SM042-0005
Quantitative Model of Subauroral Polarization Stream Based on Global MHD Simulations

Tuesday, 15 December 2020
Poster
Banafsheh Ferdousi, University of New Hampshire Main Campus, Durham, NH, United States, Joachim Raeder, University of New Hampshire, Institute for the Study of Earth, Oceans, and Space, Durham, NH, United States, Naomi Maruyama, University of Colorado, Boulder, CO, United States, Philip John Erickson, MIT Haystack Observatory, Westford, MA, United States, William D Cramer, University of New Hampshire, Durham, NH, United States and Ercha Aa, Chinese Academy of Sciences, National Space Science Center, Beijing, China
Abstract:
Subauroral Polarization Streams (SAPS) form as the result of the magnetosphere-ionosphere coupling process. They are identified as northward electric field polarization driving sunward plasma convection. These fast flows are formed in the midlatitude region equatorward of the auroral oval, due to an interplay between region-2 (R2) currents from the

magnetosphere, the low-latitude cutoff of electron precipitation, and the resulting low conductance in the SAPS flow channel. SAPS flows are thought to increase the recombination rate, which further reduces the conductance in the SAPS channel and thus provides a positive feedback that can increase the SAPS strength. While the qualitative SAPS model seems to be well established, it is important to quantify the role of these parameters in SAPS formation.

In this study, we use observations from DMSP and Incoherent Scatter Radar (ISR), as well as the physics-based OpenGGCM-RCM-CTIM model that self consistently simulates the coupled magnetosphere-ionosphere-thermosphere (MIT) system. After comparing simulation result with observation, we perform numerical experiments to investigate the effect of the ionosphere parameters on the SAPS. R2 FAC, recombination rate, electron precipitation, and conductance boundary are modified, and their effects on SAPS is investigated. Initial results show that without recombination SAPS would be significant weaker. Also, turning off the R2 currents in the model basically eliminates the SAPS, showing that the R2 currents are the primary SAPS driver.

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