Rodger, Craig J;
Clilverd, Mark A;
Hendry, Aaron T;
Forsyth, Colin;
(2022)
Examination of Radiation Belt Dynamics during Substorm Clusters: Magnetic Local Time Variation and Intensity of Precipitating Fluxes.
Journal of Geophysical Research: Space Physics
, 127
(12)
, Article e2022JA030750. 10.1029/2022ja030750.
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Abstract
Substorms are short-lived but significant reconfigurations of the geomagnetic field during which energetic particles are injected into the inner magnetosphere close to magnetic midnight. There is currently a need to quantify substorm-driven energetic electron precipitation (EEP) to better understand its role in radiation belt dynamics and to quantify its impact on the atmosphere. As substorm injections trigger chorus waves, which have strong MLT, AE, and L-shell dependence, we investigate the dependence of EEP in terms of these variables. We utilize many decades of low Earth orbit satellite observations to examine the typical statistical variability around substorm events identified by the Substorm Onsets and Phases from Indices of the Electrojet (SOPHIE) algorithm. In contrast to trapped flux enhancements, enhanced EEP is found to occur even for the quietest AE range of those considered (AE ≤ 100 nT, 100 nT < AE ≤ 300 nT, AE ≥ 300 nT). The MLT-dependent analysis for all AE-ranges shows a well-defined variation in >30 keV EEP magnitude, with a distinct and deep minimum in the late afternoon sector (15–18 MLT), and maxima in the mid to late morning sector (6–12 MLT). The patterns show similarities to previously published whistler-mode lower band chorus distributions with MLT. Clusters of substorms reliably produce enhancements in electron precipitation for >30 keV and >300 keV, with steadily increasing peak precipitation magnitudes with increasing AE. The peak precipitation flux L-shell also moves inwards with increasing AE, in a similar way for the two energy ranges.
| Type: | Article |
|---|---|
| Title: | Examination of Radiation Belt Dynamics during Substorm Clusters: Magnetic Local Time Variation and Intensity of Precipitating Fluxes |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1029/2022ja030750 |
| Publisher version: | https://doi.org/10.1029/2022ja030750 |
| Language: | English |
| Additional information: | Copyright © 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
| Keywords: | radiation belt electrons, radiation belt precipitation, magnetospheric substorm, whistler mode chorus |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10162062 |
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