UMBC Goddard Planetary Heliophysics Institute (GPHI)

Permanent URI for this collectionhttp://hdl.handle.net/11603/10907

In May 2011, the NASA Goddard Space Flight Center (GSFC) awarded a Cooperative Agreement to the University of Maryland, Baltimore County, to create a science center for collaborative research in Solar-Planetary Sciences at NASA’s Goddard Space Flight Center, Greenbelt, MD. Through this arrangement, UMBC and its partners – University of Maryland College Park and American University – developed collaborative research programs in all areas of the Heliophysics sciences. This consortium between government and universities to create GPHI (Goddard Planetary Heliophysics Institute) not only provided a secure “home” for Heliophysics scientists, but also synergistically fostered new directions in research and technology.

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Field Aligned Currents and Aurora During the Terrestrial Alfven Wing State
(2025-03-04) Burkholder, Brandon; Chen, Li-Jen; Sorathia, Kareem; Lin, Dong; Vines, Sarah; Bowers, Charles F.
When sub-Alfvenic (Alfven Mach number M_A < 1) plasmas impact Earth, the magnetosphere develops Alfven wings. A Multiscale Atmosphere Geospace Environment (MAGE) global simulation of the April 2023 geomagnetic storm, validated against Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE), reveals the mechanism of field-aligned current (FAC) generation and auroral precipitation for the terrestrial Alfven wings. Simulation and observations show northern hemisphere planetward flowing auroral electrons (negative FAC) are predominantly at magnetic local times (MLTs) 5-11. Just before the wings formed, solar wind conditions were similar and 1 < M_A < 2, yet negative FAC extended across the entire day-side and night-side dusk sectors. Flow vorticity drives FACs at the boundary of the Alfven wings and unshocked solar wind. The Alfven wing shape presents a different obstacle to the solar wind compared to typical lobe fluxes, producing the unique FAC and auroral patterns. New insights about Alfven wing FACs will generate new understanding of aurora for exoplanets inside their host star's Alfven zone.
Mach Number Scaling of Foreshock Magnetic Fluctuations at Quasi-parallel Bow Shocks and Their Role in Magnetospheric Driving Throughout the Solar System
(AAS, 2025-01-30) Burkholder, Brandon; Chen, Li-Jen; Nykyri, Katariina; Romanelli, Norberto; Sarantos, Menelaos; Sibeck, Dave; Verniero, Jaye; DiBraccio, Gina A.; Gershman, Daniel; Lindberg, Martin; Kincade, Erin
Upstream of quasi-parallel bow shocks, reflected ions generate ion–ion instabilities. The resulting magnetic fluctuations can advect through the shock and interact with planetary magnetospheres. The amplitude of magnetic fluctuations depends on the strength of the shock, quantified by the Alfvén Mach number (MA), which is the ratio of solar wind velocity to the local Alfvén velocity. With increasing heliocentric distance, the solar wind MA generally increases, such that Mercury typically experiences a lower MA ~ 5 compared to Earth (MA ~ 8), and Mars a slightly higher MA ~ 9. Farther out in the solar system, Saturn has even higher MA (~10). However, the solar wind flow is highly irregular, and on top of solar cycle variations these values for average MA at each planet do not capture extreme events. Statistical analysis of OMNIWeb observations from 2015 to 2023 shows that sustained (30 minutes or more) high MA (30–100) occurs at Earth about once a month. Using a selection of events in the ion foreshock regions of Mercury, Earth, Mars, and Saturn, a linear scaling is calculated for the maximum magnetic fluctuation amplitude as a function of MA. The resulting slope is ~0.2. Based on the dominant fluctuation frequency for the largest-amplitude events at each planet, it is found that Mars exists in a special regime where the wave period of the magnetic fluctuations can be similar to or longer than the magnetospheric convection timescale, making Mars more susceptible to space weather effects associated with foreshock fluctuations.
