Association of SAPS Morphology with Ionosphere Parameters

Subauroral Polarization Streams (SAPS) are formed as the result of magnetosphere-ionosphere coupling processes. These phenomena are associated with region 2 (R2) field aligned currents (FAC) from the inner magnetosphere along with the low-latitude boundary of energetic particle precipitation and low ionospheric conductance in the SAPS flow channel. The fast westward flows can also increase the recombination rate, which further reduces the conductance in the SAPS channel and thus provides a positive feedback. This mechanism increases the SAPS velocity values, or may also even provide a source for SAPS formation.

In this study, we examine SAPS dynamics using observations from multiple sensors including DMSP and Incoherent Scatter Radar (ISR) as well as simulation with the physics-based OpenGGCM-RCM-CTIM model that self-consistently couples the magnetosphere, ionosphere, and thermosphere (MIT). We report on model-observation comparisons to verify simulation validity, along with subsequent numerical experiments to investigate the effect of ionosphere parameters on SAPS morphology. For example, recombination rate modification in the model was done to test whether a positive feedback exists between flows, electron density, and conductance. We will also describe similar experiments with FAC configurations, including elimination of R2 currents to examine whether these currents are a primary driver, or perhaps fringe fields from polar cap convection play a significant role.