OH airglow imaging observations of a mesoscale gravity wave generated by jet streams near the Tibetan Plateau region

This study investigates the source and dynamics of a mesoscale gravity wave (MGW) observed over northern China. On 12 January 2010, an OH airglow imager at Xinglong station (40.2°N, 117.4°E) detected an MGW propagating from southwest to northeast, consistent with background wind direction. The wave exhibited a horizontal wavelength of 125 ± 7.6 km, an observed period of 25 ± 3.2 min, and a phase speed of 83 ± 12.4 m/s. The momentum flux and the energy flux of the MGW were approximately 24.93 m2/s2 and 1.08×10-5 W/m2 from airglow imaging observation, respectively. During propagation, wave breaking generated secondary ripples with wavelengths of 5–12 km. These ripples were likely caused by wind shear, as measured by the Doppler meteor radar at Shisanling (40.3°N, 116.2°E). According to OH emission profiles from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite, the height of the OH airglow layer is ~81 km during the MGW propagation event. A separate northwestward-propagating small-scale gravity wave with a wavelength of ~35 km was also observed. The backward ray-tracing analysis conducted with the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis data indicates that the jet system near the Tibet Plateau served as the source for the MGW.