SDO/HMI (2010-present). First we will discuss
  the results of our revitalization of 512 and SPMG KPVT data, then
  we will discuss how our BARD code operates, and finally report the
  results of our cross-callibration across instruments.The corrected
  and improved KPVT magnetograms will be made available through the
  National Solar Observatory (NSO) and Virtual Solar Observatory (VSO),
  including updated synoptic maps produced by running the corrected KPVT
  magnetograms though the SOLIS pipeline. The homogeneous active region
  database will be made public by the end of 2017 once it has reached
  a satisfactory level of quality and maturity. The Figure shows all
  bipolar active regions present in our database (as of Aug 2016) colored
  according to the instrument where they were detected. The image also
  includes the names of the NSF-REU students in charge of the supervision
  of the detection algorithm and the year in which they worked on the
  catalog. Marker size is indicative of the total active region flux.

---------------------------------------------------------
Title: The best of both worlds: Using automatic detection and limited
    human supervision to create a homogenous magnetic catalog spanning
    four solar cycles
Authors: Muñoz-Jaramillo, Andres; Werginz, Zachary; Vargas-Acosta,
   Juan Pablo; DeLuca, Michael; Windmueller, J. C.; Zhang, Jie; Longcope,
   Dana; Lamb, Derek; DeForest, Craig; Vargas-Domínguez, Santiago;
   Harvey, Jack; Martens, Piet
2016bida.conf.3194M    Altcode: 2022arXiv220311908M
  Bipolar magnetic regions (BMRs) are the cornerstone of solar
  variability. They are tracers of the large-scale magnetic processes
  that give rise to the solar cycle, shapers of the solar corona,
  building blocks of the large-scale solar magnetic field, and significant
  contributors to the free-energetic budget that gives rise to flares and
  coronal mass ejections. Surprisingly, no homogeneous catalog of BMRs
  exists today, in spite of the existence of systematic measurements of
  the magnetic field since the early 1970's. The purpose of this work is
  to address this deficiency by creating a homogenous catalog of BMRs
  from the 1970's until the present. For this purpose, in this paper
  we discuss the strengths and weaknesses of the automatic and manual
  detection of BMRs and how both methods can be combined to form the basis
  of our Bipolar Active Region Detection (BARD) code and its supporting
  human supervision module. At present, the BARD catalog contains more
  than 10,000 unique BMRs tracked and characterized during every day
  of their observation. Here we also discuss our future plans for the
  creation of an extended multi-scale magnetic catalog combining the
  SWAMIS and BARD catalogs.

---------------------------------------------------------
Title: Advances on Our Understanding of Solar Cycle Propagation
    and Predictability
Authors: Muñoz-Jaramillo, Andrés
2016usc..confE..88M    Altcode:
  As solar cycle 24 winds down and we start looking forward to the coming
  cycle 25, we are steadily approaching the time in which a new host
  of solar cycle predictions will be made. The point of this talk is to
  highlight some of the most important advances in our understanding of
  cycle propagation and its predictability (made since the last round
  of cycle predictions). In particular, this presentation will focus
  on theoretical and observational evidence in favor of a dynamo that
  relies on active region emergence and decay for its operation, and on
  evidence of a causal disconnection that takes place between one cycle
  and the next (making inter-cyclic prediction difficult)

---------------------------------------------------------
Title: Developing a Solar Magnetic Catalog Spanning Four Cycles
Authors: Werginz, Zachary; Munoz-Jaramillo, Andres; DeLuca, Michael
   D.; Vargas Acosta, Juan Pablo; Vargas Dominguez, Santiago; Zhang,
   Jie; Longcope, Dana; Martens, Petrus C.
2016SPD....4740502W    Altcode:
  Bipolar magnetic regions (BMRs) are the cornerstone of solar
  cycle propagation, the building blocks that give structure to the
  solar atmosphere, and the origin of the majority of space weather
  events. However, in spite of their importance, there is no homogeneous
  BMR catalog spanning the era of systematic solar magnetic field
  measurements. Here we present the results of an ongoing project to
  address this deficiency applying the Bipolar Active Region Detection
  (BARD) code to magnetograms from the 512 Channel of the Kitt Peak Vaccum
  Telescope, SOHO/MDI, and SDO/HMI.The BARD code automatically identifies
  BMRs and tracks them as they are rotated by differential rotation. The
  output of the automatic detection is supervised by a human observer
  to correct possible mistakes made by the automatic algorithm (like
  incorrect pairings and tracking mislabels). Extra passes are made to
  integrate fragmented regions as well as to balance the flux between
  BMR polarities. At the moment, our BMR database includes 6,885 unique
  objects (detected and tracked) belonging to four separate solar cycles
  (21-24).

---------------------------------------------------------
Title: An Emerging Magnetic Flux Catalog for SOHO/MDI
Authors: Lamb, Derek; Munoz-Jaramillo, Andres; DeForest, Craig
2016SPD....4730701L    Altcode:
  We present a catalog of emerging magnetic flux events covering
  the entirety of the 15-year-long SOHO/MDI 96-minute magnetogram
  dataset. Such a catalog has myriad uses in studies of the solar
  dynamo and solar cycle. Our catalog is designed to mimic as nearly
  as possible the Emerging Flux region catalog produced for SDO/HMI,
  allowing continuity across missions and solar cycles. We will present
  details of the algorithm for identifying emerging flux events, special
  considerations for MDI as opposed to HMI, detailed examples of some
  detected emerging flux regions, and a brief overview of statistics
  of the entire catalog. The catalog will be available for querying
  through the Heliophysics Event Knowledgebase, as well as for direct
  downloading from Southwest Research Institute. This work has been
  supported by NASA Grant NNX14AJ67G through the Heliophysics Data
  Environment Enhancements program.

---------------------------------------------------------
Title: Where Do Data Go When They Die? Attaining Data Salvation
    Through the Establishment of a Solar Dynamo Dataverse
Authors: Munoz-Jaramillo, Andres
2016SPD....4740801M    Altcode:
  The arrival of a highly interconnected digital age with practically
  limitless data storage capacity has brought with it a significant
  shift in which scientific data is stored and distributed (i.e. from
  being in the hands of a small group of scientists to being openly and
  freely distributed for anyone to use). However, the vertiginous speed
  at which hardware, software, and the nature of the internet changes
  has also sped up the rate at which data is lost due to formatting
  obsolescence and loss of access.This poster is meant to advertise the
  creation of a highly permanent data repository (within the context of
  Harvard's Dataverse), curated to contain datasets of high relevance
  for the study, and prediction of the solar dynamo, solar cycle, and
  long-term solar variability. This repository has many advantages over
  traditional data storage like the assignment of unique DOI identifiers
  for each database (making it easier for scientist to directly cite
  them), and the automatic versioning of each database so that all data
  are able to attain salvation.

---------------------------------------------------------
Title: Contextualizing Solar Cycle 24: Report on the Development of
    a Homogenous Database of Bipolar Active Regions Spanning Four Cycles
Authors: Munoz-Jaramillo, A.; Werginz, Z. A.; DeLuca, M. D.;
   Vargas-Acosta, J. P.; Longcope, D. W.; Harvey, J. W.; Martens, P.;
   Zhang, J.; Vargas-Dominguez, S.; DeForest, C. E.; Lamb, D. A.
2015AGUFMSH33D..06M    Altcode:
  The solar cycle can be understood as a process that alternates the
  large-scale magnetic field of the Sun between poloidal and toroidal
  configurations. Although the process that transitions the solar cycle
  between toroidal and poloidal phases is still not fully understood,
  theoretical studies, and observational evidence, suggest that this
  process is driven by the emergence and decay of bipolar magnetic
  regions (BMRs) at the photosphere. Furthermore, the emergence of
  BMRs at the photosphere is the main driver behind solar variability
  and solar activity in general; making the study of their properties
  doubly important for heliospheric physics. However, in spite of their
  critical role, there is still no unified catalog of BMRs spanning
  multiple instruments and covering the entire period of systematic
  measurement of the solar magnetic field (i.e. 1975 to present).In
  this presentation we discuss an ongoing project to address this
  deficiency by applying our Bipolar Active Region Detection (BARD)
  code on full disk magnetograms measured by the 512 (1975-1993) and
  SPMG (1992-2003) instruments at the Kitt Peak Vacuum Telescope (KPVT),
  SOHO/MDI (1996-2011) and SDO/HMI (2010-present). First we will discuss
  the results of our revitalization of 512 and SPMG KPVT data, then we
  will discuss how our BARD code operates, and finally report the results
  of our cross-callibration.The corrected and improved KPVT magnetograms
  will be made available through the National Solar Observatory (NSO)
  and Virtual Solar Observatory (VSO), including updated synoptic maps
  produced by running the corrected KPVT magnetograms though the SOLIS
  pipeline. The homogeneous active region database will be made public
  by the end of 2017 once it has reached a satisfactory level of quality
  and maturity. The Figure shows all bipolar active regions present in
  our database (as of Aug 2015) colored according to the sign of their
  leading polarity. Marker size is indicative of the total active region
  flux. Anti-Hale regions are shown using solid markers.

