GEM: Study the Precipitation of Radiation Belt Electrons during the Rapid Dropout Events

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With the launch of the Van Allen Probes in 2012 a new era in radiation belt studies has begun. This is a project to investigate the scientifically and societally important issue of radiation belt electron dynamics. The emphasis in this research will be on understanding the losses of electrons that occur during magnetic storms. These are significant in that the flux of relativistic electrons decreases by an order of magnitude in a few hours. There are two possible explanations for this: One is loss to the solar wind through the magnetopause and the other is loss to the atmosphere due to precipitation. The former is relatively easy to evaluate but the latter is much more difficult because the loss cone is small in the magnetosphere and because satellite observations provide a limited picture. This proposal will apply a creative approach combining satellite observations from the Van Allen Probes and NOAA POES satellites and a new Drift-Diffusion simulation to quantify the losses. The team will start by determining which observed events are candidates for magnetopause loss, which are candidates for precipitation loss and which are combinations of both types of loss. Then they will use the observations and the simulation iteratively to improve the simulation. They will determine the pitch angle diffusion coefficients as a function of magnetic local time and from that the local time and L shell (radial) dependence of the plasma waves responsible for the precipitation. They will compare this with Van Allen Probes wave observations. They plan a detailed calibration of the POES observations and those from the NSF Colorado Student Space Weather Experiment (CSSWE).Understanding electron dynamics is important societally for understanding space weather. In addition this project will support a young woman scientist and a graduate student. Finally the detailed calibration of the POES and CSSWE data will be useful well beyond this application.