Gravity waves above the Northern Atlantic and Europe during streamer events using ADM-Aeolus

Abstract. Information about the energy density of gravity waves (GWs) is crucial for improving atmosphere models. So far, most space-based studies report on the potential energy, Epot, of GWs, as temperature measurements from satellite are more common. We used ADM-Aeolus (Atmospheric Dynamics Mission) wind data to derive a lower limit of the kinetic energy density, Ekin, of GWs above the Northern Atlantic and Europe. Aeolus on ADM, ESA’s fourth Earth Explorer Mission, was the first Doppler wind lidar in space and measured vertical profiles of the horizontal line-of-sight wind from the ground to the lower stratosphere (20 – 30 km) between 2018 and 2023. With a vertical resolution of 0.25–2 km, Aeolus measurements are in principle well suited for the analysis of GWs. However, the data quality is a challenge for such analyses, as the accuracy of the data is in the range of typical GW amplitudes in the tropo- and stratosphere. In this study, we derive daily resolved time series of the lower limit of the Ekin, called Ekin,low, before, during and after two so-called streamer events above the Northern Atlantic and Europe. Streamers are large-scale tongue-like structures of meridionally deflected air masses, which are due to enhanced planetary wave activity. They are linked to vertical shear of horizontal wind and a pressure system, two possible GW generation mechanisms. We find that there is a temporal coincidence between the daily averaged Ekin,low and occurrence of the streamer events. The results indicate, that the derivation of GW signals based on Aeolus data is possible. However, we collected about 100 profiles to statistically reduce the uncertainty of the daily averaged Ekin,low. Compared to non-satellite measurements those daily averaged values are at the upper border.