McMurdo Lidar observations of Vertical Winds, Temperatures, and Metal Layers before, during, and after the 2019 Antarctic SSW

Abstract:

Research in recent decades has found globally widespread effects of sudden stratospheric warmings (SSWs) on terrestrial weather, space weather, atmospheric chemistry, satellite navigation systems, and telecommunications. Indeed, SSW impacts are visible from the surface to the thermosphere and ionosphere, and from the polar to the equatorial regions. SSWs occur an order of magnitude more often in the Northern Hemisphere (NH) and major SSWs are extremely rare in the Southern Hemisphere (SH), with the only known major SSW in September 2002. The strongest minor Antarctic SSW on record occurred in September 2019 and the temperature changes associated with it and the impacts on various atmospheric parameters are much larger than during the SSW 2002.

With advanced resonance-fluorescence Boltzmann and Doppler lidar technologies, the University of Colorado lidar group has been making lidar measurements covering a large altitude range from the stratosphere to the thermosphere for nearly a decade at McMurdo (77.84S, 166.67E), Antarctica. Our observations caught the SSW event in September 2019, and provided data for multi-dimensional examinations of SSW impacts on the atmospheric thermal structure, vertical winds, meteoric metal species, polar stratospheric clouds, and gravity waves. To our knowledge, this is the first SSW event ever observed by lidars at McMurdo, so it provides a unique opportunity to study SSW impacts over Antarctica.

In this paper we report how the Antarctic stratosphere, mesosphere and thermosphere respond to the rare SSW event. In particular, we show the first lidar observations of changes in vertical winds, temperatures, and metal layers during the 2019 SSW in Antarctica. Furthermore, MERRA-2 and MLS data are used to provide a global context for the single lidar station, i.e., how the vertically-pointing lidar first samples inside the polar vortex core, then samples the vortex jet region, and finally samples inside the anticyclone core. High-resolution general circulation model simulations are used to advance understanding of the mechanisms whereby the lower atmosphere is coupled to the thermosphere.