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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 *
Author(s) -
Zhao H.,
Baker D. N.,
Jaynes A. N.,
Li X.,
Elkington S. R.,
Kanekal S. G.,
Spence H. E.,
Boyd A. J.,
Huang C.L.,
Forsyth C.
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja023658
Subject(s) - solar wind , electron , physics , van allen radiation belt , earth's magnetic field , computational physics , electron precipitation , adiabatic process , coronal mass ejection , atmospheric sciences , atomic physics , astrophysics , magnetosphere , plasma , magnetic field , nuclear physics , quantum mechanics , thermodynamics
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 B z , 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.