Global Radiation Belt Modeling: Combined MHD and Test-Particle Simulations

Sorathia, Kareem

Global Radiation Belt Modeling: Combined MHD and Test-Particle Simulations

Friday, 9 March 2018: 14:10

Longshot and Bogey (Hotel Quinta da Marinha)

Kareem Sorathia¹, Aleksandr Y Ukhorskiy², Viacheslav G Merkin³, Michael James Wiltberger⁴, John Lyon⁵, Seth G Claudepierre⁶ and Joseph F. Fennell⁶, (1)Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (2)Applied Physics Laboratory Johns Hopkins, Laurel, MD, United States, (3)Johns Hopkins University, Baltimore, MD, United States, (4)National Center for Atmospheric Research, High Altitude Observatory, Boulder, CO, United States, (5)Dartmouth College, Hanover, NH, United States, (6)Aerospace Corporation, Los Angeles, CA, United States

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Abstract:

During geomagnetic storms the intensities of radiation belt electrons exhibit dramatic variability. In the main phase electron intensities exhibit deep depletion over a broad region of the outer belt. The intensities then increase during the recovery phase, often to levels that significantly exceed their pre-storm values. In this study we analyze the depletion, recovery and enhancement of radiation belt intensities during the 2013 St. Patrick’s geomagnetic storm. We simulate the dynamics of high-energy electrons using our newly-developed test-particle radiation belt model (CHIMP) based on a hybrid guiding-center/Lorentz integrator and electromagnetic fields derived from high-resolution global MHD (LFM) simulations. Our approach differs from previous work in that we use MHD flow information to identify and seed test-particles into regions of strong convection in the magnetotail. We address two science questions: 1) what are the relative roles of magnetopause losses, transport-driven atmospheric precipitation, and adiabatic cooling in the radiation belt depletion during the storm main phase? and 2) to what extent can enhanced convection/mesoscale injections account for the radiation belt buildup during the recovery phase? Our analysis is based on long-term model simulation and the comparison of our model results with electron intensity measurements from the MAGEIS experiment of the Van Allen Probes mission.