---------------------------------------------------------
Title: The Minimum of Solar Cycle 23: As Deep as It Could Be?
Authors: Muñoz-Jaramillo, Andrés; Senkpeil, Ryan R.; Longcope,
   Dana W.; Tlatov, Andrey G.; Pevtsov, Alexei A.; Balmaceda, Laura A.;
   DeLuca, Edward E.; Martens, Petrus C. H.
2015ApJ...804...68M    Altcode: 2015arXiv150801222M
  In this work we introduce a new way of binning sunspot group data
  with the purpose of better understanding the impact of the solar
  cycle on sunspot properties and how this defined the characteristics
  of the extended minimum of cycle 23. Our approach assumes that
  the statistical properties of sunspots are completely determined
  by the strength of the underlying large-scale field and have no
  additional time dependencies. We use the amplitude of the cycle
  at any given moment (something we refer to as activity level) as a
  proxy for the strength of this deep-seated magnetic field. We find
  that the sunspot size distribution is composed of two populations:
  one population of groups and active regions and a second population
  of pores and ephemeral regions. When fits are performed at periods
  of different activity level, only the statistical properties of the
  former population, the active regions, are found to vary. Finally,
  we study the relative contribution of each component (small-scale
  versus large-scale) to solar magnetism. We find that when hemispheres
  are treated separately, almost every one of the past 12 solar minima
  reaches a point where the main contribution to magnetism comes from
  the small-scale component. However, due to asymmetries in cycle phase,
  this state is very rarely reached by both hemispheres at the same
  time. From this we infer that even though each hemisphere did reach
  the magnetic baseline, from a heliospheric point of view the minimum
  of cycle 23 was not as deep as it could have been.

---------------------------------------------------------
Title: The Minimum of Solar Cycle 23: As Deep as It Could Be?
Authors: Munoz-Jaramillo, Andres; Senkpeil, Ryan; Longcope, Dana;
   Tlatov, Andrey; Pevtsov, Alexei A.; Balmaceda, Laura; DeLuca, Edward
   E.; Martens, Petrus C.
2015TESS....130803M    Altcode:
  After a lull lasting more than 60 years of seemly uniform solar minima,
  the solar minimum of solar cycle 23 came as a great surprise due to its
  depth, duration, and record lows in a wide variety of solar activity
  indices and solar wind properties. One of the consequence of such an
  event is the revival of the interest in extreme minima, grand minima,
  and the identification of a solar basal state of minimum magnetic
  activity.In this presentation we will discuss a new way of binning
  sunspot group data, with the purpose of better understanding the impact
  of the solar cycle on sunspot properties, and how this defined the
  characteristics of the extended minimum of cycle 23. Our main result
  is centered around the fact that the sunspot size distribution is
  composed of two populations, a population of groups and active regions,
  and second of pores and ephemeral regions. We find that only the
  properties of the former population, the active regions, is found to
  vary with the solar cycle, while the propeties of pores and ephemeral
  regions does not.Taking advantage of our statistical characterization
  we probe the question of the solar baseline magnetism. We find that,
  when hemispheres are treated separately, almost every one of the past
  12 solar minima reaches such a point. However, due to asymmetries in
  cycle phase, the basal state is very rarely reached by both hemispheres
  at the same time. From this we infer that, even though each hemisphere
  did reach the magnetic baseline, from a heliospheric point of view
  the minimum of cycle 23 was not as deep as it could have been.

---------------------------------------------------------
Title: Vitalizing four solar cycles of Kitt Peak synoptic magnetograms
Authors: Harvey, John; Munoz-Jaramillo, Andres
2015TESS....111102H    Altcode:
  Solar magnetism spans many decades of spatial and temporal
  scales. Studies of the larger end of these ranges requires frequent
  observations of the full solar disk over long durations. To aid
  investigations of the solar cycle and individual active region
  evolution, nearly daily magnetograms have been observed from Kitt Peak
  during solar cycles 20-23. These data were used in real time for space
  weather predictions, and archived observations have so far served more
  than 1500 refereed research publications. Some of the observations
  suffered from various instrumental problems. We report ongoing efforts
  to restore and correct observations from 1970-2003 in order to maximize
  the scientific value of the observations. The main improvements are
  reductions of certain instrumental noise, signal biases, and imperfect
  scanning geometry. The improved data will be used the make synchronic
  and diachronic synoptic maps, a catalog of active region properties,
  and estimates of tracer flow patterns.In addition to base funding
  from NSF, NASA and NOAA provided substantial support of the Kitt Peak
  synoptic observations.

---------------------------------------------------------
Title: Small-scale and Global Dynamos and the Area and Flux
Distributions of Active Regions, Sunspot Groups, and Sunspots:
    A Multi-database Study
Authors: Muñoz-Jaramillo, Andrés; Senkpeil, Ryan R.; Windmueller,
   John C.; Amouzou, Ernest C.; Longcope, Dana W.; Tlatov, Andrey G.;
   Nagovitsyn, Yury A.; Pevtsov, Alexei A.; Chapman, Gary A.; Cookson,
   Angela M.; Yeates, Anthony R.; Watson, Fraser T.; Balmaceda, Laura A.;
   DeLuca, Edward E.; Martens, Petrus C. H.
2015ApJ...800...48M    Altcode: 2014arXiv1410.6281M
  In this work, we take advantage of 11 different sunspot group,
  sunspot, and active region databases to characterize the area
  and flux distributions of photospheric magnetic structures. We
  find that, when taken separately, different databases are better
  fitted by different distributions (as has been reported previously
  in the literature). However, we find that all our databases can be
  reconciled by the simple application of a proportionality constant,
  and that, in reality, different databases are sampling different
  parts of a composite distribution. This composite distribution
  is made up by linear combination of Weibull and log-normal
  distributions—where a pure Weibull (log-normal) characterizes the
  distribution of structures with fluxes below (above) 10<SUP>21</SUP>Mx
  (10<SUP>22</SUP>Mx). Additionally, we demonstrate that the Weibull
  distribution shows the expected linear behavior of a power-law
  distribution (when extended to smaller fluxes), making our results
  compatible with the results of Parnell et al. We propose that this is
  evidence of two separate mechanisms giving rise to visible structures
  on the photosphere: one directly connected to the global component of
  the dynamo (and the generation of bipolar active regions), and the other
  with the small-scale component of the dynamo (and the fragmentation of
  magnetic structures due to their interaction with turbulent convection).

