Airborne Wind and Water Vapor Lidar Measurements during ETReC 2007

Kurzfassung

In summer 2007, the European THORPEX Regional Campaign (ETReC 2007) took place over Western Europe. The field experiment was coordinated with the International Convective and Orographically-Induced Precipitation Study (COPS). ETReC 2007 aimed on the predictability of summertime convection. ETReC 2007 provided additional upstream measurements to complement the regional observations in the Vogues Mountains and the Black Forest during COPS. Using five sets of sensitive area forecasts, six upstream aircraft missions were realized with the DLR research aircraft Falcon, equipped with lidar instruments and a dropsonde system. Further observations were obtained from AMDAR measurements and additional radiosoundings, provided by EUCOS. Onboard the DLR Falcon, tropospheric profiles of water vapour and wind were measured with the differential absorption lidar (DIAL) and a wind lidar. The new DIAL system operated successfully on three wavelengths (two onlines, one offline at each 50 Hz, 40 mJ) around 935 nm, plus 532 and 1064 nm for aerosol characterisation. With either nadir-viewing or conical scans, the wind lidar observed the wind field below the aircraft. The observed high-resolution wind and water vapor fields have been analysed, quality checked and compared with one hourly output of specially performed short-term forecast runs of the ECMWF's Integrated Forecast System (IFS). The results will be presented and discussed. Additionally, Lagrangian backward trajectories were calculated to determine the parcel’s pathways and the origin of the observed air masses. The measurements of water vapor and wind velocity were used to evaluate the global model forecasts. The main part of this presentation investigates the tropospheric water vapor transport in a pre-convective environment by means of simultaneous and co-located lidar observations. With our newly developed technique we are able to provide a valuable validation of a key component of the moisture budget.