A Multi-Platform Statistical Analysis of the Azimuthal Spatial Extent of the Microburst Precipitation Region

Abstract

Microbursts are impulsive injections of energetic (few keV to >MeV) electrons into the atmosphere, primarily caused by nonlinear scattering driven by whistler mode chorus waves. While the relative importance of microburst precipitation as a loss process has not been fully quantified, many studies have shown microbursts may play a significant role in the loss of outer radiation belt electrons. We present a multi-platform statistical analysis of chorus and energetic electron precipitation in an attempt to constrain the azimuthal spatial extent ($∆$MLT) of the microburst precipitation region and determine how this extent varies with geomagnetic activity. Statistical upper bounds of this azimuthal extent are determined with observations of general energetic electron precipitation that can include direct microburst detections, while statistical lower bounds determination requires direct microburst detections. The resulting distributions of both upper and lower bounds azimuthal extent suggest that microbursts may frequently constitute an important source of electron loss from the outer radiation belt. We find that 36% of upper bound events in the dawn sector span more than 5 hr in MLT. This azimuthal extent increases with geomagnetic activity, particularly in the dawn and noon MLT sectors.