---------------------------------------------------------
Title: Automatic vs. Human Detection of Bipolar Magnetic Regions:
    Using the Best of Both Worlds
Authors: Munoz-Jaramillo, A.; DeLuca, M. D.; Windmueller, J. C.;
   Longcope, D. W.
2014AGUFMSH34A..04M    Altcode:
  The solar cycle can be understood as a process that alternates the
  large-scale magnetic field of the Sun between poloidal and toroidal
  configurations. Although the process that transitions the solar cycle
  between toroidal and poloidal phases is still not fully understood,
  theoretical studies, and observational evidence, suggest that this
  process is driven by the emergence and decay of bipolar magnetic
  regions (BMRs) at the photosphere. Furthermore, the emergence of
  BMRs at the photosphere is the main driver behind solar variability
  and solar activity in general; making the study of their properties
  doubly important for heliospheric physics. However, in spite of their
  critical role, there is still no unified catalog of BMRs spanning
  multiple instruments and covering the entire period of systematic
  measurement of the solar magnetic field (i.e. 1975 to present).One
  of the interesting aspects of the detection of BMRs is that, due to
  the time and spatial scales of interest, it is tractable for both
  human observers and automatic detection algorithms. This makes it
  ideal for comparative studies of the advantages and failing of both
  approaches. In this presentation we will compare three different BMR
  catalogs, reduced from magnetograms taken by SOHO/MDI, using human,
  automatic, and hybrid methods of detection. The focus will be the
  comparative performance between the three methods, their merits, and
  disadvantages, and the lessons that can be applied to other imaging
  data sets.

---------------------------------------------------------
Title: Polar Network Index as a Magnetic Proxy for the Solar Cycle
    Studies
Authors: Priyal, Muthu; Banerjee, Dipankar; Karak, Bidya Binay;
   Muñoz-Jaramillo, Andrés; Ravindra, B.; Choudhuri, Arnab Rai;
   Singh, Jagdev
2014ApJ...793L...4P    Altcode: 2014arXiv1407.4944P
  The Sun has a polar magnetic field which oscillates with the 11 yr
  sunspot cycle. This polar magnetic field is an important component
  of the dynamo process which operates in the solar convection zone and
  produces the sunspot cycle. We have direct systematic measurements of
  the Sun's polar magnetic field only from about the mid-1970s. There are,
  however, indirect proxies which give us information about this field
  at earlier times. The Ca-K spectroheliograms taken at the Kodaikanal
  Solar Observatory during 1904-2007 have now been digitized with 4k
  × 4k CCD and have higher resolution (~0.86 arcsec) than the other
  available historical data sets. From these Ca-K spectroheliograms,
  we have developed a completely new proxy (polar network index,
  hereafter PNI) for the Sun's polar magnetic field. We calculate PNI
  from the digitized images using an automated algorithm and calibrate
  our measured PNI against the polar field as measured by the Wilcox
  Solar Observatory for the period 1976-1990. This calibration allows
  us to estimate the polar fields for the earlier period up to 1904. The
  dynamo calculations performed with this proxy as input data reproduce
  reasonably well the Sun's magnetic behavior for the past century.

---------------------------------------------------------
Title: Statistical Constraints on Joy's Law
Authors: Amouzou, Ernest C.; Munoz-Jaramillo, Andres; Martens, Petrus
   C.; DeLuca, Edward E.
2014AAS...22421829A    Altcode:
  Using sunspot data from the observatories at Mt. Wilson and Kodaikanal,
  active region tilt angles are analyzed for different active region
  sizes and latitude bins. A number of similarly-shaped statistical
  distributions were fitted to the data using maximum likelihood
  estimation. In all cases, we find that the statistical distribution
  best describing the number of active regions at a given tilt angle is a
  Laplace distribution with the form (2β)<SUP>-1</SUP>*exp(-|x-μ|/β),
  with 2° ≤ μ ≤ 11°, and 10° ≤ β ≤ 40°.

---------------------------------------------------------
Title: From the Tachocline Into the Heliosphere: Coupling a 3D
    kinematic dynamo to the CCMC
Authors: Munoz-Jaramillo, Andres; Yeates, Anthony R; Martens, Petrus
   C.; DeLuca, Edward E.
2014AAS...22421103M    Altcode:
  During the last decade, axisymmetric kinematic dynamo models have
  contributed greatly to our understanding of the solar cycle. However,
  with the advent of more powerful computers the limitation to axisymmetry
  has been lifted. Here we present a 3D kinematic dynamo model where
  active regions are driven by velocity perturbations calibrated to
  reproduce observed active region properties (including the size and
  flux of active regions, and the distribution of tilt angle with
  latitude), resulting in a more consistent treatment of flux-tube
  emergence in kinematic dynamo models than artificial flux deposition. We
  demonstrate how this technique can be used to assimilate active region
  observations obtained from the US National Solar Observatory/Kitt Peak
  (NSO/KP) synoptic magnetograms and how our model couples naturally
  with heliospheric models, paving the way for the simultaneous study
  of the evolution of the magnetic field in the solar interior as well
  as its impact on the heliosphere.

---------------------------------------------------------
Title: From the tachocline into the heliosphere: coupling a 3D
    kinematic dynamo to coronal models
Authors: Yeates, Anthony; Munoz-Jaramillo, Andres
2014cosp...40E3715Y    Altcode:
  During the last decade, axisymmetric kinematic dynamo models have
  contributed greatly to our understanding of the solar cycle. However,
  with the advent of more powerful computers the limitation to
  axisymmetry has been lifted. Here we present a 3D kinematic dynamo
  model where active regions are driven by velocity perturbations
  calibrated to reproduce observed active region properties (including
  the size and flux of active regions, and the distribution of tilt
  angle with latitude), resulting in a more consistent treatment of
  flux-tube emergence in kinematic dynamo models than artificial flux
  deposition. We demonstrate how this technique can be used to assimilate
  active region observations from US National Solar Observatory/Kitt Peak
  (NSO/KP) synoptic magnetograms, and how our model couples naturally
  with three-dimensional simulations of the Sun's coronal magnetic
  field. This paves the way for the simultaneous study of the evolution
  of the magnetic field in the solar interior as well as its impact on
  the heliosphere.

---------------------------------------------------------
Title: Helioseismic Perspective of the Solar Dynamo
Authors: Muñoz-Jaramillo, A.; Martens, P. C. H.; Nandy, D.
2013ASPC..478..271M    Altcode:
  Helioseismology has been, without a doubt, one of the greatest
  contributors to our understanding of the solar cycle. In particular,
  its results have been critical in the development of solar dynamo
  models, by providing modelers with detailed information about the
  internal, large scale flows of solar plasma. <P />This review will
  give a historical overview of the evolution of our understanding of the
  solar cycle, placing special emphasis on advances driven by helioseismic
  results. We will discuss some of the outstanding modeling issues, and
  discuss how Helioseismology can help push our understanding forward
  during the next decade.

---------------------------------------------------------
Title: Kinematic active region formation in a three-dimensional
    solar dynamo model
Authors: Yeates, A. R.; Muñoz-Jaramillo, A.
2013MNRAS.436.3366Y    Altcode: 2013arXiv1309.6342Y; 2013MNRAS.tmp.2495Y
  We propose a phenomenological technique for modelling the emergence
  of active regions within a three-dimensional, kinematic dynamo
  framework. By imposing localized velocity perturbations, we create
  emergent flux tubes out of toroidal magnetic field at the base of
  the convection zone, leading to the eruption of active regions at the
  solar surface. The velocity perturbations are calibrated to reproduce
  observed active region properties (including the size and flux of active
  regions, and the distribution of tilt angle with latitude), resulting
  in a more consistent treatment of flux-tube emergence in kinematic
  dynamo models than artificial flux deposition. We demonstrate how this
  technique can be used to assimilate observations and drive a kinematic
  three-dimensional model, and use it to study the characteristics of
  active region emergence and decay as a source of poloidal field. We
  find that the poloidal components are strongest not at the solar
  surface, but in the middle convection zone, in contrast with the
  common assumption that the poloidal source is located near the solar
  surface. We also find that, while most of the energy is contained in
  the lower convection zone, there is a good correlation between the
  evolution of the surface and interior magnetic fields.

