Seasonal variation of gravity wave activity at midlatitudes from 7years of COSMIC GPS and Rayleigh lidar temperature observations

Seven year series of gravity wave (GW) potential energy at midlatitude stratosphere (10 to 50km) is constructed by combining temperature profiles provided by Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) GPS satellite constellation and Rayleigh lidar operating at Haute Provence observatory in Southern France. The combined series are used to evaluate the representation of GW in Modern Era Retrospective-Analysis for Research and Applications reanalysis. The seasonal and zonal variabilities of GW activity are diagnosed using zonal wind and wind divergence provided by ERA-Interim reanalysis. The spatiotemporal distribution of GW activity is found strongly dependent on the zonal wind variation, wind divergence, and topography. We show that anomalies in the wind divergence can serve as a proxy for locating synoptic-scale enhancements of GW. The analysis provides evidence for orographic GW excitation, and the results are compatible with geostrophic adjustment being an additional source of stratospheric GW. The seasonal GW variability can be largely explained by interaction with the mean flow and wave propagation. Key Points * Synergetic use of different observation techniques for studying gravity waves * Gravity wave activity distribution is set by the wave-mean flow interactions * Wind divergence can be used as a proxy for locating gravity wave hot spots