On the relation between radiation belt electrons and solar wind parameters/geomagnetic indices: Dependence on the first adiabatic invariant and L

H Zhao; D. N Baker; A. N Jaynes; X Li; S. R Elkington; S. G Kanekal; H. E Spence; A. J Boyd; C.‐L Huang; C Forsyth

doi:10.1002/2016JA023658

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On the relation between radiation belt electrons and solar wind parameters/geomagnetic indices: Dependence on the first adiabatic invariant and L

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On the relation between radiation belt electrons and solar wind parameters/geomagnetic indices: Dependence on the first adiabatic invariant and L

H Zhao, D. N Baker, A. N Jaynes, X Li, S. R Elkington, S. G Kanekal, H. E Spence, A. J Boyd, C.‐L Huang and C Forsyth

Journal of geophysical research. Space physics, Vol.122(2), pp.1624-1642

02/2017

DOI: 10.1002/2016JA023658

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Abstract

The relation between radiation belt electrons and solar wind/magnetospheric processes is of particular interest due to both scientific and practical needs. Though many studies have focused on this topic, electron data from Van Allen Probes with wide L shell coverage and fine energy resolution, for the first time, enabled this statistical study on the relation between radiation belt electrons and solar wind parameters/geomagnetic indices as a function of first adiabatic invariant μ and L*. Good correlations between electron phase space density (PSD) and solar wind speed, southward IMF Bz, SYM‐H, and AL indices are found over wide μ and L* ranges, with higher correlation coefficients and shorter time lags for low‐μ electrons than high‐μ electrons; the anticorrelation between electron PSD and solar wind proton density is limited to high‐μ electrons at high L*. The solar wind dynamic pressure has dominantly positive correlation with low‐μ electrons and negative correlation with high‐μ electrons at different L*. In addition, electron PSD enhancements also correlate well with various solar wind/geomagnetic parameters, and for most parameters this correlation is even better than that of electron PSD while the time lag is also much shorter. Among all parameters investigated, AL index is shown to correlate the best with electron PSD enhancements, with correlation coefficients up to ~0.8 for low‐μ electrons (time lag ~ 0 day) and ~0.7 for high‐μ electrons (time lag ~ 1–2 days), suggesting the importance of seed and source populations provided by substorms in radiation belt electron PSD enhancements. Key Points The correlation between radiation belt electrons and solar wind/geomagnetic parameters as a function of μ and L* has been unveiled Various solar wind/geomagnetic parameters correlate better with the enhancements of electron phase space density (PSD) than electron PSD Among all parameters investigated, AL index correlates the best with electron PSD enhancements, with correlation coefficients up to ~0.8

geomagnetic storms

magnetospheric substorms

phase space density

radiation belt electron content

radiation belt electrons

solar wind

Details

Title: Subtitle: On the relation between radiation belt electrons and solar wind parameters/geomagnetic indices: Dependence on the first adiabatic invariant and L
Creators: H Zhao - University of Colorado Boulder
D. N Baker - University of Colorado Boulder
A. N Jaynes - University of Colorado Boulder
X Li - University of Colorado Boulder
S. R Elkington - University of Colorado Boulder
S. G Kanekal - Goddard Space Flight Center
H. E Spence - University of New Hampshire
A. J Boyd - Los Alamos National Laboratory
C.‐L Huang - University of New Hampshire
C Forsyth - University College London
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.122(2), pp.1624-1642
DOI: 10.1002/2016JA023658
ISSN: 2169-9380
eISSN: 2169-9402
Number of pages: 19
Language: English
Date published: 02/2017
Academic Unit: Physics and Astronomy; University College Courses
Record Identifier: 9984200060102771

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