---------------------------------------------------------
Title: Using the Dipolar and Quadrupolar Moments to Improve
    Solar-Cycle Predictions Based on the Polar Magnetic Fields
Authors: Muñoz-Jaramillo, Andrés; Balmaceda, Laura A.; DeLuca,
   Edward E.
2013PhRvL.111d1106M    Altcode: 2013arXiv1308.2038M
  The solar cycle and its associated magnetic activity are the main
  drivers behind changes in the interplanetary environment and Earth’s
  upper atmosphere (commonly referred to as space weather and climate). In
  recent years there has been an effort to develop accurate solar cycle
  predictions, leading to nearly a hundred widely spread predictions for
  the amplitude of solar cycle 24. Here we show that cycle predictions
  can be made more accurate if performed separately for each hemisphere,
  taking advantage of information about both the dipolar and quadrupolar
  moments of the solar magnetic field during minimum.

---------------------------------------------------------
Title: Solar Cycle Propagation, Memory, and Prediction: Insights
    from a Century of Magnetic Proxies
Authors: Munoz-Jaramillo, Andres; Dasi-Espuig, M.; Balmaceda, L. A.;
   DeLuca, E. E.
2013SPD....4440302M    Altcode:
  In the simplest of forms, modern dynamo theory describes the solar cycle
  as a process that takes the solar magnetic field (back and forth) from
  a configuration that is predominantly poloidal (contained inside the
  meridional plane), to one predominantly toroidal (wrapped around the
  axis of rotation). However, there is still uncertainty and controversy
  in the detailed understanding of this process. A major contributor to
  this uncertainty is the lack of direct long-term databases covering
  different components of the solar magnetic field (an issue mainly
  affecting the poloidal component of the solar magnetic field). In
  this talk we will review the different observations that can be used
  as proxies for the solar magnetic field (in absence of direct magnetic
  observations). I will present a recently standardized database that can
  be used as a proxy for the evolution of the polar magnetic field. And
  to conclude, I will show the insights that can be gained (by taking
  advantage of this database) in the context of the transition between
  the toroidal and poloidal phases of the cycle, solar cycle memory
  as determined by the different mechanisms of flux transport, and the
  practical goal of solar cycle prediction.

---------------------------------------------------------
Title: Using the dipolar and quadrupolar moments to improve solar
    cycle predictions based on the polar magnetic fields
Authors: Munoz-Jaramillo, Andres; Balmaceda, L. A.; DeLuca, E. E.
2013SPD....44..129M    Altcode:
  The solar cycle and its associated magnetic activity are the main
  drivers behind changes in the interplanetary environment and the Earth's
  upper atmosphere. These changes have a direct impact on the lifetime of
  space-based assets and can create hazards to astronauts in space. In
  recent years there has been an effort to develop accurate solar cycle
  predictions (with aims at predicting the long-term evolution of space
  weather), leading to nearly a hundred widely spread predictions for
  the amplitude of solar cycle 24. In this presentation we show how cycle
  predictions can be made more accurate if performed separately for each
  hemisphere, taking advantage of information about both the dipolar
  and quadrupolar moments of the solar magnetic field. Additionally,
  by extending the relationship between polar flux at solar minimum
  and the amplitude of the next cycle to encompass a full century, we
  demonstrate the power of predictions based on the solar polar field --
  paving the way for a new generation of better and more accurate solar
  cycle predictions.

---------------------------------------------------------
Title: Solar Cycle Propagation, Memory, and Prediction: Insights
    from a Century of Magnetic Proxies
Authors: Muñoz-Jaramillo, Andrés; Dasi-Espuig, María; Balmaceda,
   Laura A.; DeLuca, Edward E.
2013ApJ...767L..25M    Altcode: 2013arXiv1304.3151M
  The solar cycle and its associated magnetic activity are the main
  drivers behind changes in the interplanetary environment and Earth's
  upper atmosphere (commonly referred to as space weather). These
  changes have a direct impact on the lifetime of space-based assets
  and can create hazards to astronauts in space. In recent years there
  has been an effort to develop accurate solar cycle predictions (with
  aims at predicting the long-term evolution of space weather), leading
  to nearly a hundred widely spread predictions for the amplitude of
  solar cycle 24. A major contributor to the disagreement is the lack
  of direct long-term databases covering different components of the
  solar magnetic field (toroidal versus poloidal). Here, we use sunspot
  area and polar faculae measurements spanning a full century (as our
  toroidal and poloidal field proxies) to study solar cycle propagation,
  memory, and prediction. Our results substantiate predictions based
  on the polar magnetic fields, whereas we find sunspot area to be
  uncorrelated with cycle amplitude unless multiplied by area-weighted
  average tilt. This suggests that the joint assimilation of tilt and
  sunspot area is a better choice (with aims to cycle prediction) than
  sunspot area alone, and adds to the evidence in favor of active region
  emergence and decay as the main mechanism of poloidal field generation
  (i.e., the Babcock-Leighton mechanism). Finally, by looking at the
  correlation between our poloidal and toroidal proxies across multiple
  cycles, we find solar cycle memory to be limited to only one cycle.

---------------------------------------------------------
Title: Use of a time delay dynamo model to obtain solar-like sunspot
    cycles
Authors: Amouzou, E.; Nandy, D.; Muñoz-Jaramillo, A.; Martens, P.
2013ASInC..10...83A    Altcode:
  Using a delay-differential equation model, we simulate the solar
  dynamo. We find that solar-like dynamo solutions exist in certain
  parameter regimes for which the dynamo number is less than or about
  equal to -3 (|N_D| &gt; 3, N_D &lt; 0) and that sunspot cycle periods of
  11 years can be reproduced with the parameter values set at a magnetic
  diffusivity of η = 3.5 × 10^{12} cm^{2}/s and a total time delay of
  approximately 2.8 yr.

---------------------------------------------------------
Title: Understanding the Role of the Polar Fields on the Propagation
    of the Solar Cycle
Authors: Munoz-Jaramillo, A.; DeLuca, E. E.
2012AGUFMSH13C2263M    Altcode:
  In addition to the well known 11-year periodicity, the solar cycle also
  presents long-term modulations of its amplitude and period which play
  a determinant role in the evolution of space weather and climate. To
  this date, the efforts at understanding long-term solar variability
  have focused on the active parts of the cycle using sunspot properties
  as their main source of data. However, the recent extend minimum
  of sunspot cycle 23 has shown us that the quiet parts of the cycle
  are equally important and thus long-term databases complementary to
  sunspot properties are necessary. Here we use a homogeneous database
  of polar magnetic flux measurements going back to the beginning of
  the 20th century to study the role of the polar flux in the long-term
  evolution of the heliospheric magnetic field, as well as the relevance
  of the polar magnetic field for the evolution of the solar cycle. We
  demonstrate that the polar fields are crucial for the evolution of
  both types of magnetic field and how the results presented here lay
  the foundations for a new generation of sunspot cycle predictions.

---------------------------------------------------------
Title: All Quiet on the Solar Front: Origin and Heliospheric
    Consequences of the Unusual Minimum of Solar Cycle 23
Authors: Nandy, D.; Muñoz-Jaramillo, A.; Martens, P. C. H.
2012SunGe...7...17N    Altcode:
  The magnetic activity of the Sun shapes the heliospheric space
  environment through modulation of the solar wind, interplanetary
  magnetic field, cosmic ray flux and solar irradiance. Sunspots -
  strongly magnetized regions on the solar surface - also spawns solar
  storms such as flares and coronal mass ejections which generate severe
  space weather affecting space-based technologies. The Sun's magnetic
  output varies in a cyclic manner going through phases of maximum and
  minimum activity. Following solar cycle 23 the Sun entered a prolonged
  and unusually long minimum with a large number of days without sunspots
  that was unprecedented in the space age. This long phase of very low
  solar activity resulted in record high cosmic ray flux at Earth, weak
  solar wind speeds and low interplanetary magnetic field. We provide an
  overview of this peculiar solar minimum, critically explore theories
  for its origin and argue that the unusual conditions in the heliosphere
  that we experienced during this minimum eventually originated in solar
  internal dynamics.