Radial Evolution of Interplanetary Shock Properties with Heliospheric Distance: Observations from Parker Solar Probe
(AAS, 2025-01-14) Kruparova, Oksana; Szabo, Adam; Jian, Lan K.; Němec, František; Šafránková, Jana; Němeček, Zdeněk ; Pasanen, Jacob; Narock, Ayris; Krupar, Vratislav
We present a comprehensive analysis of 66 interplanetary shocks observed by the Parker Solar Probe between 2018 November and 2024 January. Among these, 33 events fulfilled the Rankine–Hugoniot (R-H) conditions, ensuring reliable asymptotic plasma parameter solutions. The remaining 33 events could not be confirmed by the standard R-H approach—potentially including wave-like structures—yet were analyzed via averaging and mixed-data methods to obtain robust shock parameters. Utilizing our ShOck Detection Algorithm database, the shocks are categorized into fast-forward, fast-reverse, slow-forward, and slow-reverse types. We investigate the statistical properties of these shocks, focusing on correlations between key parameters—magnetic field compression, density compression, shock normal angle, and change in velocity—and heliocentric distance. Significant positive correlations are identified between heliocentric distance and both magnetic field compression and density compression, suggesting that shocks strengthen as they propagate away from the Sun, largely due to the high local magnetosonic speeds closer to the Sun that can suppress shock formation except in extremely fast events. These findings provide new insights into the dynamic processes governing shock evolution in the inner heliosphere, including scenarios where the near-radial magnetic field geometry may lead to predominantly quasi-parallel shock configurations and thus affect near-Sun particle acceleration efficiency. We also provide strong evidence for the existence of slow-mode shocks near the Sun, contributing to the understanding of shock formation and evolution in the inner heliosphere.
The Solar and Geomagnetic Storms in 2024 May: A Flash Data Report
(AAS, 2025-01-16) Hayakawa, Hisashi; Ebihara, Yusuke; Mishev, Alexander; Koldobskiy, Sergey; Kusano, Kanya; Bechet, Sabrina; Yashiro, Seiji; Iwai, Kazumasa; Shinbori, Atsuki; Mursula, Kalevi; Miyake, Fusa; Shiota, Daikou; Silveira, Marcos V. D.; Stuart, Robert; Oliveira, Denny; Akiyama, Sachiko; Ohnishi, Kouji; Ledvina, Vincent; Miyoshi, Yoshizumi
In 2024 May, the scientific community observed intense solar eruptions that resulted in a great geomagnetic storm and auroral extensions, highlighting the need to document and quantify these events. This study mainly focuses on their quantification. The source active region (AR; NOAA Active Region 13664) evolved from 113 to 2761 millionths of the solar hemisphere between May 4 and 14. NOAA AR 13664’s magnetic free energy surpassed 10³³ erg on May 7, triggering 12 X-class flares on May 8–15. Multiple interplanetary coronal mass ejections (ICMEs) were produced from this AR, accelerating solar energetic particles toward Earth. According to satellite and interplanetary scintillation data, at least four ICMEs erupted from AR 13664, eventually overcoming and combining each other. The shock arrival at 17:05 UT on May 10 significantly compressed the magnetosphere down to ≈5.04 Rₑ and triggered a deep Forbush Decrease. GOES satellite data and ground-based neutron monitors confirmed a ground-level enhancement from 2 UT to 10 UT on 2024 May 11. The ICMEs induced exceptional geomagnetic storms, peaking at a provisional Dst index of −412 nT at 2 UT on May 11, marking the sixth-largest storm since 1957. The AE and AL indices showed great auroral extensions that located the AE/AL stations into the polar cap. We gathered auroral records at that time and reconstructed the equatorward boundary of the visual auroral oval to 29.°8 invariant latitude. We compared naked-eye and camera auroral visibility, providing critical caveats on their difference. We also confirmed global disturbances of the storm-enhanced density of the ionosphere.
