Variations in Energetic Particle Fluxes around Significant Geomagnetic Storms Observed by the Low-Altitude DEMETER Spacecraft
A superposed epoch analysis is conducted for five geomagnetic storms in the years 2005 and 2006 with the aim to understand energetic particle flux variations as a function of L-shell, energy and time from the Dst minimum. Data measured by the low-altitude DEMETER spacecraft were used for this purpos...
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MDPI AG
2021-07-01
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| Series: | Universe |
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| Online Access: | https://www.mdpi.com/2218-1997/7/8/260 |
| _version_ | 1797521961125937152 |
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| author | Stefan Gohl František Němec Michel Parrot |
| author_facet | Stefan Gohl František Němec Michel Parrot |
| author_sort | Stefan Gohl |
| collection | DOAJ |
| description | A superposed epoch analysis is conducted for five geomagnetic storms in the years 2005 and 2006 with the aim to understand energetic particle flux variations as a function of L-shell, energy and time from the Dst minimum. Data measured by the low-altitude DEMETER spacecraft were used for this purpose. The storms were identified by a Dst index below −100 nT, as well as their being isolated events in a seven-day time window. It is shown that they can be categorized into two types. The first type shows significant variations in the energetic particle fluxes around the Dst minimum and increased fluxes at high energies (>1.5 MeV), while the second type only shows increased fluxes around the Dst minimum without the increased fluxes at high energies. The first type of storm is related to more drastic but shorter-lasting changes in the solar wind parameters than the second type. One storm does not fit either category, exhibiting features from both storm types. Additionally, we investigate whether the impenetrable barrier for ultra-relativistic electrons also holds in extreme geomagnetic conditions. For the highest analyzed energies, the obtained barrier L-shells do not go below 2.6, consistent with previous findings. |
| first_indexed | 2024-03-10T08:19:58Z |
| format | Article |
| id | doaj.art-cf875dded2a5496790b0d0e4ebe3fc19 |
| institution | Directory Open Access Journal |
| issn | 2218-1997 |
| language | English |
| last_indexed | 2024-03-10T08:19:58Z |
| publishDate | 2021-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Universe |
| spelling | doaj.art-cf875dded2a5496790b0d0e4ebe3fc192023-11-22T10:05:19ZengMDPI AGUniverse2218-19972021-07-017826010.3390/universe7080260Variations in Energetic Particle Fluxes around Significant Geomagnetic Storms Observed by the Low-Altitude DEMETER SpacecraftStefan Gohl0František Němec1Michel Parrot2Institute of Experimental and Applied Physics, Czech Technical University in Prague, 11000 Prague, Czech RepublicFaculty of Mathematics and Physics, Charles University, 18000 Prague, Czech RepublicLPC2E/CNRS Orléans, 45071 Orléans, FranceA superposed epoch analysis is conducted for five geomagnetic storms in the years 2005 and 2006 with the aim to understand energetic particle flux variations as a function of L-shell, energy and time from the Dst minimum. Data measured by the low-altitude DEMETER spacecraft were used for this purpose. The storms were identified by a Dst index below −100 nT, as well as their being isolated events in a seven-day time window. It is shown that they can be categorized into two types. The first type shows significant variations in the energetic particle fluxes around the Dst minimum and increased fluxes at high energies (>1.5 MeV), while the second type only shows increased fluxes around the Dst minimum without the increased fluxes at high energies. The first type of storm is related to more drastic but shorter-lasting changes in the solar wind parameters than the second type. One storm does not fit either category, exhibiting features from both storm types. Additionally, we investigate whether the impenetrable barrier for ultra-relativistic electrons also holds in extreme geomagnetic conditions. For the highest analyzed energies, the obtained barrier L-shells do not go below 2.6, consistent with previous findings.https://www.mdpi.com/2218-1997/7/8/260geomagnetic stormssolar windearth’s magnetosphereradiation belt |
| spellingShingle | Stefan Gohl František Němec Michel Parrot Variations in Energetic Particle Fluxes around Significant Geomagnetic Storms Observed by the Low-Altitude DEMETER Spacecraft Universe geomagnetic storms solar wind earth’s magnetosphere radiation belt |
| title | Variations in Energetic Particle Fluxes around Significant Geomagnetic Storms Observed by the Low-Altitude DEMETER Spacecraft |
| title_full | Variations in Energetic Particle Fluxes around Significant Geomagnetic Storms Observed by the Low-Altitude DEMETER Spacecraft |
| title_fullStr | Variations in Energetic Particle Fluxes around Significant Geomagnetic Storms Observed by the Low-Altitude DEMETER Spacecraft |
| title_full_unstemmed | Variations in Energetic Particle Fluxes around Significant Geomagnetic Storms Observed by the Low-Altitude DEMETER Spacecraft |
| title_short | Variations in Energetic Particle Fluxes around Significant Geomagnetic Storms Observed by the Low-Altitude DEMETER Spacecraft |
| title_sort | variations in energetic particle fluxes around significant geomagnetic storms observed by the low altitude demeter spacecraft |
| topic | geomagnetic storms solar wind earth’s magnetosphere radiation belt |
| url | https://www.mdpi.com/2218-1997/7/8/260 |
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