Observation of Thermospheric Gravity Waves in the Southern Hemisphere With GOLD

The middle thermosphere from ~150 to 250 km is characterized by rapid increase in temperature with altitude and rapid ionization. The entire thermosphere is believed to be home to atmospheric waves that propagate through it, originating both in the atmospheric layers below and in the thermosphere itself. Within the middle thermosphere, direct observations of such waves are extremely sparse. The Global-scale Observations of the Limb and Disk (GOLD) far-ultraviolet imaging spectrometer is able to observe the middle thermosphere from geostationary orbit. During October 2018, a special observational campaign was performed, designed to identify atmospheric waves. Signatures in the 135.6-nm O airglow were seen that move northward with time, away from the southern polar region. These are consistent with a large-scale atmospheric gravity wave. These results are the first time 135.6-nm airglow has been used to track such a wave and highlight the ability of GOLD to observe such waves, even when at a modest amplitude, and track their motion.