TIMED Doppler Interferometer measurements of neutral winds at the mesosphere and lower thermosphere and comparison to meteor radar winds

Abstract

The mesosphere and lower thermosphere (MLT) comprise a highly variable region that forms the transition region between the middle and upper atmosphere. The variability of this region is driven by atmospheric waves transporting energy and momentum from the lower and middle atmosphere to MLT altitudes. These waves cover a wide range of temporal (minutes to days) and spatial (kilometers to planetary) scales. The upward propagation of atmospheric gravity waves and tides is one of the key processes at all latitudes that alters the state of the ionosphere–thermosphere system, and their vertical propagation depends crucially on the background mean winds. The TIMED Doppler Interferometer (TIDI) on board the Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (TIMED) satellite observes neutral winds at the MLT using airglow emissions. We establish a TIDI mean wind climatology, compare our results with existing climatologies derived from local meteor radar observations, and discuss similarities and differences depending on local time and geographical latitude.