An enhanced algorithm for the retrieval of liquid water cloud properties from simultaneous radar and lidar measurements. Part I: The basic analysis of in situ measured drop size spectra

The possibilities to detect and characterize the drizzle fraction in water clouds using the ratio between si- multaneously measured radar reflectivity and optical extinc- tion profiles is presented. An enhanced algorithm for the retrieval of liquid water cloud properties from simultaneous radar and lidar measurements that is based on features of this parameter is described. The study is based on theoretical calculations of remotely measurable quantities from the par- ticle size spectra that were measured with aircraft-mounted in-situ probes during a few field campaigns, in the different geographical regions, and inside the different types of water clouds. Fox and Illingworth, 1997). All these facts give the back- ground for the tries to find the combination of the remotely measurable parameters, which can be used for the detection of drizzle fraction, its parameterization and taking into ac- count in cloud's microphysics retrieval algorithm. In this paper a retrieval technique based on the possibili- ties to characterize drizzle fraction in water clouds using the ratio between simultaneously measured radar reflectivity and optical extinction profiles is presented. This study is based on theoretical calculations of remotely measurable quanti- ties from the particle size spectra that were measured with aircraft-mounted in-situ probes.