The Development of A New Sensor for Global Thermospheric Wind Measurements From Space

In this paper, we present the concept and the development status of a new-generation neutral wind instrument capable of providing global wind measurements during both day and night from a low earth orbit. Today, detailed quantitative understanding of thermospheric dynamics is still lacking, because of limited observations. Specifically, the key dynamical variables, neutral wind and temperature, have not been measured well with sufficient spatial and local time coverages This instrument, THz Limb Sounder (TLS), is aimed to provide, for the first time, global neutral wind/temperature/density profile measurements, with a focus at altitudes of 100-180 km where most of the ion-neutral energy/momentum couplings take place. It is an ambient-temperature Schottky diode based all solid-state heterodyne spectrometer designed to extend the limb sounding technique employed by Microwave Limb Sounder by measuring the Doppler line shape of atomic oxygen (OI) fine structure emission at 2.06THz. This atomic oxygen line emission is bright and distributed nearly uniformly globally (at all latitudes including high latitude aurora particle precipitation regions) and temporally (at all local times during both day and night), thus ideal for thermospheric remote sensing. The TLS instrument concept, measurement methodology, and its development status will be presented in this paper.