---------------------------------------------------------
Title: Calibrating 100 Years of Polar Faculae Measurements:
    Implications for the Evolution of the Heliospheric Magnetic Field
Authors: Muñoz-Jaramillo, Andrés; Sheeley, Neil R.; Zhang, Jie;
   DeLuca, Edward E.
2012ApJ...753..146M    Altcode: 2013arXiv1303.0345M
  Although the Sun's polar magnetic fields are thought to provide
  important clues for understanding the 11 year sunspot cycle, including
  the observed variations of its amplitude and period, the current
  database of high-quality polar field measurements spans relatively
  few sunspot cycles. In this paper, we address this deficiency by
  consolidating Mount Wilson Observatory polar faculae data from four
  data reduction campaigns, validating it through a comparison with
  facular data counted automatically from Michelson Doppler Imager (MDI)
  intensitygrams, and calibrating it against polar field measurements
  taken by the Wilcox Solar Observatory and average polar field and
  total polar flux calculated using MDI line-of-sight magnetograms. Our
  results show that the consolidated polar facular measurements are in
  excellent agreement with both polar field and polar flux estimates,
  making them an ideal proxy to study the evolution of the polar
  magnetic field. Additionally, we combine this database with sunspot
  area measurements to study the role of the polar magnetic flux in the
  evolution of the heliospheric magnetic field (HMF). We find that there
  is a strong correlation between HMF and polar flux at solar minimum
  and that, taken together, polar flux and sunspot area are better
  at explaining the evolution of the HMF during the last century than
  sunspot area alone.

---------------------------------------------------------
Title: Use of a Time Delay Dynamo Model to Obtain Sun-Like Sunspot
    Cycles
Authors: Amouzou, Ernest C.; Nandy, D.; Munoz-Jaramillo, A.; Martens,
   P. C. H.
2012AAS...22020611A    Altcode:
  Using a time delay-based, simplified dynamo model, we attempted to
  produce results characteristic of the Sun when the parameters are
  set to solar values. We found that dynamo solutions exist for dynamo
  numbers less than or about equal to -3 (|ND| &gt; 3,ND &lt; 0) and that
  sunspot cycle periods of the same order of magnitude of the 11-year
  sunspot cycle can be obtained when the diffusive time scale and the
  total time delay are both about four years.

---------------------------------------------------------
Title: Calibration Of a Century of Polar Field Measurements and
    what this Tells us About the Long-term Variability of the Solar and
    Heliospheric Magnetic Field
Authors: Munoz-Jaramillo, Andres; Sheeley, N. R.; Zhang, J.; DeLuca,
   E. E.
2012AAS...22012304M    Altcode:
  In addition to the well known 11-year periodicity, the solar cycle also
  presents long-term modulations of its amplitude and period which play
  a determinant role in the evolution of space weather and climate. To
  this date, the efforts at understanding long-term solar variability
  have focused on the active parts of the cycle using sunspot properties
  as their main source of data. However, the recent extend minimum of
  sunspot cycle 23 has shown us that the quiet parts of the cycle are
  equally important and thus long-term databases complementary to sunspot
  properties are necessary. <P />Here we show how to consolidate Mount
  Wilson Observatory polar faculae data from four observational campaigns
  (1906-1964, Sheeley 1966; 1960-1975, Sheeley 1976; 1975-1990, Sheeley
  1991; 1985-2007, Sheeley 2008), validate it through a comparison
  with facular data counted automatically from MDI intensitygrams,
  and calibrate it against polar field measurements taken by the Wilcox
  Solar Observatory (1977-2011) and average polar field and total polar
  flux calculated using MDI line-of-sight magnetograms (1996-2011). <P
  />We also show that the consolidated polar facular measurements are
  in excellent agreement with both polar field and polar flux estimates,
  making them an ideal proxy to study the evolution of the polar magnetic
  field since 1906 and use this proxy to study the role of polar flux in
  the evolution of the solar cycle and the Heliospheric Magnetic Field
  (HMF).

---------------------------------------------------------
Title: The Double-Ring Algorithm: A Tool for Assimilating Active
    Region Data Directly into Kinematic Dynamo Models
Authors: Munoz-Jaramillo, A.; Nandi, D.; Martens, P. C.; Yeates, A. R.
2011AGUFMSH51B2009M    Altcode:
  The emergence of tilted bipolar active regions and the dispersal of
  their flux, mediated via processes such as diffusion, differential
  rotation and meridional circulation is believed to be responsible for
  the reversal of the Sun's polar field. This process (commonly known as
  the Babcock-Leighton mechanism) is usually modeled as a near-surface,
  spatially distributed α-effect in kinematic mean-field dynamo
  models. However, not only this formulation leads to a relationship
  between polar field strength and meridional flow speed which is
  opposite to that suggested by physical insight and predicted by
  surface flux-transport simulations, but also makes it very difficult to
  assimilate active region data into kinematic dynamo models. With this
  in mind, we present an improved double-ring algorithm for modeling the
  Babcock-Leighton mechanism based on active region eruption, within
  the framework of an axisymmetric dynamo model. We demonstrate that
  our treatment of the Babcock-Leighton mechanism through double-ring
  eruption leads to an inverse relationship between polar field strength
  and meridional flow speed as expected, reconciling the discrepancy
  between surface flux-transport simulations and kinematic dynamo
  models. Finally, we show how this new formulation paves the way
  for applications, which were not possible before, like the direct
  assimilation of active region data.

---------------------------------------------------------
Title: Bridging the Gap: Recent Improvements of Kinematic Models of
    the Solar Magnetic Cycle
Authors: Munoz-Jaramillo, A.
2011AGUFMSH34B..06M    Altcode:
  Kinematic dynamo models are the tool par excellence for understanding
  the solar magnetic cycle. During the last decade, this type of
  models has seen a continuous evolution and has become increasingly
  successful at reproducing solar cycle characteristics. Unfortunately,
  most of ingredients that make up a kinematic dynamo model remain poorly
  constrained allowing one to obtain solar-like solutions by "tuning"
  the input parameters - leading to controversy regarding which parameter
  set is more appropriate. In this talk we will revisit two of those
  ingredients and show how to constrain them better by using theoretical
  considerations. For the turbulent magnetic diffusivity - an ingredient
  which attempts to capture the effect of convective turbulence on the
  large scale magnetic field - we show that combining mixing-length
  theory estimates with magnetic quenching allows us to obtain viable
  magnetic cycles (otherwise impossible) and that the commonly used
  diffusivity profiles can be understood as a spatiotemporal average of
  this process. For the poloidal source - the ingredient which closes
  the cycle by regenerating the poloidal magnetic field - we introduce
  a more realistic way of modeling active region emergence and decay
  and find that this resolves existing discrepancies between kinematic
  dynamo models and surface flux transport simulations. This formulation
  has made possible to study the physical mechanisms leading to the
  extended minimum of cycle 23 and paves the way for future coupling
  between kinematic dynamos and models of the solar corona.

---------------------------------------------------------
Title: Recent Improvements of Kinematic Models of the Solar Magnetic
    Cycle
Authors: Muñoz-Jaramillo, Andrés; Nandy, Dibyendu; Martens, Petrus
   C. H.
2011shin.confE...3M    Altcode:
  One of the best tools we have for understanding the origin of
  solar magnetic variability are kinematic dynamo models. During the
  last decade, this type of models has seen a continuous evolution
  and has become increasingly successful at reproducing solar cycle
  characteristics. Unfortunately, most of ingredients that make up
  a kinematic dynamo model remain poorly constrained allowing one to
  obtain solar-like solutions by 'tuning' the input parameters' leading
  to controversy regarding which parameter set is more appropriate. In
  this poster we will revisit two of those ingredients and show how to
  constrain them better by using observational data and theoretical
  considerations. <P />For the turbulent magnetic diffusivity -
  an ingredient which attempts to capture the effect of convective
  turbulence on the large scale magnetic field - we show that combining
  mixing-length theory estimates with magnetic quenching allows us
  to obtain viable magnetic cycles (otherwise impossible) and that the
  commonly used diffusivity profiles can be understood as a spatiotemporal
  average of this process. <P />For the poloidal source - the ingredient
  which closes the cycle by regenerating the poloidal magnetic field -
  we introduce a more realistic way of modeling active region emergence
  and decay and find that this resolves existing discrepancies between
  kinematic dynamo models and surface flux transport simulations. This
  formulation has made possible to study the physical mechanisms leading
  to the extended minimum of cycle 23 and paves the way for future
  coupling between kinematic dynamos and models of the solar corona. <P
  />This work is funded by NASA Living With a Star Grant NNX08AW53G to
  Montana State University/Harvard-Smithsonian Center for Astrophysics
  and the Government of India's Ramanujan Fellowship.

