Airborne lidar LEANDRE II for water-vapor profiling in the troposphere. II. First results

The airborne lidar LEANDRE II, described in part I [Appl. Opt. 40, 3450-346 1 (2001)], has been flown on the French Atmospheric Research Aircraft to pe rform lower-troposphere (0-3.5-km) measurements of the water-vapor mixing r atio. We present and discuss the method used for retrieval of the water-vap or mixing ratio and analyze systematic and random measurement errors in rel ation to instrument design and performance. The results of a series of test flights are presented. With a 0.8-km horizontal resolution and a 300-m ver tical resolution, the standard deviation of the measurement error ranges fr om approximately 0.05 g kg(-1) at 3.5 km to 0.3-0.4 g kg(-1) near the groun d, in agreement with the predicted random error. Comparisons with dew-point hygrometer measurements show a vertically averaged difference of +/-0.15 g kg(-1), approximately equal to the observed water-vapor variability. (C) 2 001 Optical Society of America.