Gravity Waves and Turbulence indicating multistep vertical coupling near the Polar Vortex Edge

Throughout the winter, extreme circumpolar wind patterns are found in the altitude range of 30 to 70 km, reaching wind speeds up to 500 km/h. The circumpolar wind patterns form the Stratospheric Polar Vortex. In the Northern Hemisphere, weather extremes are known to be linked to distortions of the Polar Vortex. Recently, studies using observations and modelling have indicated that the extreme winds at the Polar Vortex Edge also play a crucial role in multistep upward coupling through gravity waves. Variations in the wind profiles affect gravity wave propagation and lead to wave generation and breakdown. Direct measurements of the mean winds and waves at the Polar Vortex Edge are rare and technically challenging. We use lidar and radar instruments to measure temperature, wind, and the occurrence of layered phenomena over northern Norway (ALOMAR, 69°N) and northern Germany (Kühlungsborn, 54°N). Using more than 10 years of measurements, we have collected a unique dataset, which contains measurements both inside and outside the Polar Vortex.

These observations are used to explore upward- and downward-propagating gravity waves in the complex dynamical setting near the Polar Vortex Edge. These unique wave-vortex interactions play a role in coupling layers above and below, and link large-scale flow to turbulence, frequently observed as layered phenomena, such as Polar Mesosphere Winter Echoes. The link between waves, turbulence, and the polar vortex will be discussed using observations and model data.