Electron Dynamics in Kinetic Scale Field Line Resonances.

Van Allen probes observations of electron distributions within kinetic scale field line resonances (KFLRs) exhibit a pronounced elongation in the direction of parallel velocity, centered about the origin. Cluster observations of KFLRs on similar L-shells, but at higher latitudes, illustrate a similar elongation that is however asymmetric about the origin and skewed in the direction opposite in sign to that of the parallel current. In this work, we compare these observations with results of kinetic simulations of KFLRs and illustrate that the noted characteristics of both the Cluster and Van Allen probes observations are consistent with electron distribution evolution in the standing Alfven wave parallel electric field.