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What effect do substorms have on the content of the radiation belts?

What effect do substorms have on the content of the radiation belts?
What effect do substorms have on the content of the radiation belts?
Substorms are fundamental and dynamic processes in the magnetosphere, converting captured solar wind magnetic energy into plasma energy. These substorms have been suggested to be a key driver of energetic electron enhancements in the outer radiation belts. Substorms inject a keV “seed” population into the inner magnetosphere which is subsequently energized through wave-particle interactions up to relativistic energies; however, the extent to which substorms enhance the radiation belts, either directly or indirectly, has never before been quantified. In this study, we examine increases and decreases in the total radiation belt electron content (TRBEC) following substorms and geomagnetically quiet intervals. Our results show that the radiation belts are inherently lossy, shown by a negative median change in TRBEC at all intervals following substorms and quiet intervals. However, there are up to 3 times as many increases in TRBEC following substorm intervals. There is a lag of 1–3?days between the substorm or quiet intervals and their greatest effect on radiation belt content, shown in the difference between the occurrence of increases and losses in TRBEC following substorms and quiet intervals, the mean change in TRBEC following substorms or quiet intervals, and the cross correlation between SuperMAG AL (SML) and TRBEC. However, there is a statistically significant effect on the occurrence of increases and decreases in TRBEC up to a lag of 6?days. Increases in radiation belt content show a significant correlation with SML and SYM-H, but decreases in the radiation belt show no apparent link with magnetospheric activity levels
2169-9380
1-15
Forsyth, C.
f3d464cf-81c5-4647-b85a-bc3634bdf076
Rae, I.
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Murphy, K.
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Freeman, M.
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Huang, C.-L.
f6e8ba4b-7e54-47bf-99fc-1e11adb560d2
Spence, H.
ecfd1bde-36bf-4526-8182-afa63435ed7f
Boyd, A.
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Coxon, J.
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Jackman, C.
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Kalmoni, N.
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Watt, C.
85c02dbf-4e62-4ddb-bc16-b0dd320986a2
Forsyth, C.
f3d464cf-81c5-4647-b85a-bc3634bdf076
Rae, I.
37b017e2-c80a-4427-bb5a-7e477252c001
Murphy, K.
363d292a-e93f-48b4-8c3f-1836de9c2b1c
Freeman, M.
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Huang, C.-L.
f6e8ba4b-7e54-47bf-99fc-1e11adb560d2
Spence, H.
ecfd1bde-36bf-4526-8182-afa63435ed7f
Boyd, A.
6a71d201-5123-49cc-9309-20eef4209533
Coxon, J.
566baea5-6a30-4855-bde3-a09c115efde4
Jackman, C.
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Kalmoni, N.
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Watt, C.
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Forsyth, C., Rae, I., Murphy, K., Freeman, M., Huang, C.-L., Spence, H., Boyd, A., Coxon, J., Jackman, C., Kalmoni, N. and Watt, C. (2016) What effect do substorms have on the content of the radiation belts? Journal of Geophysical Research: Space Physics, pp. 1-15. (doi:10.1002/2016JA022620).

Record type: Article

Abstract

Substorms are fundamental and dynamic processes in the magnetosphere, converting captured solar wind magnetic energy into plasma energy. These substorms have been suggested to be a key driver of energetic electron enhancements in the outer radiation belts. Substorms inject a keV “seed” population into the inner magnetosphere which is subsequently energized through wave-particle interactions up to relativistic energies; however, the extent to which substorms enhance the radiation belts, either directly or indirectly, has never before been quantified. In this study, we examine increases and decreases in the total radiation belt electron content (TRBEC) following substorms and geomagnetically quiet intervals. Our results show that the radiation belts are inherently lossy, shown by a negative median change in TRBEC at all intervals following substorms and quiet intervals. However, there are up to 3 times as many increases in TRBEC following substorm intervals. There is a lag of 1–3?days between the substorm or quiet intervals and their greatest effect on radiation belt content, shown in the difference between the occurrence of increases and losses in TRBEC following substorms and quiet intervals, the mean change in TRBEC following substorms or quiet intervals, and the cross correlation between SuperMAG AL (SML) and TRBEC. However, there is a statistically significant effect on the occurrence of increases and decreases in TRBEC up to a lag of 6?days. Increases in radiation belt content show a significant correlation with SML and SYM-H, but decreases in the radiation belt show no apparent link with magnetospheric activity levels

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Accepted/In Press date: 8 June 2016
e-pub ahead of print date: 14 June 2016
Organisations: Theoretical Partical Physics Group

Identifiers

Local EPrints ID: 397613
URI: http://eprints.soton.ac.uk/id/eprint/397613
ISSN: 2169-9380
PURE UUID: 47b0d516-1215-4eac-8fc6-6d986c8118f4
ORCID for J. Coxon: ORCID iD orcid.org/0000-0002-0166-6854

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Date deposited: 04 Jul 2016 12:48
Last modified: 17 Jul 2017 18:37

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Contributors

Author: C. Forsyth
Author: I. Rae
Author: K. Murphy
Author: M. Freeman
Author: C.-L. Huang
Author: H. Spence
Author: A. Boyd
Author: J. Coxon ORCID iD
Author: C. Jackman
Author: N. Kalmoni
Author: C. Watt

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