A Study of the Diurnal Tide in the MLT Region During the 2020 Sudden Stratospheric Warming Over Yinchuan, China (38.8°N, 106.8°E)

Abstract

We present a study of diurnal tidal variations in the mesosphere and lower thermosphere (MLT) region over Yinchuan (38.8°N, 106.8°E) during the 2020 Northern Hemisphere winter sudden stratospheric warming (SSW) event. This research utilizes data from a newly established meteor radar at Yinchuan, in conjunction with the Specified Dynamics Whole Atmosphere Community Climate Model with Thermosphere and Ionosphere Extension (SD-WACCM-X), the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) reanalysis data, and a meteor radar in Beijing, China (40.3°N, 116.2°E). Our analysis reveals a significant enhancement in the amplitude of the diurnal tide during the 2020 SSW in both meridional and zonal wind components, exceeding the climatological mean by two standard deviations. The variation in the ratio of absolute vorticity to planetary vorticity in the MLT region is known to correlate with diurnal tide amplitude. Our findings indicate that the zonal-mean zonal wind in the MLT underwent a dramatic change during the SSW, with the ratio beginning to decrease 2 days prior to the event. This suggests that changes in the zonal-mean zonal wind during the SSW may play a crucial role in the observed amplification of the diurnal tidal amplitudes. Nevertheless, further investigations are needed to better understand the amplification of diurnal tides in the MLT region during SSWs.