Seasonal Cycle of Gravity Wave Potential Energy Density from Lidar and Satellite Observations at $54^{\circ}$N and $69^{\circ}$N

Abstract

We present the first seasonal cycle of gravity wave potential energy densities from ground-based lidar at high northern latitudes (Andenes/Norway, $69^{\circ}$N, $16^{\circ}$E) and compare with similar observations performed at middle latitudes (K\"uhlungsborn/Germany, $54^{\circ}$N, $12^{\circ}$E). Potential energy densities are derived from lidar temperature profiles observed with high vertical and temporal resolution at these sites. Both lidars have the unique capability of measuring during day and night, covering an altitude range from 30 to about 80 km. For the years 2012-2016 a total of $\sim$ 3000 and $\sim$ 6000 hours of observations were available at Andenes and K\"uhlungsborn, respectively. This data set was used to determine the seasonal variation of mean gravity wave potential energy densities, $E_{pot}$. We have applied wavelength and frequency filtering separately to account for potential influence of large scale waves such as tides. Despite the fact that both locations are rather different in terms of latitude, topography, and mean background conditions, the $E_{pot}$ values at both stations are rather similar, i.e. the monthly means deviate by less than a factor of 2. The mean potential energy densities show a clear seasonal variation at both locations with minimum (maximum) values in summer (winter). However, the winter/summer difference is only a factor of $\sim$ 3. We have compared these lidar results with observations from the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) satellite instrument and find satisfying agreement considering the differences in observational setup.