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Kirolosse M. Girgis, Tohru Hada, Akimasa Yoshikawa, Shuichi Matsukiyo, Viviane Pierrard, Susan W. Samwel, Geomagnetic Storm Effects on the LEO Proton Flux During Solar Energetic Particle Events, Space Weather, 10.1029/2023sw003664, 21, 12, 2023.12, Abstract
During a few solar energetic particle (SEP) events, solar protons were trapped within the geomagnetic field and reached the outer edge of the inner radiation belt. We reproduced this phenomenon by modeling the proton flux distribution at the Low‐Earth Orbit (LEO) for different geomagnetic conditions during solar particle events. We developed a three‐dimensional relativistic test particle simulation code to compute the 70–180 MeV solar proton Lorentz trajectories in low L‐shell range from 1 to 3. The Tsyganenko model (T01) generated the background static magnetic field with the IGRF (v12) model. We have selected three Dst index values: −7, −150, and −210 nT, to define quiet time, strong, and severe geomagnetic storms and to generate the corresponding inner magnetic field configurations. Our results showed that the simulated solar proton flux was more enhanced in the high‐latitude regions and more expanded toward the lower latitude range as long as the geomagnetic storm was intensified. Satellite observations and geomagnetic cutoff rigidities confirmed the numerical results. Furthermore, the LEO proton flux distribution was deformed, so the structure of the proton flux inside the South Atlantic Anomaly (SAA) became longitudinally extended as the Dst index decreased. Moreover, we have assessed the corresponding radiation environment of the LEO mission. We realized that, for a higher inclined LEO mission during an intense geomagnetic storm (Dst = −210 nT), the probability of the occurrence of the Single Event Upset (SEU) rates increased by 19% and the estimated accumulated absorbed radiation doses increased by 17% in comparison with quiet conditions.. |
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Kirolosse M. Girgis, Tohru Hada, Shuichi Matsukiyo, Akimasa Yoshikawa, Radiation Analysis of LEO Mission in the South Atlantic Anomaly during Geomagnetic Storm, IEEE Journal of Radio Frequency Identification, 10.1109/JRFID.2022.3163441, 6, 292-298, 2022.04, We have studied the radiation environment of LEO spacecraft when passing through the South Atlantic Anomaly (SAA) during the geomagnetic storm event of 15 May 2005. The 70-180 MeV proton flux information were numerically obtained from a simulation model of the inner radiation belt. The radiation analysis was consisted of two parts: the estimation of the Single Event Upset (SEU) rates and the absorbed radiation doses. One of the characteristics of the SAA at 800 km altitude during the recovery phase of the geomagnetic storm was the enhancement of its southern proton flux cell. It was found that the excess SEU rates and absorbed radiation doses could reach at least 200 % and 70 % respectively during the recovery phase in comparison to the initial phase of the geomagnetic storm. The estimated radiation results were in a good agreement with observations.. |
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Kirolosse M. Girgis, Tohru Hada, Long-Term Variations of the Solar Wind Effects on South Atlantic Anomaly (SAA) using Tsyganenko Model, Proceedings of International Exchange and Innovation Conference on Engineering & Science (IEICES), 4, 2018.10. |
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Kirolosse Girgis, Tohru Hada, Shuichi Matsukiyo, Space Weather Effects on Proton Flux Variations in the South Atlantic Anomaly: A Numerical Study performed by Test Particle Simulations, European Geosciences Union (EGU), 10.5194/egusphere-egu2020-1551, 2020.03, <p>In this study, we assess the hourly variations of the three-dimensional proton flux distribution inside the South Atlantic Anomaly (SAA) during a geomagnetic storm. We have developed a relativistic three-dimensional guiding center test particle simulation code in order to compute the proton trajectories in a time-varying magnetic field background provided by Tsyganenko model TS05 and the corresponding time-varying inductive electric field. The Dst index is the main input parameter to the simulation model, while the maximum proton flux, the area of the SAA calculated below a selected threshold, and the penetration depth of the protons are the main output variables investigated in this study were. Since the LEO spacecraft and human-related activities are already affected by space weather conditions, the South Atlantic Anomaly (SAA) is also believed to create an additional source of risk. As the radiation environment depends essentially on the particle flux, the objective of this study is to estimate quantitatively the proton flux variations inside the South Atlantic Anomaly (SAA) in quiet and in storm conditions. So far, it was found that after several drift periods, the protons in the South Atlantic Anomaly (SAA) could penetrate to lower altitudes during geomagnetic storm event, and that, the SAA maximum flux value and the corresponding area, varied differently with respect to altitudes. Numerical results were compared with observations by NOAA 17 and RD3R2 instrument mounted on International Space Station (ISS).</p>. |
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Kirolosse M. Girgis, Tohru Hada, Shuichi Matsukiyo, Solar wind parameter and seasonal variation effects on the South Atlantic Anomaly using Tsyganenko Models, Earth, Planets and Space, 10.1186/s40623-020-01221-2, 72, 1, 2020.12. |
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Kirolosse M. Girgis, Tohru Hada, Shuichi Matsukiyo, Akimasa Yoshikawa, Inner radiation belt simulations of the proton flux response in the South Atlantic Anomaly during the Geomagnetic Storm of 15 May 2005, Journal of Space Weather and Space Climate, 10.1051/swsc/2021031, 11, 48-48, 2021.09, A test particle simulation code was developed to simulate the inner proton belt response during the intense geomagnetic storm of 15 May 2005. The guiding center model was implemented to compute the proton trajectories with an energy range of 70–180 MeV. The time-varying magnetic field model implemented in the simulations was computed by the Tsyganenko model TS05 with the associated inductive electric field. One of the most important features of the low-earth orbit (LEO) environment is the South Atlantic Anomaly, which imposes a dangerous radiation load on most LEO missions. This research aims to investigate the proton flux variations in the anomaly region with respect to space weather conditions. The results showed that during the main phase of the geomagnetic storm, the proton flux in the SAA decreased, whereas, throughout the initial and recovery phases, the proton flux was increased at most of the altitudes. Satellite measurements confirmed numerical results.. |
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Kirolosse M. Girgis, Tohru Hada, Shuichi Matsukiyo, Estimation of Single Event Upset (SEU) rates inside the SAA during the geomagnetic storm event of 15 May 2005, 2021 IEEE International Conference on Wireless for Space and Extreme Environments (WiSEE), 10.1109/wisee50203.2021.9613828, 9, 2021.10. |
| 8. |
Kirolosse M. Girgis, Tohru Hada, Shuichi Matsukiyo, Seasonal variation and geomagnetic storm index effects on the proton flux response in the South Atlantic Anomaly by test particle simulations, Journal of Atmospheric and Solar-Terrestrial Physics, 10.1016/j.jastp.2021.105808, 228, 105808-105808, 2022.02. |
