Model Simulation of Plasma Flow in the Topside Ionosphere

Global distribution and seasonal variation of plasma flow in the topside ionosphere is fundamental to the maintenance of the F-region ionosphere. Generally, the plasma flows upward in the daytime from the ionosphere into the plasmasphere and flows downward in the nighttime from the plasmasphere to the ionosphere. However, the flow changes dramatically with local-time, season, latitude and height. In many of the models that calculate the ionosphere and thermosphere self-consistently, values of plasma fluxes are specified at the upper boundary. Therefore, to understand the longitudinal and local-time variation of plasma fluxes in the topside ionosphere is important for improving the upper boundary condition in these models. The Global Ionosphere and Plasmasphere model (GIP) consists of a low- and mid-latitude region where interhemispheric transport along closed flux tubes is taken into account, and a high-latitude portion, which has a fixed upper boundary at 10,000 km. Using the GIP model, the plasma density and velocity along the flux tubes are calculated. This study provides the height/longitudinal/latitudinal distributions of plasma fluxes simulated by the GIP under different seasons and solar activity conditions. Also, the causes of variability in plasma flow are investigated through changing the model parameters (e.g. magnetic coordinates), thermospheric winds, and different parameterizations (e.g. electron temperature calculation).