Particle size retrieval in cirrus clouds by use of a multiple scattering Raman LIDAR technique

Cirrus clouds have a strong influence on the radiation field of the Earth-atmosphere system. To quantify this impact, more accurate studies of their physical properties are required. In this work we present a Raman LIDAR technique that computes a correction to the multiple scattering influence on the detected signal and retrieves the layer mean diffraction-equivalent particle size in cirrus clouds. Particle size retrievals, using an updated approach to what we have published previously [1], are performed using Scanning Raman LIDAR (SRL) data acquired in September 1997. These retrievals are compared with passive ones from ground-based IR interferometer and show good agreement. A sensitivity study has been performed as a part of an assessment of the uncertainty in the particle size retrievals. The attractiveness of the particle size retrievals presented here is that they take advantage of information that is available in the typical Raman LIDAR measurement of cirrus clouds that is usually ignored in data analysis. This work is being carried out by the author as part of her PhD studies in Atmospheric Physics at the University of Maryland, Baltimore County.