Characterizing radiation belt electron precipitation losses using BARREL (Balloon Array for RBSP Relativistic Electron Losses) data.

Abstract:

Precipitation loss is a process whereby charged particles trapped in the radiation belts scatter into the Earth’s atmosphere and are removed from the belt population. Balloon-borne x-ray detectors and satellites like SAMPEX have generally observed precipitation losses of three types, here characterized by their MLT distribution and related e-folding energy of the inferred precipitating electron energy spectrum, the third characterized by its burstiness and brief duration: soft (isotropic in MLT with e-folding for balloons between 50-100 keV, for SAMPEX between 100-300 keV), hard (concentrated in the dusk-to-midnight sector with e-folding for balloons > 200 keV, for SAMPEX > 400 keV), and microbursts (concentrated in the dawn-to-noon sector, bursty and very short temporal structure < 1s). Soft precipitation occurs much more often than the others, but has received less attention in the literature even though recent analysis of observed SAMPEX losses has shown that soft precipitation may account for the greatest electron loss from the quiet time radiation belts. The goal of this project is to compare/reconcile the different spectral characterizations of soft precipitation observed by BARREL and SAMPEX, and seek to understand the wave scattering mechanisms responsible for these losses.

For this work we will present the 2013/2014 observed BARREL precipitation events cataloged according to type, (soft, hard, microburst), MLT and L distribution, and geomagnetic/space weather conditions. In particular, we will use Van Allen Probe data to define the state of the belts and the position of the balloon relative to the plasmapause and trapping boundary before and after precipitation events.