Measured vertical motion and converging and diverging horizontal flow of the midlatitude thermosphere

Abstract

Interferometric measurements of nightglow 630.0 nm doppler shifts and widths have yielded determinations of the meridional, zonal and vertical velocities and the temperature in the midlatitude thermosphere during the Priority Regular World Day 18 May 1983. Both the meridional and zonal velocities exhibit a diverging flow in the early night, changing to a converging flow in the later night. Associated with this are apparent, large vertical velocities (20‐30 m/s), upward in the early night, downward in the later night and back upward at the end, which also correlate with decreases and increases in the neutral temperature. While the sense of these observed effects is in agreement with the behavior predicted by existing hydrodynamic models of thermospheric flow, the magnitudes are either much larger (vertical velocities) or much smaller (temperature changes) than the model predictions.