Relative Humidity, Backscattering Ratio and Depolarization Ratio as Derived from Raman Lidar Observations

Abstract

Simultaneous observation of the vertical profiles of tropospheric water vapor and the density and nonsphericity of aerosol particles was made with a Raman lidar at Nagoya (35°N, 137°E). The data from observations made on April 17, 1994 showed the following features of the water vapor and aerosol particles. Temporal and systematic variations of the parameters were observed at the lower altitude range of 1.0-2.2km, where the mixing ratio of aerosol particles (backscattering ratio) increased and the nonsphericity of the particles (depolarization ratio) decreased with increasing humidity. There was a positive correlation between the vertical profiles of backscattering ratio and the water vapor mixing ratio. The depolarization ratio was positively correlated with the water vapor mixing ratio above 2.2km and negatively correlated below this level. The altitudes where the discontinuities of the water vapor and aerosol parameters were found and that where the correlation between the depolarization ratio and the water vapor mixing ratio changed showed the correspondences with the temperature inversion or wind shears observed at Hamamatsu (35°N, 138°E).