Thermospheric Wind Fields Above EISCAT-3D, Derived Using Ground-Based Tristatic Optical Doppler Spectroscopy

We present observations of vector wind fields measured at E- and F-region heights in the thermosphere, across a region encompassing the EISCAT-3D field of regard above northern Scandinavia. Ground-based Scanning Doppler Imager instruments located at three sites in Finland and Sweden each viewed the overhead night sky in monochromatic (558 nm or 630 nm ) light down to roughly 20 degrees above the horizon. These images were divided (in software) into 115 independent look directions for each site, and optical Doppler spectroscopy was used to derive estimates of the line-of-sight (LOS) wind component seen in each direction. By combining the 558 nm and 630 nm LOS wind measurements from the three sites, were have generated estimates of the full three-component (zonal, meridional, vertical) wind vector, resolved over four measurement dimensions (latitude, longitude, altitude, and time). These data were supplemented by dedicated high-fidelity vertical wind measurements taken at each site using a second Doppler spectrometer viewing solely in the zenith direction. Here we present several examples of the resulting wind fields, and discuss the potential for combining data from this facility with that from EISCAT-3D, for synergistic studies of space weather impacts on the auroral thermosphere.