---------------------------------------------------------
Title: The Unusual Minimum of Solar Cycle 23: Origin and Heliospheric
    Consequences
Authors: Nandi, Dibyendu; Munoz-Jaramillo, Andres; Martens, Piet C. H.
2011simi.conf....5N    Altcode:
  Solar cycle 23 was characterized by very weak polar magnetic field and
  a large number of sunspot-less unprecedented in almost a century. This
  resulted in atypical conditions in our space environment, including
  low solar radiative flux, weak solar wind and heliospheric magnetic
  field and record-high cosmic rays flux. Here I will review some of
  these unusual conditions in space during the recently concluded solar
  minimum and present the first consistent explanation of this deep
  solar minimum based on dynamo simulations.

---------------------------------------------------------
Title: Meridional Surface Flows and the Recent Extended Solar Minimum
Authors: Martens, Petrus C.; Nandy, D.; Munoz-Jaramillo, A.
2011SPD....42.1705M    Altcode: 2011BAAS..43S.1705M
  Nandy, Munoz, &amp; Martens, have published a kinematic dynamo model
  that successfully reproduces the main characteristics of the recent
  extended solar minimum (Nature 2011, 471, 80). The model depends on
  the solar meridional flow and its return flow along the tachocline
  determining the period and character of the cycle. In particular Nandy
  et al. found that a meridional flow that is fast in the first half
  of the cycle and then slows down around solar maximum, can lead to
  an extended minimum with the characteristics of the recent minimum:
  an extended period without sunspots and weak polar fields. <P />It has
  been pointed out that the observed surface meridional flows over the
  last cycle do not fit the pattern assumed by Nandy et al. Hathaway &amp;
  Rightmire (Science 2010, 327-1350) find that the meridional speed of
  small magnetic surface elements observed by SoHO/MDI decreased around
  solar maximum and has not yet recovered. Basu &amp; Antia (ApJ 2010,
  717, 488) find surface plasma meridional flow speeds that are lower at
  solar maximum 23 than at the surrounding minima, which is different
  from both Hathaway and Nandy. <P />While there is no physical reason
  that solar surface flows -- both differential rotation and meridional
  flow -- would vary in lockstep with flows at greater depth, as the
  large radial gradients near the surface clearly indicate, and while
  Nandy et al. have demonstrated that the deeper flows dominate the net
  meridional mass flow, we find that there is in effect a very satisfying
  agreement between the observational results of Hathaway &amp; Rightmire,
  Basu &amp; Antia, and the model assumptions of Nandy, Munoz, &amp;
  Martens. We present an analytical model that reconciles the first two,
  followed by a hydrodynamical model that demonstrates the consistency of
  these observational results with the model assumptions of Nandy et al.

---------------------------------------------------------
Title: Understanding the Origin of the Extended Minimum of Sunspot
    Cycle 23
Authors: Munoz-Jaramillo, Andres; Nandy, D.; Martens, P. C. H.
2011SPD....42.1743M    Altcode: 2011BAAS..43S.1743M
  The minimum of solar cycle 23 was characterized by very weak polar
  field strength and a large number of sunspot-less days that was
  unprecedented in the space age. This has had significant consequences in
  the heliospheric space environment in terms of record-high cosmic-ray
  flux and low levels of solar irradiance - which is the primary natural
  driver of the climate system. During this un-anticipated phase,
  there was some speculation as to whether the solar minimum could lead
  to a Maunder-like grand minimum which coincided with the Little Ice
  Age. Here we present the first consistent explanation of the defining
  characteristics of this unusual minimum based on variations in the
  solar meridional plasma flows, and discuss how our results compare with
  observations. <P />This work is funded by NASA Living With a Star Grant
  NNX08AW53G to Montana State University/Harvard-Smithsonian Center for
  Astrophysics and the Government of India's Ramanujan Fellowship.

---------------------------------------------------------
Title: The Double-Ring Algorithm: Reconciling Surface Flux Transport
    Simulations and Kinematic Dynamo Models
Authors: Munoz-Jaramillo, Andres; Nandy, D.; Martens, P. C. H.;
   Yeates, A. R.
2011SPD....42.0205M    Altcode: 2011BAAS..43S.0205M
  The emergence of tilted bipolar active regions and the dispersal of
  their flux, mediated via processes such as diffusion, differential
  rotation and meridional circulation is believed to be responsible
  for the reversal of the Sun's polar field. This process (commonly
  known as the Babcock-Leighton mechanism) is usually modeled as a
  near-surface, spatially distributed α-effect in kinematic mean-field
  dynamo models. However, this formulation leads to a relationship
  between polar field strength and meridional flow speed which is
  opposite to that suggested by physical insight and predicted by
  surface flux-transport simulations. With this in mind, we present
  an improved double-ring algorithm for modeling the Babcock-Leighton
  mechanism based on active region eruption, within the framework of
  an axisymmetric dynamo model. We demonstrate that our treatment of
  the Babcock-Leighton mechanism through double-ring eruption leads to
  an inverse relationship between polar field strength and meridional
  flow speed as expected, reconciling the discrepancy between surface
  flux-transport simulations and kinematic dynamo models. Finally,
  we show how this new formulation paves the way for applications,
  which were not possible before, like understanding the nature of the
  extended minimum of sunspot cycle 23 and direct assimilation of active
  region data. <P />This work is funded by NASA Living With a Star Grant
  NNX08AW53G to Montana State University/Harvard-Smithsonian Center for
  Astrophysics and the Government of India's Ramanujan Fellowship.

---------------------------------------------------------
Title: The unusual minimum of sunspot cycle 23 caused by meridional
    plasma flow variations
Authors: Nandy, Dibyendu; Muñoz-Jaramillo, Andrés; Martens, Petrus
   C. H.
2011Natur.471...80N    Altcode: 2013arXiv1303.0349N
  Direct observations over the past four centuries show that the number
  of sunspots observed on the Sun's surface varies periodically, going
  through successive maxima and minima. Following sunspot cycle 23,
  the Sun went into a prolonged minimum characterized by a very weak
  polar magnetic field and an unusually large number of days without
  sunspots. Sunspots are strongly magnetized regions generated by a
  dynamo mechanism that recreates the solar polar field mediated through
  plasma flows. Here we report results from kinematic dynamo simulations
  which demonstrate that a fast meridional flow in the first half of a
  cycle, followed by a slower flow in the second half, reproduces both
  characteristics of the minimum of sunspot cycle 23. Our model predicts
  that, in general, very deep minima are associated with weak polar
  fields. Sunspots govern the solar radiative energy and radio flux,
  and, in conjunction with the polar field, modulate the solar wind, the
  heliospheric open flux and, consequently, the cosmic ray flux at Earth.

---------------------------------------------------------
Title: Magnetic Quenching of Turbulent Diffusivity: Reconciling
    Mixing-length Theory Estimates with Kinematic Dynamo Models of the
    Solar Cycle
Authors: Muñoz-Jaramillo, Andrés; Nandy, Dibyendu; Martens, Petrus
   C. H.
2011ApJ...727L..23M    Altcode: 2010arXiv1007.1262M
  The turbulent magnetic diffusivity in the solar convection zone is
  one of the most poorly constrained ingredients of mean-field dynamo
  models. This lack of constraint has previously led to controversy
  regarding the most appropriate set of parameters, as different
  assumptions on the value of turbulent diffusivity lead to radically
  different solar cycle predictions. Typically, the dynamo community
  uses double-step diffusivity profiles characterized by low values of
  diffusivity in the bulk of the convection zone. However, these low
  diffusivity values are not consistent with theoretical estimates based
  on mixing-length theory, which suggest much higher values for turbulent
  diffusivity. To make matters worse, kinematic dynamo simulations cannot
  yield sustainable magnetic cycles using these theoretical estimates. In
  this work, we show that magnetic cycles become viable if we combine the
  theoretically estimated diffusivity profile with magnetic quenching of
  the diffusivity. Furthermore, we find that the main features of this
  solution can be reproduced by a dynamo simulation using a prescribed
  (kinematic) diffusivity profile that is based on the spatiotemporal
  geometric average of the dynamically quenched diffusivity. This bridges
  the gap between dynamically quenched and kinematic dynamo models,
  supporting their usage as viable tools for understanding the solar
  magnetic cycle.

