[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-12] Dependence of High-Latitude Ionosphere-Thermosphere Coupling on Geomagnetic Activity

*Katherine Davidson¹、Ying Zou²、Mark Conde³、Asti Bhatt⁴ (1.University of Alabama in Huntsville、2.Johns Hopkins Applied Physics Laboratory、3.University of Alaska Fairbanks、4.SRI International)

High-latitude ionospheric convection is driven by electromagnetic coupling between the magnetic field and solar wind, and therefore rapidly responds to changes in geomagnetic activity. F-region thermospheric winds, however, have drivers of both solar and magnetospheric origins, and therefore do not experience a direct response to changes in solar wind conditions. Thermospheric winds generally follow changes in ionospheric convection via the ion-drag force, but will experience a lag in their response, with response times in the range of tens of minutes to hours. The response time of the neutral winds is directly related to the strength of ion-neutral coupling, and its dependence on geomagnetic activity levels is not well understood. Therefore, we perform a statistical analysis of neutral wind response times compared to various geomagnetic indices. We use a newly developed weighted windowed time-lagged correlation (Weighted WTLC) technique on horizontal plasma flow and neutral wind vectors from the Poker Flat Incoherent Scatter Radar (PFISR) and Scanning Doppler Imagers (SDIs), respectively, to calculate neutral wind response times. These response times are then binned according to various global and local geomagnetic indices, such as the AE index, ground magnetometer perturbations from the THEMIS ground observatory, and electron density data from PFISR. Correlations between the neutral wind response time and geomagnetic indices will help develop an understanding of ionosphere-thermosphere couping’s dependence on geomagnetic activity.