Direct Observation of Quasi-Monochromatic Gravity Wave Packets Associated With the Polar Night Jet Using a Doppler-Rayleigh Lidar

Abstract

An advanced hodograph technique was applied to extract quasi-monochromatic, linear gravity wave (GW) packets from simultaneous wind and temperature measurements made using a ground-based Doppler-Rayleigh-Mie-Raman lidar located in Kühlungsborn (54°N, 12°E). During the night of 11–12 February 2022, the stratospheric polar vortex was slightly elongated toward Central Europe. The polar night jet's (PNJ) core was located nearly above the lidar. This unique meteorological situation allowed the measurement of horizontal wind and temperature in a stratospheric high-wind speed regime. GW propagation in the strong vertical gradient of the horizontal winds associated with the PNJ was observed. In addition, the subsequent reduction in the number of upward and downward propagating GWs in the strong winds of the PNJ was demonstrated. A pair of upward and downward propagating GWs at the top and bottom edge of the PNJ's core could be the result of shear excitation in the PNJ. A statistical analysis of intrinsic GW parameters is provided for all resolved linear GWs. Approximately 35% of the resolved GWs propagate downward, and there is stronger filtering of the downward waves compared to the upward waves in the PNJ core. ECMWF-IFS horizontal winds and temperatures had a lower variability than the lidar measurement and a poorer overall agreement above 50 km. Stratospheric temperatures in ECMWF show a cool bias of greater than 2 K.