---------------------------------------------------------
Title: Towards better constrained models of the solar magnetic cycle
Authors: Munoz-Jaramillo, Andres
2010PhDT.......193M    Altcode:
  The best tools we have for understanding the origin of solar magnetic
  variability are kinematic dynamo models. During the last decade,
  this type of models has seen a continuous evolution and has become
  increasingly successful at reproducing solar cycle characteristics. The
  basic ingredients of these models are: the solar differential rotation
  -- which acts as the main source of energy for the system by shearing
  the magnetic field; the meridional circulation -- which plays a crucial
  role in magnetic field transport; the turbulent diffusivity -- which
  attempts to capture the effect of convective turbulence on the large
  scale magnetic field; and the poloidal field source -- which closes
  the cycle by regenerating the poloidal magnetic field. However, most
  of these ingredients remain poorly constrained which allows one to
  obtain solar-like solutions by "tuning" the input parameters, leading
  to controversy regarding which parameter set is more appropriate. In
  this thesis we revisit each of those ingredients in an attempt to
  constrain them better by using observational data and theoretical
  considerations, reducing the amount of free parameters in the model. For
  the meridional flow and differential rotation we use helioseismic data
  to constrain free parameters and find that the differential rotation
  is well determined, but the available data can only constrain the
  latitudinal dependence of the meridional flow. For the turbulent
  magnetic diffusivity we show that combining mixing-length theory
  estimates with magnetic quenching allows us to obtain viable magnetic
  cycles and that the commonly used diffusivity profiles can be understood
  as a spatiotemporal average of this process. For the poloidal source
  we introduce a more realistic way of modeling active region emergence
  and decay and find that this resolves existing discrepancies between
  kinematic dynamo models and surface flux transport simulations. We also
  study the physical mechanisms behind the unusually long minimum of cycle
  23 and find it to be tied to changes in the meridional flow. Finally,
  by carefully constraining the system through surface magnetic field
  observations, we find that what is believed to be the primary source
  of poloidal field (also known as Babckock-Leigthon mechanism) may not
  be enough to sustain the solar magnetic cycle.

---------------------------------------------------------
Title: A Double-ring Algorithm for Modeling Solar Active Regions:
    Unifying Kinematic Dynamo Models and Surface Flux-transport
    Simulations
Authors: Muñoz-Jaramillo, Andrés; Nandy, Dibyendu; Martens, Petrus
   C. H.; Yeates, Anthony R.
2010ApJ...720L..20M    Altcode: 2010arXiv1006.4346M
  The emergence of tilted bipolar active regions (ARs) and the dispersal
  of their flux, mediated via processes such as diffusion, differential
  rotation, and meridional circulation, is believed to be responsible
  for the reversal of the Sun's polar field. This process (commonly
  known as the Babcock-Leighton mechanism) is usually modeled as a
  near-surface, spatially distributed α-effect in kinematic mean-field
  dynamo models. However, this formulation leads to a relationship
  between polar field strength and meridional flow speed which is
  opposite to that suggested by physical insight and predicted by surface
  flux-transport simulations. With this in mind, we present an improved
  double-ring algorithm for modeling the Babcock-Leighton mechanism
  based on AR eruption, within the framework of an axisymmetric dynamo
  model. Using surface flux-transport simulations, we first show that an
  axisymmetric formulation—which is usually invoked in kinematic dynamo
  models—can reasonably approximate the surface flux dynamics. Finally,
  we demonstrate that our treatment of the Babcock-Leighton mechanism
  through double-ring eruption leads to an inverse relationship between
  polar field strength and meridional flow speed as expected, reconciling
  the discrepancy between surface flux-transport simulations and kinematic
  dynamo models.

---------------------------------------------------------
Title: Towards better Constrained Kinematic Dynamo Models: Turbulent
    Diffusivity and Diffusivity Quenching
Authors: Munoz-Jaramillo, Andres; Nandy, D.; Martens, P. C. H.
2010AAS...21640116M    Altcode:
  The turbulent magnetic diffusivity in the Solar Convection Zone
  (SCZ) is one of the most poorly constrained ingredients of mean-field
  dynamo models. This lack of constrain has previously led to controversy
  regarding which set of parameters is more appropriate (yielding better
  solar like solutions) and the generation of radically different cycle
  predictions. Furthermore, due to the relative freedom in the different
  parameters associated with it, more often than not it is used to finely
  tune the dynamo solutions. As of now, the dynamo community seems
  to have settled on double step diffusivity profiles characterized
  by low values of diffusivity inside most of the convection zone;
  notwithstanding that these values of diffusivity are not consistent
  with theoretical considerations based on mixing-length theory, which
  suggest much higher values of turbulent diffusivity. To make matters
  worse, standard kinematic dynamo simulations cannot yield sustainable
  magnetic cycles using theoretical estimates. Here we study how magnetic
  diffusivity quenching can provide a physically meaningful way out of
  this discrepancy and whether standard diffusivity profiles are truly
  a representation of a physical process. This work is funded by NASA
  Living With a Star grant NNG05GE47G.

---------------------------------------------------------
Title: Are Active Regions as Relevant for the Solar Cycle as we Think?
Authors: Munoz-Jaramillo, Andres; Nandy, D.; Martens, P. C. H.
2010AAS...21640108M    Altcode: 2010BAAS...41R.858M
  The long and short term variability of the Sun is strongly determined
  by the evolution of the solar magnetic cycle, which is sustained
  through the action of a magneto-hydrodynamic dynamo. In our current
  understanding of the dynamo, the poloidal field (which acts as a
  starting point for the cycle) is recreated through the emergence and
  decay of active regions subjected to the collective effect of meridional
  circulation and turbulent diffusion; a process commonly referred to as
  the Babcock-Leighton mechanism. Dynamo models based on this mechanism
  have been quite successful in reproducing the different properties of
  the solar cycle and have also been used to make predictions of cycle
  24. However, the question of whether the BL mechanism is enough to
  sustain the solar cycle has not yet been addressed quantitatively. By
  including real active region data in our state of the art kinematic
  dynamo model we are able to take the first steps into answering this
  question. <P />This work is funded by NASA Living With a Star grant
  NNG05GE47G.

---------------------------------------------------------
Title: The Unusual Minimum of Solar Cycle 23 Explained
Authors: Nandy, Dibyendu; Munoz-Jaramillo, A.; Martens, P. C. H.
2010AAS...21631703N    Altcode: 2010BAAS...41..898N
  The minimum in activity between solar cycle 23 and 24 has been the
  deepest in the space age, with an unusually large number of days
  without sunspots and weak solar dipolar field strength. This has
  had consequences for the heliosphere and planetary atmospheres -
  given the weak solar wind, low solar irradiance and radio flux and
  historically high values of cosmic ray flux that has characterized
  this minimum epoch. The origin of this peculiar minimum has not
  yet been clearly understood. Here we present the first theoretical
  explanation of this deep minimum based on simulations of the solar
  dynamo mechanism - which seeks to explain the origin and variability
  of solar magnetic fields. Our simulations have uncovered a somewhat
  surprising explanation, which however, provides a consistent solution
  to both of the unusual features of this minimum; namely, the long period
  when sunspots were missing and the very weak solar polar field strength.

