Evolutions of a Mesospheric Bore in a Duct Observed by Ground-Based Double Layer Imagers and Satellite Observations Over Tibetan Plateau Region

A strong mesospheric bore event was observed in the airglow layers of both OH and OI (557.7 nm) bands by two all-sky airglow imagers in Lasa (29.66ºN, 90.98ºE) of the Tibetan Plateau on the night of 16-17 December 2014. This event is also caught by the Day Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (NPP) satellite. Simultaneous temperature and OH intensity observations from SABER instrument onboard the TIMED satellite and wind measurement by a Doppler meteor radar are used to characterize the environment of the bore propagation. A large mesospheric inversion layer is identified from the temperature measurements. The observed wind in the height range of the OH layer ( 87 km) is almost orthogonal to the propagation direction of the mesospheric bore. The duct depth variations estimated from the hydraulic jump theory are consistent with the observation. The propagation of bore is strongly modulated by the duct layer. Specifically, the horizontal wavelengths and observed phase speeds of the bore packet decreased as the duct shrinks and increased as the duct expands. The amplitude of the bore packet decreased slowly, and then decreased sharply after dissipates. The present study advances the basic understanding of the dynamic process of gravity waves over Tibetan Plateau region.