Connecting energetic electrons at the Sun and in the heliosphere through X-ray and radio diagnostics
(A&A, 2025-02-07) Paipa-Leon, David; Vilmer, Nicole; Maksimovic, Milan; Krupar, Vratislav; Vecchio, Antonio
Solar flares release huge amounts of energy, a considerable part of which is channeled into particle acceleration in the lower corona. Hard X-ray (HXR) emissions are used to diagnose the accelerated electrons that bombard the chromosphere, while type III radio bursts result from energetic electron beams propagating through the corona and into interplanetary space. The Solar Orbiter mission, launched in 2020, aims to link solar flare remote observations with heliospheric events, thus producing useful observations for our understanding of particle acceleration and propagation from the Sun to the heliosphere. While both hard X-Ray and radio emissions result from flare-accelerated electrons, their relationship is not straightforward. By comparing the evolution of the X-ray emitting sites and the timing of type III bursts, our aim is to determine the conditions for associations between X-ray flares and interplanetary (IP) type III bursts. We analyzed 15 interplanetary type III bursts that are associated with HXR bursts in the first available period for simultaneous X-ray/radio observations of type III bursts from Solar Orbiter (using the RPW and STIX instruments). X-ray imaging was performed around the onset of the type III bursts, complemented by EUI 174 A images to assess the magnetic configuration of the corona. All 15 X-ray flares originated from the same active region on the west limb as observed by Solar Orbiter. In each of the events, a change in X-ray source morphology occurred shortly (<6 minutes) before the onset of type III radio bursts, indicating a change in the electron acceleration region preceding the radio emission. Considering the delays observed between the two emissions, these findings describe complex scenarios with multiple reconnection episodes, some of which may allow accelerated electrons to escape into IP space when open magnetic field lines are involved (interchange reconnection). In some cases, X-ray source elongations toward open field lines in the UV were observed, reinforcing this idea.
Detection asymmetry in solar energetic particle events
(2024-11-12) Dalla, S.; Hutchinson, Adam; Hyndman, R. A.; Kihara, K.; Nitta, N.; Rodriguez-Garcia, L.; Laitinen, T.; Waterfall, C. O. G.; Brown, D. S.
Context. Solar energetic particles (SEPs) are detected in interplanetary space in association with flares and coronal mass ejections (CMEs) at the Sun. The magnetic connection between the observing spacecraft and the solar active region (AR) source of the event is a key parameter in determining whether SEPs are observed and the properties of the particle event. Aims. We investigate whether an east-west asymmetry in the detection of SEP events is present in observations and discuss its possible link to corotation of magnetic flux tubes with the Sun. Methods. We used a published dataset of 239 CMEs recorded between 2006 and 2017 and having source regions both on the front side and far side of the Sun as seen from Earth. We produced distributions of occurrence of in-situ SEP intensity enhancements associated with the CME events, versus \Delta \phi, the separation in longitude between the source active region and the magnetic footpoint of the observing spacecraft based on the nominal Parker spiral. We focused on protons of energy >10 MeV measured by the STEREO A, STEREO B and GOES spacecraft at 1 au. We also considered the occurrence of 71-112 keV electron events detected by MESSENGER between 0.31 and 0.47 au. Results. We find an east-west asymmetry in the detection of >10 MeV proton events and of 71-112 keV electron events. For protons, observers for which the source AR is on the east side of the spacecraft footpoint and not well connected (-180 < \Delta \phi < -40) are 93% more likely to detect an SEP event compared to observers with +40 < \Delta \phi < +180. The asymmetry may be a signature of corotation of magnetic flux tubes with the Sun, given that for events with \Delta \phi < 0 corotation sweeps the particle-filled flux tubes towards the observing spacecraft, while for \Delta \phi > 0 it takes them away from it.
Additions to Space Physics Data Facility and pysatNASA: Increasing Mars Global Surveyor and Mars Atmosphere and Volatile EvolutioN Dataset Utility
(MDPI, 2024-11-08) Esman, Teresa; Halford, Alexa J.; Klenzing, Jeff; Burrell, Angeline G.
The Space Physics Data Facility (SPDF) is a digital archive of space physics data and is useful for the storage, analysis, and dissemination of data. We discuss the process used to create an amended dataset and store it on the SPDF. The operational software to generate the archival data software uses the open-source Python package pysat, and an end-user module has been added to the pysatNASA module. The result is the addition of data products to the Mars Global Surveyor (MGS) magnetometer (MAG) dataset, its archival location on SPDF, and pysat compatibility. The primary and metadata format increases the convenience and efficiency for users of the MGS MAG data. The storage of planetary and heliophysics data in one location supports the use of data throughout the solar system for comparison, while pysat compatibility enables loading data in an identical format for ease of processing. We encourage the use of the outlined process for past, present, and future space science missions of all sizes and funding levels. This includes balloons to Flagship-class missions.
