Advances in characterizing auroral precipitation in a coupled global geospace model and applications in the simulation of SAPS
Abstract
Auroral precipitation plays an important role in the magnetosphere-ionosphere-thermosphere (MIT) coupling. The auroral ionospheric conductance produced by the precipitating charged particles has great impacts on the global ionospheric convection as well as the more localized mesoscale structures. In this study, we make use of a newly developed precipitation model to explore a typical mesoscale structure in the ionosphere, namely the subauroral polarization streams (SAPS). The precipitation model is embedded in the current implementation of the Multiscale Atmosphere Geospace Model (MAGE), which has been developed by the NASA DRIVE Science Center for Geospace Storms (CGS). The mono-energetic electron precipitation is derived from the MHD parameters of the GAMERA global magnetosphere model by solving the current-voltage relation. The diffuse electron precipitation is derived from the Rice Convection Model (RCM) ring current model by integrating over the phase space density of the electrons. These two types of precipitation are then used in the MAGE to characterize the ionospheric conductance. The 17 March 2013 storm event has been simulated and the model results are compared with three DMSP satellites, F16, F17, and F18. The MAGE precipitation energy flux and cross track ion drift velocity sampled along the DMSP trajectories show very good agreement with the DMSP measurements. SAPS structures are reproduced with an overall consistency in terms of the location and magnitude. We further illustrate the driving mechanism of SAPS with the coupled MAGE model by showing that ring current ions penetrate more inward in the magnetosphere than the electrons, forming a gap between the inner boundaries of the ions and electrons. When mapped to the ionosphere, the equatorward boundary of the electron precipitation is at a higher latitude than that of the downward field-aligned current (FAC). The current closure requirement results in an enhanced poleward electric field in the gap which drives the SAPS. In this presentation, we will show the importance of proper characterization of diffuse electron precipitation in resolving the mesoscale structures in the MIT system.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMSA024..05L
- Keywords:
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- 2427 Ionosphere/atmosphere interactions;
- IONOSPHERE;
- 2431 Ionosphere/magnetosphere interactions;
- IONOSPHERE;
- 2704 Auroral phenomena;
- MAGNETOSPHERIC PHYSICS;
- 2736 Magnetosphere/ionosphere interactions;
- MAGNETOSPHERIC PHYSICS