This research continues exploring ionospheric dynamics and composition by utilizing computer models embodying relevant physics and applying observations as constraints and boundary conditions. The relative composition of O+, H+ and He+ in the low and middle latitude topside ionosphere depends on solar activity, season, local time, latitude and the daily variability of ExB drifts and neutral winds in the F-region. The PI will determine the sensitivity of all these parameters to successfully interpret data from satellites and recently upgraded radars. He will use a newly improved ionosphere model, including a realistic magnetic field geometry, to perform these studies and compare results with observations from satellites and ground-based radars. Observations of depleted plasma regions at low latitudes show so-called 'bubbles' moving upward to very high altitudes. Motion of these depleted regions depends on the flux tube integrated conductivity, which depends on the redistribution of the plasma along the magnetic flux tube taking place as a result of its upward motion. To further understand the large scale dynamics of plasma bubbles, the PI will employ a single flux tube model of the ionosphere to incorporate drift dependent on the spatial variations in the flux tube integrated conductivity.
