Author name code: munoz-jaramillo ADS astronomy entries on 2022-09-14 author:Munoz-Jaramillo, Andres ------------------------------------------------------------------------ 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. Bibcode: 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. 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. Bibcode: 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. 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 Bibcode: 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. Title: Efficient labelling of solar flux evolution videos by a deep learning model Authors: Chatterjee, Subhamoy; Muñoz-Jaramillo, Andrés; Lamb, Derek A. Bibcode: 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. 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. Bibcode: 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. 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 Bibcode: 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. 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. Bibcode: 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.

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.

(2 data files). 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 Bibcode: 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. 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 Bibcode: 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. 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 Bibcode: 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. Title: Leveraging a Deep Neural Network to Efficiently Label Solar Flux Emergence Videos Authors: Chatterjee, Subhamoy; Munoz-Jaramillo, Andres; Lamb, Derek Bibcode: 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. 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 Bibcode: 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. 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 Bibcode: 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. 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. Bibcode: 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. Title: Solar Anti-Hale Bipolar Magnetic Regions: A Distinct Population with Systematic Properties Authors: Muñoz-Jaramillo, Andrés; Navarrete, Benjamín; Campusano, Luis E. Bibcode: 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. 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. Bibcode: 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. Title: Leveraging a Deep Neural Network to Efficiently Label Solar Flux Emergence Videos Authors: Chatterjee, S.; Munoz-Jaramillo, A.; Lamb, D. Bibcode: 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. 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. Bibcode: 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.

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.

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.

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. Title: Investigating the Polar Flux Budget with the Advective Flux Transport Model Authors: Upton, L.; Munoz-Jaramillo, A. Bibcode: 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. 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 Bibcode: 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. Title: The Language of Stars Authors: Berea, A.; Munoz-Jaramillo, A. Bibcode: 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.

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:

1. Can we use NLP to discover features in time series? if yes, how good is it comparatively to other methods, such as clustering?

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?

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 & 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.

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:

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;

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;

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;

1.4. PD clustering-based — this method is based on measurements of entropy and complexity in the time series;

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;

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.

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.

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.

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 Bibcode: 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. Bibcode: 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.

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.

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.

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. Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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).

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.

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.

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. Bibcode: 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. Bibcode: 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 Bibcode: 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 \& 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 Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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).

(4 data files). Title: A Detailed Reconstruction of Solar Activity During the Maunder Minimum Authors: Munoz-Jaramillo, A.; Sanchez-Carrasco, V.; Vaquero, J. M. Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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) 1021Mx (1022Mx). 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. Bibcode: 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 Bibcode: 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. Bibcode: 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)-1*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. Bibcode: 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 Bibcode: 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. Bibcode: 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.

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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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| > 3, N_D < 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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| > 3,ND < 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. Bibcode: 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.

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).

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. Bibcode: 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. Bibcode: 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. Bibcode: 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.

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.

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. Bibcode: 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. Bibcode: 2011SPD....42.1705M Altcode: 2011BAAS..43S.1705M Nandy, Munoz, & 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.

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 & 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 & 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.

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 & Rightmire, Basu & Antia, and the model assumptions of Nandy, Munoz, & 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. Bibcode: 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.

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. Bibcode: 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.

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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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.

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. Bibcode: 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 Bibcode: 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. Bibcode: 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" (2009, ApJ, 698, 461) Authors: Muñoz-Jaramillo, Andrés; Nandy, Dibyendu; Martens, Petrus C. H. Bibcode: 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. Bibcode: 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. Bibcode: 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.

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. Bibcode: 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. Bibcode: 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.