Thermospheric Neutral Composition Response to External Forcings

The major constituents in the thermosphere are atomic oxygen (O) and molecular nitrogen (N2). These constituents diffusively separate according to their scale heights, such that the heavier species are concentrated at lower altitudes, while the light ones dominate higher up. Their structure is controlled by the global circulation, which in turn is very dependent on the balance between solar heating, magnetospheric forcing, and lower atmospheric waves that propagate upwards into the upper atmosphere. Previous studies have shown that the O/N2 ratio is an excellent parameter to describe the morphology of thermospheric composition changes with respect to season, latitude, local time, and level of magnetic activity. In this study, the physics-based Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics (CTIPe) and the Whole Atmosphere Model (WAM) models will be used along O/N2 satellite observations to investigate the model response to changes in composition resulting from various external forcings.