The 10 October 2024 geomagnetic storm may have caused the premature reentry of a Starlink satellite
(2024-11-03) Oliveira, Denny; Zesta, Eftyhia; Nandy, Dibyendu
In this short communication, we qualitatively analyze possible effects of the 10 October 2024 geomagnetic storm on accelerating the reentry of a Starlink satellite from low-Earth orbit (LEO). The storm took place near the maximum of solar cycle (SC) 25, which has shown to be more intense than SC24. Based on preliminary geomagnetic indices, the 10 October 2024, along with the 10 May 2024, were the most intense events since the well-known Halloween storms of October/November 2003. By looking at a preliminary version of the Dst index and two-line element (TLE) altitude data of the Starlink-1089 (SL1089) satellite, we observe a possible connection between storm main phase onset and a sharp decay of SL1089. The satellite was scheduled to reenter on 22 October, but it reentered on 12 October, 10 days before schedule. The sharp altitude decay of SL1089 revealed by TLE data coincides with the storm main phase onset. Therefore, we call for future research to establish the eventual causal relationship between storm occurrence and satellite orbital decay. As predicted by previous works, SC25 is already producing extreme geomagnetic storms with unprecedented satellite orbital drag effects and consequences for current megaconstellations in LEO.
Observation of O+ Characteristics During the Terrestrial Alfvén Wing State Induced by the April 2023 Coronal Mass Ejection
(2024-10-28) Liang, Haoming; Chen, Li-Jen; Fuselier, Stephen A.; Gomez, Roman G.; Burkholder, Brandon; Bessho, Naoki; Gurram, Harsha; Rice, Rachel C.; Shuster, Jason; Ardakani, Akhtar S.
We report Magnetospheric Multiscale observations of oxygen ions (O+) during a coronal mass ejection in April 2023 when the solar wind was sub-Alfvénic and Alfvén wings formed. For the first time, O+ characteristics are studied at the contact region between the unshocked solar wind and the magnetosphere. The O+ ions show energies between 100s eV and ~30 keV. The possible sources are the ring current, the warm plasma cloak, and the ionosphere. The O+ ions exhibit bi-directional streaming along newly-formed closed field lines (CFLs), and dominantly anti-parallel on earlier-formed CFLs. Escaping O+ ions in the unshocked solar wind are observed. During the recovery phase, the O+ pitch-angle distribution associated with flux tubes shows dispersion, indicating potential loss to the solar wind. Our results show escaping as well as trapped O+ ions in the region where a magnetic cloud, an Alfvén wing, and magnetospheric field lines are mixed.
A Rapid Sequence of Solar Energetic Particle Events Associated with a Series of Extreme-ultraviolet Jets: Solar Orbiter, STEREO-A, and Near-Earth Spacecraft Observations
(IOP, 2024-10-25) Lario, D.; Balmaceda, L. A.; Gómez-Herrero, R.; Mason, G. M.; Krupar, Vratislav; Cormack, C. Mac; Kouloumvakos, A.; Cernuda, I.; Collier, H.; Richardson, I. G.; Kumar, P.; Krucker, S.; Carcaboso, F.; Wijsen, N.; Strauss, R. D.; Dresing, N.; Warmuth, A.; Rodríguez-Pacheco, J.; Rodríguez-García, L.; Jebaraj, I. C.; Ho, G. C.; Buĉík, R.; Pacheco, D.; Lara, F. Espinosa; Hutchinson, Adam; Horbury, T. S.; Rodríguez, L.; Janitzek, N. P.; Zhukov, A. N.; Aran, A.; Nitta, N. V.
A series of solar energetic electron (SEE) events was observed from 2022 November 9 to November 15 by Solar Orbiter, STEREO-A, and near-Earth spacecraft. At least 32 SEE intensity enhancements at energies >10 keV were clearly distinguishable in Solar Orbiter particle data, with 13 of them occurring on November 11. Several of these events were accompanied by ≲10 MeV proton and ≲2 MeV nucleon⁻¹ heavy-ion intensity enhancements. By combining remote-sensing and in situ data from the three viewpoints (Solar Orbiter and STEREO-A were ∼20° and ∼15° east of Earth, respectively), we determine that the origin of this rapid succession of events was a series of brightenings and jetlike eruptions detected in extreme ultraviolet (EUV) observations from the vicinity of two active regions. We find a close association between these EUV phenomena, the occurrence of hard X-ray flares, type III radio bursts, and the release of SEEs. For the most intense events, usually associated with extended EUV jets, the distance between the site of these solar eruptions and the estimated magnetic connectivity regions of each spacecraft with the Sun did not prevent the arrival of electrons at the three locations. The capability of jets to drive coronal fronts does not necessarily imply the observation of an SEE event. Two peculiar SEE events on November 9 and 14, observed only at electron energies ≲50 keV but rich in ≲1 MeV nucleon⁻¹ heavy ions, originated from slow-rising confined EUV emissions, for which the process resulting in energetic particle release to interplanetary space is unclear.
