Observing Gravity Wave Coupling and Day-to-Day Variability Over the Polar Vortex During the 2018-2019 Winter Season

Gravity Waves (GWs) are influential drivers of Earth’s atmospheric dynamics, and lower drivers can impact the dynamics seen in the upper atmosphere, such as the thermosphere. These dynamics include perturbing background winds, temperatures and densities, and the deposition of momentum, which results in drag on background mean winds. GW activity is dampened during atmospheric events called Sudden Stratospheric Warmings (SSW), which is a sudden increase in stratospheric temperatures that occurs in the winter hemisphere and affects high latitude regions known as the polar vortex. This work investigates GW day-to-day variability over the 2018-2019 northern hemisphere winter, during which an SSW occurred in early January. It will also explore how day-to-day variability relates to coupling from the stratosphere to the thermosphere. The Atmospheric InfraRed Sounder (AIRS) temperature variance data is used to calculate average stratospheric daily variances over multiple local regions within the polar vortex: Alaska, Europe and North East Russia, over the course of the 2018-2019 winter season. This stratospheric behavior is compared to thermospheric/ionospheric Medium Scale Traveling Atmospheric/Ionospheric Disturbance (MSTAD/MSTID) power indices calculated for the same season over Alaska using data from a Scanning Doppler Imager and SuperDarn radar. Areas within the polar vortex experience similar diminished wave activity due to the SSW, such as wave activity being dampened, however, they do not all behave uniformly throughout the season. By using these data sets, localized effects of global phenomena, such as the major SSW, are studied.