Coincident thermospheric wind measurements using ground-based Doppler Asymmetric Spatial Heterodyne (DASH) and Fabry–Perot Interferometer (FPI) instruments

Abstract

The thermospheric wind is a critical geophysical parameter for understanding the behavior of the Earth's upper atmosphere. Global-scale characterization of this parameter is needed to enable improved specification and forecasting of the near space environment. Global-scale measurements of horizontal wind vectors versus altitude have been performed from satellites using a variety of techniques, but the available data are still sparse. To address some of the challenges presented by space-based thermospheric wind measurement, the Doppler Asymmetric Spatial Heterodyne (DASH) technique has recently been developed. Here we present results of a ground-based validation of the DASH technique. The successful validation was performed by conducting collocated ground-based measurements with an instrument that uses the well established Fabry–Perot interferometer technique. Due to cloud cover and a limited observation period, data for only one night of simultaneous observations with minor cloud interference were obtained. The wind velocities observed by the two techniques show good overall agreement, but differences larger than the combined uncertainties are present at times. Contributions to these larger disagreements could be due to cloud interference, the minor differences in the observation geometry, or a non-zero vertical wind. A comparison of this single night of data with the Horizontal Wind Model (HWM07) climatology shows differences of up to about 100m/s on timescales of less than an hour to several hours.