GEM: Modeling Dynamics of the Radiation Belts Using Scattering Rates Computed in a Realistic Magnetic Field and Accounting for Adiabatic Effects

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This project will enhance the already existing Versatile Electron Radiation Belt (VERB) model of Earth's radiation belts to include effects that result from the fact that the magnetic field is not a simple dipolar field. The new model will include the effects of adiabatic variations particle fluxes as well as the effects of magnetic local time (MLT) dependent pitch-angel and energy scattering. The Full Diffusion Code (FDC) will be modified to compute scattering rates in a realistic non-dipolar field for various MLT sectors and different values of geomagnetic activity. Comparisons with observations and numerical sensitivity experiments will significantly improve our understanding of dominant acceleration and loss processes in the radiation belts and will provide important tools for understanding data from several upcoming satellite missions. Key questions that will be examined are: (1) what are the mechanisms responsible for the acceleration of particles in the radiation belts? (2) what mechanisms are responsible for the loss of particles from the radiation belts? (3) How does the stretched, non-dipolar magnetic field affect resonant interactions between magnetospheric waves and the radiation belt electrons? (4) How do pitch-angle scattering and energy diffusion vary as a function of radial distance from the Earth (L-shell), the magnetic local time and geomagnetic activity? (5) How does drift-shell splitting affect the phase space density of the particles? This comprehensive analysis will make it possible to quantify the adiabatic effects and also compare the adiabatic changes to the non-adiabatic energization, scattering, and radial transport.Understanding the interactions of magnetospheric waves with the energetic particles in the radiation belts is important for understanding and predicting space weather phenomena. In addition to the relevance of the work to space weather, the project is directly relevant to NSF's Geospace Environment Modeling program. Much of the research for this project will be carried out by a graduate student and a postdoctoral researcher. The project also has relevance to several upcoming space missions such as NASA's Radiation Belt Storm Probe mission.