| Autor: |
O'Brien, D., Li, X., Khoo, L., Selesnick, R. S., Hogan, B., Zhao, H., Mei, Y., Hoxie, V., Baker, D. N., Kanekal, S. G. |
| Předmět: |
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| Zdroj: |
Geophysical Research Letters; 1/28/2024, Vol. 51 Issue 2, p1-9, 9p |
| Abstrakt: |
Electrons in Earth's outer radiation belt are highly dynamic, with fluxes changing by up to orders of magnitude. The penetration of electrons from the outer belt to the inner belt is one such change observed during geomagnetic storms and was previously observed in electrons up to 1 MeV for some strong storms observed by the Van Allen Probes. We analyze pulse height analysis data from the Relativistic Electric and Proton Telescope (REPT) on the Van Allen Probes to produce electron flux measurements with lower minimum energy and significantly improved resolution compared to the standard REPT data and show that electron penetrations into the inner belt (L ≤ 2) extend to at least 1.3 MeV and penetrations into the slot region (2 < L < 2.8) extend to at least 1.5 MeV during certain geomagnetic storms. We also demonstrate that these penetrations are associated with butterfly pitch angle distributions from 1 to 1.3 MeV. Plain Language Summary: Electrons in Earth's outer radiation belt are highly dynamic with the amount and energy of them changing drastically, especially during geomagnetic storms. The penetration of electrons from the outer belt to the inner radiation belt is one such change and was previously observed in electrons with energies ≤1 MeV during some of the strongest storms during the Van Allen Probes mission. Electrons in the radiation belts also have a pitch angle that describes what portion of their motion is along or perpendicular to the direction of the magnetic field. Pitch angle distributions (PAD) are often used to gain information on the dynamics of the electrons, as unstable distributions can be caused by and indicative of wave activity that cannot always be measured directly. PADs with a minimum at 90°, called butterfly PADs, are one such unstable distribution that have previously been observed in penetrating electrons with energies ∼100–900 keV. We use instrument simulation to analyze data from the Van Allen Probes that could not previously be analyzed to show that the maximum energy of these penetrations is higher than previously observed, up to 1.3 MeV, and that these penetrations are associated with butterfly PADs at 1–1.3 MeV. Key Points: REPT PHA data can be used to produce high energy resolution flux spectra of >1 MeV electronsElectron penetrations below L = 2 during strong geomagnetic storms extend in energy up to 1.3 MeVElectron penetrations below L = 2 at energies 1–1.3 MeV are associated with butterfly pitch angle distributions [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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