Retrieval of cloud microphysics using 95-GHz cloud radar and microwave radiometer

摘要

Vertical profile of liquid water cloud microphysics is retrieved by a newly proposed algorithm using radar and microwave radiometer. The data used in this algorithm is obtained from a 95-GHz cloud profiling radar (CPR) and a dual-wavelength microwave radiometer. This technique is applicable to liquid water clouds and its products are vertical profiles of attenuation-corrected radar reflectivity factor, liquid water content (LWC), and cloud dropsize distribution. The basic idea of this algorithm is to solve the radar equation with a constraint of integrated liquid water content (LWP: liquid water path) obtained from microwave radiometer. The main features of this algorithm are that it yields an attenuation-corrected radar reflectivity factor and the analytical solution is stable for the attenuation expected in typical stratocumulus clouds. Examples of its application to cloud data observed with a 95GHz CPR and a microwave radiometer at Kashima, Japan on 4 February 2000 are described. The larger cloud drop size than the typical value retrieved and descending motion seen in the clouds examined is explained by the existence of drizzle particles in the lower part of cloud layer.