Atmospheric Gravity Waves Observed in the Nightglow Following the 21 August 2017 Total Solar Eclipse

Nighttime airglow images observed at the low-latitude site of Sao Joao do Cariri (7.4 degrees S, 36.5 degrees W) showed the presence of a medium-scale atmospheric gravity wave (AGW) associated with the 21 August 2017 total solar eclipse. The AGW had a horizontal wavelength of similar to 1,618 km, observed period of similar to 152 min, and propagation direction of similar to 200 degrees clockwise from the north. The spectral characteristics of this wave are in good agreement with theoretical predictions for waves generated by eclipses. Additionally, the wave was reverse ray-traced, and the results show its path crossing the Moon's shadow of the total solar eclipse in the tropical North Atlantic ocean at stratospheric altitudes. Investigation about potential driving sources for this wave indicates the total solar eclipse as the most likely candidate. The optical measurements were part of an observational campaign carried out to detect the impact of the August 21 eclipse in the atmosphere at low latitudes.