Airborne coherent wind lidar measurements of the momentum flux profile from orographically induced gravity waves

Abstract. In the course of GW-LCYCLE II campaign, conducted in Jan/Feb 2016 from Kiruna, Sweden, coherent Doppler wind lidar (2 µm DWL) measurements were performed DLR Falcon aircraft to investigate gravity waves induced by flow across Scandinavian Alps. During a mountain wave event on 28 January 2016, novel momentum flux (MF) scan pattern with fore and aft propagating laser beams was applied 2 DWL. This allows us measure vertical horizontal along flight track simultaneously high resolution ≈800 m hence enables derive MF profile for broad wavelength spectrum few hundred meters several kilometers. The functionality this method corresponding retrieval algorithm is validated using comparison against situ data measured High Altitude Long Range (HALO) which also deployed Kiruna POLSTRACC (Polar Stratosphere Changing Climate) campaign. Based that, systematic random error speeds retrieved DWL observations are determined. Further, that day used reveal significant changes wavelengths speed leg-averaged fluxes tropopause inversion layer (TIL) region, likely be interfacial as recently presented Gisinger et al. (2020).