Sub-Auroral Polarization Stream (SAPS) Events Under Non-storm Conditions
Abstract
The occurrence of Sub-Auroral Polarization Stream, or SAPS, structures, defined here as latitudinally narrow channels of enhanced westward plasma convection in the evening ionosphere equatorward of the auroral electron precipitation boundary, is most dramatic during geomagnetic storms. However, SAPS-like structures known as Polarization Jets or SAIDs (Sub-Auroral Ion Drift events) are also frequently observed during non-storm conditions, typically during periods of isolated substorm activity or during bursts of enhanced convection associated with southward IMF Bz component. This paper presents results from data analysis and numerical simulations of several SAPS/SAID events observed during non-storm conditions. We use convection velocity measurements from the mid-latitude chain of SuperDARN radars and cross-track drift meter data from DMSP spacecraft to identify SAPS/SAID and to characterize their structure and temporal evolution. DMSP topside ion density data and high-resolution ground-based GPS total electron content (TEC) maps are used to determine the ionospheric and plasmaspheric morphology of SAPS regions. DMSP electron precipitation data are used to determine auroral boundaries. We also present simulation results of the chosen event intervals obtained with the SAMI3-RCM ionosphere-magnetosphere coupled model. Observational results are analyzed to identify systematic differences between non-storm SAPS/SAID and the picture that has emerged based on previous storm time studies. Simulation results are used to provide physical interpretation of these differences.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMSA41C..07S
- Keywords:
-
- 2411 Electric fields;
- IONOSPHERE;
- 2431 Ionosphere/magnetosphere interactions;
- IONOSPHERE;
- 2463 Plasma convection;
- IONOSPHERE;
- 2788 Magnetic storms and substorms;
- MAGNETOSPHERIC PHYSICS