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Modeling Storm Time Interhemispheric Asymmetries: What is our capability?

Presented on: December 14, 2020

Presented at: AGU Fall Meeting 2020

Presented by: Daniel Welling, Kevin Pham, Alex Glocer, James Weygand, Christine Gabrielse, Robert Strangeway, Ramon Lopez


Prominent amongst drivers of interhemispheric asymmetries is the BY component of the interplanetary magnetic field (IMF). Global MHD models coupled with ring current models are powerful tools for exploring the effects of BY periods, but their capabilities have not been fully tested against observations. As part of the ongoing work of the Center for the Unified Study of Interhemispheric Asymmetries (CUSIA), we examine the performance of two global MHD models during the September 26, 2011 storm - a period of combined southward IMF and considerable BY component. A strong ring current and associated region 2 Birkeland currents are prevalent during this storm. Both the Block Adaptive Tree Solar wind Roe-type Upwind Scheme (BATS-R-US) and the Lyon-Fedder-Mobarry (LFM) magnetohydrodynamic models, coupled to the Rice Convection Model (RCM) ring current model, will be used to simulate this event. Comparisons to observations from the AMPERE data set, DMSP, and THEMIS missions will be made to test the models’ ability to reproduce magnetopause location, development of the ring current, formation of Birkeland currents, ionospheric precipitation and conductance, and other critical features. Experiments where the ring current coupling switches from the north to south hemisphere or BY is artificially flipped will be performed to see what features are robust to BY and which are most sensitive. Inter-model comparisons will be performed to evaluate how different model assumptions affect development of interhemispheric asymmetries.

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