资源环境科技发展态势分析平台

The Naval Research Laboratory Sami3 is Also a Model of the Ionosphere (SAMI3) ionosphere/plasmasphere code is used to examine the physics of a long-lived plasmasphere plume. The May 1994 storm is simulated. Here a plasma density peak was observed in the afternoon sector by multiple spacecraft at geosynchronous orbit on each of 11 continuous days. The storm is modeled by adding a Kp-driven Volland/Stern-Maynard/Chen analytic convection potential to the self-consistent electric potential that is driven by thermosphere winds. Results are compared to measurements of the cold-ion density from the 1989-046 spacecraft in geosynchronous orbit. We find that many observed features are reproduced by SAMI3 and that high-speed, field-aligned plasma flows from the ionosphere contribute significantly to the plume density.

Plain Language Summary During a storm, a plume forms in the cold, near-Earth plasma known as the plasmasphere. While these plumes have been described as "draining" the plasmasphere, the plasmasphere does not contain enough plasma to supply a long-lasting plume. We investigate the source of the plume plasma in the case where the storm lasts nearly 2 weeks. We show that high-speed flows from the ionosphere, similar to those measured in the "polar wind," supply the plume outflow. The model shows excellent agreement with measurements of a plume during a 12-day storm.