Impacts of Polar Tongues of Ionization and Patches on high-latitude upper thermosphere
Abstract
During geomagnetic disturbances, enhanced magnetospheric convection transports ionospheric plasma from the dayside mid-latitude region into the polar cap, leading to structures such as tongues of ionization (TOIs) and patches. These structures and their effects on M-I-T system are important for both space science research and space weather applications. In this study, we investigate the effects of polar TOIs and patches on high-latitude upper thermosphere, using the two way-coupled high-resolution Magnetosphere-Ionosphere-Thermosphere Model (CMIT), which combines the Lyon-Fedder-Mobarry global magnetosphere model with the NCAR-Thermosphere-Ionosphere Electrodynamic General Circulation Model (TIEGCM). The magnetospheric model in CMIT has a horizontal resolution of 60 km mapped to the ionospheric reference altitude. The thermosphere-ionosphere model in CMIT has a horizontal resolution of 0.625 degrees in both latitude and longitude, which is comparable to the magnetospheric resolution. This three-dimensional, coupled, high-resolution global geospace model is capable of resolving the dynamic evolution of large and meso-scale structures in the polar cap. We focus on the impacts of these TOI and patch structures on F-region thermospheric temperature, density, and winds. The results illustrate that the thermosphere density and winds in the polar cap are impacted significantly by the enhanced F-region Joule heating due to these meso-scale plasma structures. These impacts are relatively independent from those due to the magnetospheric DC Poynting flux as known previously. The study also sheds light upon the underlying physical mechanisms including Joule heating, collisional heating, and ion drag within the dynamic M-I-T system.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSA51A..08D
- Keywords:
-
- 0358 Thermosphere: energy deposition;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 2427 Ionosphere/atmosphere interactions;
- IONOSPHERE;
- 2431 Ionosphere/magnetosphere interactions;
- IONOSPHERE;
- 2437 Ionospheric dynamics;
- IONOSPHERE