MARBLE: How to make an open science global magnetosphere code?
(2023-10-09) Bard, Christopher; Dorelli, John; da Silva, Daniel; Khazanov, George; Sur, Dibyendu
The Magnetosphere-Aurora Boundary Layer Explorer (MARBLE) is a currently-under-development global magnetosphere code which will solve the "kinetic Hall MHD" equations. Although NASA now requires all newly funded scientific software to be open source, this is in sharp contrast to the traditionally closed-development ecosystem of global magnetosphere codes. MARBLE, currently being built from the ground up, presents a unique opportunity to develop a large-scale, production code right from the outset with open science principles at its core. While MARBLE's primary objective is to simulate magnetospheric impacts on auroral physics, our stretch goal is to provide a platform for the development of a community, open-source global magnetosphere code. Such a code, in order to be useful, needs to be powerful, accessible, understandable, and seamlessly fit into existing scientific analysis workflows. To achieve this vision, we have chosen to write MARBLE in Python. This provides several advantages, including more rapid development and compatibility with community open source libraries such as Kamodo, SunPy, SpacePy, and others in the PyHC ecosystem. Although pure Python itself is slow, we take advantage of helper libraries such as Numba and CuPy to accelerate low-level arithmetic calculations. The use of Python also enables us to adopt a modular approach to model development. This modularity streamlines addition, substitution, and development of desired features, resulting in a flexible and adaptable resource for the community. We envision this kind of open-source community model as a teaching code, a testbed for prototype development, and a means to more easily ingest and make accessible advanced features from privately developed global codes.
Enabling Unprecedented Exploration of Kinetic Plasma Phenomena: Utilizing and Reaching Beyond the MMS FPI Breakthrough
(AAS, 2023-07-31) Shuster, Jason; Gershman, Daniel; Bessho, Naoki; Wang, Shan; Uritsky, Vadim; Chen, Li-Jen; Gurram, Harsha; Sharma, A. Surjalal; Dorelli, John; Burch, James; Webster, James; Schwartz, Steven; Denton, Richard; Cassak, Paul; Stawarz, Julia; Ng, Jonathan; Paterson, William; Schiff, Conrad; Viñas, Adolfo; Avanov, Levon; Liu, Yi-Hsin; Li, Tak Chu; Argall, Matthew; Torbert, Roy; Afshari, Arya; Payne, Dominic; Farrugia, Charles; Genestreti, Kevin; Verniero, Jaye; Wilder, Frederick; da Silva, Daniel; Haggerty, Colby
The spectrometer suites onboard NASA’s Magnetospheric Multiscale (MMS) mission offered us an unexpected breakthrough in measurement capability that no spacecraft or laboratory experiment has achieved previously: the ingeniously engineered FPI dual ion and electron spectrometers enable direct measurement of terms in the Vlasov equation for the first time in the history of plasma physics research.
Research to Operations Visualization for WSA Coronal and Solar Wind Predictions
(2023-10-09) Landeros, Jaime A.; da Silva, Daniel; Arge, C. Nick; Jones, Shaela I.
The Wang-Sheeley-Arge (WSA) Model has served both the research and operational communities with ambient solar wind forecasts for over a decade, but it has lacked an interactive, centralized, and publicly accessible method for visualizing its empirical and physics-based corona and solar wind predictions. A browser-based dashboard has been developed to fill this gap by providing forecasters with the ability to juxtapose recent in situ and remotely sensed satellite observations and model predictions to assess model performance. It will also serve a complementary purpose of science-enablement through investigation of the model’s detailed ensemble predictions from various satellite perspectives and comparison with observations. Visualized data include time series plots of solar wind speed and interplanetary magnetic field (IMF) polarity, as well as projected maps of derived coronal holes overlayed on EUV coronal hole and filament observations, the heliospheric current sheet location at 5 solar radii, and probabilistic predictions of satellite-footpoint connectivity. Predictions are available for satellites dispersed throughout the Heliospheric System Observatory, including ACE, STEREO-A, PSP, and SolO. The project has been developed with maintainability and ease of deployment in mind with the Plotly Dash framework in Python, targeted JS functions to reduce latency, Git version control, and Docker containerization.
