Wave Activity in Thermospheric Vertical Winds and Temperatures at Subauroral Latitudes

The need for high precision measurements of vertical winds with uncertainties less than 3-5 m/s and a temporal cadence of 1-2 min has made it exceedingly difficult to study the response of the thermosphere to gravity wave activity.  Herein we present subauroral, midlatitude thermospheric wave measurements of 630 nm OI emission from a 15 cm narrow field Fabry Perot Interferometer, named the Hot Oxygen Doppler Imager (HODI).  These measurements of temperature and vertical wind velocities are from a first light campaign at Jenny Jump Observatory (40.9 N, 74.9 W) located in northwestern New Jersey. The heightened sensitivity of HODI enables analysis of gravity wave behavior with uncertainties of 3-5 m/s for vertical wind speeds and 10-15 K for temperatures for two-minute exposures. Data was collected during periods of geomagnetically quiet and active conditions, and apparent wave structures were seen during both conditions.  One detailed observation, taken the night of July 25, 2022, enabled the ~90-deg phase shift between vertical winds and temperatures to be inferred, as per standard gravity wave polarization relations with viscous dissipation.  However, most other observations found to have little correlation between the temperature and vertical winds, which we speculate may be a result of the propagation and interaction of multiple wave events. Traveling ionospheric disturbances (TIDs) are often described as the ionospheric signature of the passage of gravity waves, and we provide comparisons of select wave events to medium scale TIDs using differential total electron count (TEC) maps.