Ionosphere-thermosphere coupling at high latitudes

The high-latitude upper atmosphere is a key region where the major part of the solar wind energy input is transferred and dissipated. This presentation will show recent observations on the thermospheric responses during space weather events and discuss the coupling processes in the high-latitude ionosphere-thermosphere system. We focus on disturbances in the neutral winds and neutral mass density in the upper thermosphere during substorms and storms. Multi-scale wind disturbances are found to be associated with substorm and auroral activity, as well as polar cap patches. Significant neutral wind, neutral mass density, and composition changes are observed during magnetic storms. Those results suggest that the high-latitude thermosphere is highly dynamic in contrast to the previous point of view that it is a passive, slowly changing medium.