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Storm‐induced energization of radiation belt electrons: Effect of wave obliquity
Author(s) -
Artemyev A. V.,
Agapitov O. V.,
Mourenas D.,
Krasnoselskikh V.,
Zelenyi L. M.
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50837
Subject(s) - van allen radiation belt , physics , geomagnetic storm , electron , computational physics , geophysics , storm , earth's magnetic field , intensity (physics) , acceleration , atmospheric sciences , magnetosphere , meteorology , magnetic field , classical mechanics , plasma , nuclear physics , optics , quantum mechanics
New Cluster statistics allow us to determine for the first time the variations of both the obliquity and intensity of lower‐band chorus waves as functions of latitude and geomagnetic activity near L ∼5. The portion of wave power in very oblique waves decreases during highly disturbed periods, consistent with increased Landau damping by inward‐penetrating suprathermal electrons. Simple analytical considerations as well as full numerical calculations of quasi‐linear diffusion rates demonstrate that early‐time electron acceleration occurs in a regime of loss‐limited energization. In this regime, the average wave obliquity plays a critical role in mitigating lifetime reduction as wave intensity increases with geomagnetic activity, suggesting that much larger energization levels should be reached during the early recovery phase of storms than during quiet time or moderate disturbances, the latter corresponding to stronger losses. These new effects should be included in realistic radiation belt simulations.