Latent Heat Fluxes over Complex Terrain from Airborne Water Vapour and Wind Lidars

Kurzfassung

Tropospheric profiles of water vapour and wind were measured with a differential absorption lidar (DIAL) and a heterodyne detection Doppler wind lidar collo-cated onboard the DLR Falcon research aircraft in the past two years. The DIAL is a newly developed four-wavelength system operating on three water vapour absorption lines of different strengths, one offline wavelength at 935 nm (each 50 Hz, 40 mJ), and 532 and 1064 nm for aerosol profiling. It is designed as an airborne demonstrator for a possible future space-borne water vapour lidar mission. It operated success-fully during the Convective and Orographically-induced Precipitation Study (COPS) in July 2007 over the Black Forest Mountains in southern Germany, and during the Norwegian THORPEX-IPY field experiment in March 2008 over the European North Sea. For the study of summertime convection initiation over complex terrain and the development of Polar Lows in the North Sea both campaigns included latent heat flux missions where both airborne lidars were pointed nadir-viewing. Using eddy-correlation of the remotely-sensed wind and water vapour fluctuations, a repre-sentative flux profile can be obtained from a single over-flight of the area under investigation. The lidars’ spatial resolution is ~200 m which resolves the domi-nant circulation and flux patterns in a convective boundary layer. This novel instrumentation allows ob-taining profiles of the latent heat flux beneath the air-craft from one single over-flight of any area of interest.