Helionauts: A Cross-Organization Heliophysics Forum
(2023-10-05) Attie, Raphael; Kirk, Michael; Bard, Christopher; Thompson, Barbara; da Silva, Daniel; Narock, Ayris; Mason, Emily; Pesnell, Dean; Zarro, Dominic; Addison, Kevin; Thomas, Brian
The COVID-19 pandemic highlighted the need for a lasting community-wide discussion platform in the field of Heliophysics, supplementing in-person interactions at conferences and within local departments. To address this, instant messaging apps like Slack and Teams were hastily adopted, but their constant online presence requirements posed problems: overlapping content and information sprawl across various chat workspaces, confusion about where discussions should take place. To provide a more coherent landscape for written communication, NASA is backing Helionauts.org, a permanent platform for heliophysicists. It features topic-based and searchable discussions, smart notifications for asynchronous conversations, and supports technical conversations with Markdowns, LaTeX, and code syntax highlighting. The platform fosters inclusivity, connecting experts, postdocs, and students to promote knowledge-sharing and collaboration in our heliophysics community.
Transformer-Based Neural Video Compression on Solar Imagery
(AMS, 2024-01-30) Khoshkhahtinat, Atefeh; Zafari, Ali; Mehta, Piyush M.; Nasrabadi, Nasser; Thompson, Barbara J.; Kirk, Michael; da Silva, Daniel
NASA's Solar Dynamics Observatory (SDO) mission gathers extensive data on the Sun's daily activities. For space missions, data compression is essential to minimize data storage and video bandwidth needs by eliminating data redundancies. In this paper, we introduce an innovative neural Transformer-based approach for video compression, tailored specifically for SDO images. Our main goal is to efficiently leverage both temporal and spatial redundancies inherent in solar images to achieve a substantial compression ratio. Our proposed architecture incorporates a distinctive Transformer block termed Fused Local-aware Window (FLaWin). This block integrates window-based self-attention modules and an efficient Fused Local-aware Feed-Forward (FLaFF) network. This unique design allows us to simultaneously capture short-range and long-range information while facilitating the extraction of diverse and comprehensive contextual representations. Furthermore, this design choice results in a reduction of computational complexity. Experimental findings underscore the significant contribution of the FLaWin Transformer block to compression performance, surpassing conventional hand-engineered video codecs like H.264 and H.265 in terms of rate-distortion performance.
Quantifying adiabatic motion in the outer radiation belt and ring current with invariant matching
(frontiers, 2024-05-29) da Silva, Daniel; Elkington, S. R.; Li, X.; Hudson, M. K.
Adiabatic motion is a fundamental reversible process for geomagnetically trapped particle populations, including particles comprising the ring current and radiation belts. During adiabatic motion, a particle’s trajectory in configuration space responds to sufficiently slow changes in the magnetospheric magnetic field. Previous research has highlighted expected patterns in adiabatic motion, such as radial motion or the Dst effect. In this work, we introduce a method we call Invariant Matching for quantifying adiabatic motion between a pair of magnetospheres. This method can be applied to both simulation and semi-empirical magnetic field models, is computationally efficient, and in particular does not require tracing the particle trajectories. In this work, we use the Tsyganenko et al., Journal of Geophysical Research: Space Physics, 2005, 110 (TS05) magnetic field model, and present adiabatic motion between a storm commencement, the time of the storm’s Dst minimum, and a nominal recovery time. We also analyze adiabatic motion which occurs in response to enhancements of individual major current systems (including the ring current, Chapman-Ferraro current, Birkeland current, and tail current). Our methodology yields vector fields quantifying the displacement of mirror points throughout the magnetosphere, prepared in a way appropriate for application to both outer radiation belt and ring current populations.
Numerical Calculations of Adiabatic Invariants From MHD-Driven Magnetic Fields
(AGU, 2024) da Silva, Daniel; Elkington, S. R.; Li, X.; Murphy, J.; Hudson, M. K.; Wiltberger, M. J.; Chan, A. A.