---------------------------------------------------------
Title: Towards better constrained models of the solar magnetic cycle
Authors: Muñoz-Jaramillo, Andrés
2010PhDT.......452M    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: What do Solar Kinematic Models Tell us About the Current
    Minimum?
Authors: Muñoz-Jaramillo, A.; Nandy, D.; Martens, P. C.
2009AGUFMSH11A1505M    Altcode:
  In the last three years the sun has reached the most unusual minimum
  in the space age. Although minima as long as this one have happened
  several times in the past, this one has come as a surprise in contrast
  with the previous four who where fairly regular. However, such an event
  is a perfect opportunity to learn more about the solar cycle and the
  processes that drive it. In order to understand this event we turn
  to kinematic dynamo models, which are the best tool we currently have
  for understanding the solar cycle. Although modelers have been aware
  of the role of the different components into setting the period of the
  solar cycle, little work has been done in understanding the nature of
  solar minima. Can kinematic models reproduce such an event with all
  it's signatures? In this study we attempt to address this question
  using our state of the art kinematic dynamo model.

---------------------------------------------------------
Title: ERRATUM: "Helioseismic Data Inclusion in Solar Dynamo Models"
    <A href="bib_query\?2009ApJ...698..461M">(2009, ApJ, 698, 461)</A>
Authors: Muñoz-Jaramillo, Andrés; Nandy, Dibyendu; Martens, Petrus
   C. H.
2009ApJ...707.1852M    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Helioseismic Data Inclusion in Solar Dynamo Models
Authors: Muñoz-Jaramillo, Andrés; Nandy, Dibyendu; Martens, Petrus
   C. H.
2009ApJ...698..461M    Altcode: 2008arXiv0811.3441M
  An essential ingredient in kinematic dynamo models of the solar cycle
  is the internal velocity field within the simulation domain—the
  solar convection zone (SCZ). In the last decade or so, the field of
  helioseismology has revolutionized our understanding of this velocity
  field. In particular, the internal differential rotation of the Sun
  is now fairly well constrained by helioseismic observations almost
  throughout the SCZ. Helioseismology also gives us some information
  about the depth dependence of the meridional circulation in the
  near-surface layers of the Sun. The typical velocity inputs used in
  solar dynamo models, however, continue to be an analytic fit to the
  observed differential rotation profile and a theoretically constructed
  meridional circulation profile that is made to match the flow speed
  only at the solar surface. Here, we take the first steps toward
  the use of more accurate velocity fields in solar dynamo models by
  presenting methodologies for constructing differential rotation and
  meridional circulation profiles that more closely conform to the best
  observational constraints currently available. We also present kinematic
  dynamo simulations driven by direct helioseismic measurements for
  the rotation and four plausible profiles for the internal meridional
  circulation—all of which are made to match the helioseismically
  inferred near-surface depth dependence, but whose magnitudes are made to
  vary. We discuss how the results from these dynamo simulations compare
  with those that are driven by purely analytic fits to the velocity
  field. Our results and analysis indicate that the latitudinal shear in
  the rotation in the bulk of the SCZ plays a more important role, than
  either the tachocline or surface radial shear, in the induction of the
  toroidal field. We also find that it is the speed of the equatorward
  counterflow in the meridional circulation right at the base of the
  SCZ, and not how far into the radiative interior it penetrates, that
  primarily determines the dynamo cycle period. Improved helioseismic
  constraints are expected to be available from future space missions
  such as the Solar Dynamics Observatory and through analysis of more
  long-term continuous data sets from ground-based instruments such as
  the Global Oscillation Network Group. Our analysis lays the basis for
  the assimilation of these helioseismic data within dynamo models to
  make future solar cycle simulations more realistic.

---------------------------------------------------------
Title: The Unusual Minimum of Cycle 23: Observations and
    Interpretation
Authors: Martens, Petrus C.; Nandy, D.; Munoz-Jaramillo, A.
2009SPD....40.2403M    Altcode:
  The current minimum of cycle 23 is unusual in its long duration, the
  very low level to which Total Solar Irradiance (TSI) has fallen, and
  the small flux of the open polar fields. The deep minimum of TSI seems
  to be related to an unprecedented dearth of polar faculae, and hence to
  the small amount of open flux. Based upon surface flux transport models
  it has been suggested that the causes of these phenomena may be an
  unusually vigorous meridional flow, or even a deviation from Joy's law
  resulting in smaller Joy angles than usual for emerging flux in cycle
  23. There is also the possibility of a connection with the recently
  inferred emergence in polar regions of bipoles that systematically
  defy Hale's law. <P />Much speculation has been going on as to the
  consequences of this exceptional minimum: are we entering another global
  minimum, is this the end of the 80 year period of exceptionally high
  solar activity, or is this just a statistical hiccup? Dynamo simulations
  are underway that may help answer this question. As an aside it must
  be mentioned that the current minimum of TSI puts an upper limit in the
  TSI input for global climate simulations during the Maunder minimum, and
  that a possible decrease in future solar activity will result in a very
  small but not insignificant reduction in the pace of global warming.

---------------------------------------------------------
Title: Towards Better Constrained Solar Dynamo Models: The Velocity
    Field And Turbulent Diffusivity Profiles
Authors: Munoz-Jaramillo, Andres; Nandy, D.; Martens, P. C. H.
2009SPD....40.0405M    Altcode:
  The best tool we have for understanding the origin of solar
  magnetic variability is the kinematic dynamo model. During the
  last decade this type of models have seen a continuous evolution
  and have become increasingly successful at reproducing solar cycle
  characteristics. However, some of the key ingredients used in dynamo
  models remain poorly constrained which allows one to obtain solar-like
  solutions by "tuning" the input parameters. Here we present out
  efforts to better constrain two of the most important ingredients of
  solar dynamo models:: The internal velocity field (meridional flow and
  differential rotation) and the turbulent diffusivity. To accomplish
  this goal, we formulate techniques to assimilate the latest results
  from helioseismology to constrain the velocity fields. We also apply
  mixing length theory to the Solar Model S, in conjunction with magnetic
  quenching of the turbulent diffusivity, to generate more realistic
  effective turbulent diffusivity profiles for kinematic dynamo models. In
  essence therefore, we try to address some of these outstanding issues in
  a first-principle physics based approach, rather than an ad-hoc manner.

---------------------------------------------------------
Title: Effect of the Magnetic Quenching of the Turbulent Diffusivity
    in a Mean-Field Kinematic Solar Dynamo
Authors: Muñoz-Jaramillo, A.; Nandy, D.; Martens, P. C.
2008AGUSMSP41A..09M    Altcode:
  The fundamental model used to study the solar dynamo mechanism is
  based on the electromagnetic induction equation coupled with Ohm's
  law. Apart from mean-field or other phenomenological source terms
  (such as a Babcock-Leighton alpha-effect), the resultant dynamo
  equation is composed of two terms: An advection and a diffusion
  term. Depending on the relative importance of these two terms, the
  dynamo can operate either in an advection-dominated or a diffusion
  dominated regime. One of the parameters that determine which of these
  regimes the dynamo operates in is the effective magnetic diffusivity,
  this parameter is expected to be enhanced by convective turbulence
  in stellar convection zones. The diffusivity values can range from
  104 cm2/s in the radiative zone (where there is no turbulence) to
  1012-14 cm2/s in the upper convection zone. The depth dependence of
  this effective diffusivity is not particularly well-constrained and
  most commonly used profiles involve a relatively low diffusivity in
  the convection zone (1010-11 cm2/s) - which makes the dynamo operate
  in the advection-dominated regime. The underlying problem here is
  that these values of diffusivity are not consistent with theoretical
  considerations based on mixing-length theory, which suggest much higher
  values of turbulent diffusivity; this would make the dynamo operate
  in a diffusion-dominated regime. However, a possible solution to this
  inconsistency may be in the quenching effect that strong magnetic
  fields have on turbulence. We have recently developed a kinematic solar
  dynamo based on a novel numerical technique called the exponential-
  propagation method. Using this model, we study magnetic diffusivity
  quenching and discuss how its effect may reconcile the theoretically
  suggested turbulent diffusivity values with the effective diffusivity
  profiles most commonly used in this type of models.