Comparison of measured and forecasted water-vapor profilesduring COPS 2007

Abstract

Measurements with the multiwavelength Raman pola-rization lidar BERTHA (Backscatter Extinction lidar Ratio Temperature Humidity profiling Apparatus) have been performed during COPS (Convective Orographi-cally induced Precipitation Study) in the Black Forest, Germany, from June to August 2007. Profiles of the water-vapor mixing ratio from BERTHA are compared with data from radiosonde and an air-borne DIAL (Differential Absorption Lidar) LEANDRE2 onboard the French Safire Falcon). The data of the two lidar systems are in better agreement (average difference of -0.03 g kg-1) than the comparisons of BERTHA and the radiosonde data (average difference smaller than 0.5 g kg-1). The discrepancy between lidar and radiosonde data is attributed to the drift of the radiosonde during its ascent. Raman lidar data are compared with short-range out-puts of the COSMO-DE model (Consortium for small-scale modeling; www.cosmo-model.org) of the Ger-man Weather Service. It is shown that the short-range forecast of water-vapor mixing ratio within the residual layer yields values that are on average 7.9% smaller than the measurement. In the free troposphere pre-dicted values are 9.7% smaller than the measurement