Backscatter Lidar Observation of the Aerosol Stratification over Rhine Valley during a 'hot-wave' in September 1999

摘要

A backscatter lidar study of the aerosol stratification in PBL over the Rhine valley is presented in this work. The observations have been made from 6 till 14 September 1999 in the Special Observation Period of the Mesoscale Alpine Program at the site of Trubbach, Switzerland (47°04' N, 9°28' E, 490 m above sea level (asl)). The lidar was operated alongside with a wind-temperature radar, a set of surface meteorological stations and radiosonde observations. The atmospheric conditions for the presented measurements are especially favourable for development of convective PBL. A daily series of range-corrected lidar signal and its gradient are given, showing the diurnal cycle of aerosol layers development in the PBL and lower troposphere over the valley. Averaged altitude distributions of the aerosol backscatter coefficient and the lidar signal gradient are presented and discussed. The results show that the aerosol distribution below the surrounding mountain peaks (approximately 2200-2400 m asl) have the diurnal pattern as following from the thermal wind cycle and the temperature inversions in the valley and is characterized by a highly dynamic aerosol stratification. Above this level, we observe a diurnally less variable stratification till latitudes of the highest Alpine peaks (approximately 4500-5000m asl).