Gravity Wave, Planetary Wave, and Tidal Activity in the Arctic Stratosphere and Mesosphere in Winter 2018-2019 and Winter 2019-2020

We investigate the interaction of waves and the atmospheric circulation in the Arctic during the winters of 2018-2019 and 2019-2020. We base our investigation on three elements using a combination of ground-based and satellite measurements. These are: 1) observations of wave activity in the upper stratosphere-lower mesosphere (USLM, 40-50 km) and the upper mesosphere-lower thermosphere (UMLT, 80-100 km); 2) mean winds and tides in the UMLT; and 3) planetary waves in the stratosphere and mesosphere. The ground-based observations were made with a Rayleigh density temperature lidar, a sodium resonance wind-temperature lidar, and a meteor wind radar collocated at Poker Flat Research Range, Chatanika, Alaska (65°N, 147°W). The satellite measurements are made with TIMED-SABER and Aqua-AIRS. Multi-year observations have shown strong modulation of gravity wave activity in the USLM associated with Sudden Stratospheric Warmings (SSWs). In January 2019 there was a major SSW with a disruption of the wintertime circulation and splitting of the polar vortex. In 2019-2020 no SSW occurred. We extend previous studies by investigating the behavior of gravity wave activity in both the USLM and UMLT and relationships to the mean winds, tides, and planetary waves. We investigate the vertical coupling between these two regions before, during, and after the SSW. We consider the role of primary and secondary gravity waves in this coupling.