Loss of radiation belt electrons through the action of broadband electromagnetic waves.

An essential component of the variability in radiation belt populations is the loss of trapped energetic electrons at low altitudes. In this presentation we explore the role of prevalent storm-time broadband electromagnetic fluctuations in driving radiation belt electrons into the atmospheric loss cone. We present observations from a magnetic conjunction between the BARREL balloon array and the Van Allen Probes spacecraft in the outer radiation belt that reveals energetic electron precipitation coincident with broadband electromagnetic fluctuations. Based on these observations we build a model which demonstrates how these waves may drive relativistic electrons into the atmosphere through finite-gyro-radii effects. The evaluation of diffusion coefficients shows that while this process is active over the full range of observed radiation belt electron energies it is most effective in the outer belt at energies above 1 MeV. We compare statistics of wave occurrence and precipitation that are suggestive of the persistent operation of this loss process.