Joint observation of the concentric gravity wave event on the Tibetan Plateau

A concentric gravity wave event was captured by a photographer in Nagarzê County (90.28°N, 28.33°E) between 02:00 and 04:00 (local time) on May 11, 2019. This concentric gravity wave event was also observed by the Suomi National Polar-orbiting Partnership satellite and the all-sky airglow imager at Yangbajing station (90.5°E, 30.1°N). The temporal and spatial information on gravity waves from the photographs provided a rare opportunity to study the propagation of gravity waves over the Tibetan Plateau. According to wind and temperature data from the MERRA-2 reanalysis (Modern-Era Retrospective analysis for Research and Applications, Version 2) and empirical models (NRLMSISE-00 Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar Exosphere and HWM horizontal wind model), we inversely derived the propagation trajectory from the observed wave pattern to the source region by using the ray-tracing method. The source of the concentric gravity wave was identified as deep convection in Bangladesh (90.6°E, 25.0°N). The maximum background wind speed in the propagation direction (31.05 m/s) was less than the phase speed of 53 m/s, which is consistent with the wind-filtering theory.