Magnetospheric convection and magnetopause shadowing effects in ULF wave-driven energetic electron transport

Abstract

Magnetospheric radiation belt electron transport in the presence of ULF waves and a convection electric field is investigated using a model that includes a nightside plasma sheet source and electron losses by magnetopause shadowing. Narrow-band ULF waves launched from a prescribed dayside magnetopause source are shown to interact with trapped and untrapped equatorially mirroring electrons within the magnetosphere. For magnetic moments less than 8 keV/nT and a strong convection electric field (in the order of 5 mV/m), we find that a limb of untrapped plasma sheet electrons extending across the dayside magnetosphere into the afternoon sector provides a phase space density (PSD) source for injection to lower L-shells by ULF waves, causing a rapid enhancement in PSD. However, the same ULF wave activity gives rise to a rapid dropout in PSD for electrons with a higher magnetic moment or in the presence of a weaker convection electric field, since in this case the plasma sheet electrons escape through the magnetopause before they reach the afternoon sector. In their place, a lack of PSD, or PSD "holes" can be periodically injected from the magnetopause to lower L-shells by ULF waves, leading to the rapid depletion in average PSD. In each case, the magnitude and extent in L-shell of the PSD enhancement or depletion is strongly dependent on the amplitude of ULF waves in the afternoon sector, and is significantly augmented by the overlap of drift-resonant islands and an associated stochastic transport layer. Key Points ULF wave electron interactions are modeled with convection and magnetopause loss PSD enhancement(drop-out) results for strong (weak) convection and low (high) M This depends on the presence (absence) of an afternoon sector plasmasheet source ©2013. American Geophysical Union. All Rights Reserved.