The adiabatic invariants (M, J, Φ) and the related invariants (M, K, L*) have been established as effective coordinate systems for describing radiation belt dynamics at a theoretical level, and through numerical techniques, can be paired with in situ observations to order phase-space density. To date, methods for numerical techniques to calculate adiabatic invariants have focused on empirical models such the Tsyganenko models TS05, T96, and T89. In this work, we develop methods based on numerical integration and variable step size iteration for the calculation of adiabatic invariants, applying the method to the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamics (MHD) simulation code, with optional coupling to the Rice Convection Model (RCM). By opening the door to adiabatic invariant modeling with MHD magnetic fields, the opportunity for exploratory modeling work of radiation belt dynamics is enabled. Calculations performed using LFM are cross-referenced with the same code applied to the T96 and TS05 Tsyganenko models evaluated on the LFM grid. Important aspects of the adiabatic invariant calculation are reviewed and discussed, including (a) sensitivity to magnetic field model used, (b) differences in the problem between quiet and disturbed geomagnetic states, and (c) the selection of key parameters, such as the magnetic local time step size for drift shell determination. The rigorous development and documentation of this algorithm additionally acts as preliminary step for future thorough reassessment of in situ phase-space density results using alternative magnetic field models.
Neural-Based Video Compression on Solar Dynamics Observatory Images
(IEEE, 2024-06-04) Khoshkhahtinat, Atefeh; Zafari, Ali; Mehta, Piyush M.; Nasrabadi, Nasser M.; Thompson, Barbara J.; Kirk, Michael S. F.; da Silva, Daniel
NASA's Solar Dynamics Observatory (SDO) mission collects extensive data to monitor the Sun's daily activity. In the realm of space mission design, data compression plays a crucial role in addressing the challenges posed by limited telemetry rates. The primary objective of data compression is to facilitate efficient data management and transmission to work within the constrained bandwidth, thereby ensuring that essential information is captured while optimizing the utilization of available resources. This article introduces a neural video compression technique that achieves a high compression ratio for the SDO's image data collection. The proposed approach focuses on leveraging both temporal and spatial redundancies in the data, leading to a more efficient compression. In this work, we introduce an architecture based on the transformer model, which is specifically designed to capture both local and global information from input images in an effective and efficient manner. In addition, our network is equipped with an entropy model that can accurately model the probability distribution of the latent representations and improves the speed of the entropy decoding step. The entropy model leverages a channel-dependent approach and utilizes checkerboard-shaped local and global spatial contexts. By combining the transformer-based video compression network with our entropy model, the proposed compression algorithm demonstrates superior performance over traditional video codecs like H.264 and H.265, as confirmed by our experimental results.
Radiation belt phase space density: calculation analysis and model dependence
(frontiers, 2024-07-04) Wiltberger, Michael; Jaynes, Allison; Boyd, Alexander; Li, Xinlin; Elkington, Scot; da Silva, Daniel
The reprocessing of radiation belt electron flux measurements into phase space density (PSD) as a function of the adiabatic invariants is a widely-used method to address major questions regarding electron energization and loss in the outer radiation belt. In this reprocessing, flux measurements j (α, E) at local pitch angles α, energies E, and optionally magnetometer measurements B, are combined with a global magnetic field model to express the phase space density f (L*) in terms of the third invariant Φ ∝ 1/L* at fixed first and second invariants M and K. While the general framework of the calculation is agreed upon, implementation details vary amongst the literature, and the issue of magnetic field model dependence is rarely addressed. This work reviews the steps of the calculation with lists of commonly used implementation options. For the first time, analysis is presented to display the effect of doing the calculation with different implementation options and with different backing models (including both empirical and MHD-driven models). The results are summarized to inform evaluation of existing results and future efforts calculating and analyzing radiation belt electron phase space density. Three events are analyzed, and while differences are found, the primary structural interpretations of the phase space density analysis exhibit model independence.
Turning SDO Noise Into Van Allen Radiation Belt Characterization Data
(NTRS, 2024-08) Kasapis, Spiridon; Shalaby, Omar; Thompson, Barbara J.; Rodriguez, Juan V.; Attie, Raphael; Padin, Gonzalo Cucho; da Silva, Daniel; Jin, Meng; Pesnell, William D.

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