162 ACTA METEOROLOGICA SINICA VOL.22 Application of Radar Re ectivity Factor in Initializing Cloud-Resolving Mesoscale Model. Part I: Retrieval of Microphysical Elements and Vertical Velocity

Assuming that cloud reaches static state in the warm microphysical processes, water vapor mixing ratio (qv), cloud water mixing ratio (qc), and vertical velocity (w) can be calculated from rain water mixing ratio (qr). Through relation of Z-qr, qr can be retrieved by radar re ectivity factor (Z). Retrieval results indicate that the distributions of mixing ratios of vapor, cloud, rain, and vertical velocity are consistent with radar images, and the three-dimensional spatial structure of the convective cloud is presented. Treating qv saturated at the echo area, the retrieved qr is about 0.1 g kg 1, qc is always less than 0.3 g kg 1, w is usually below 0.5 m s1, and rain droplet terminal velocity (vr) is around 5.0 m s 1 in the place where radar re ectivity factor is about 25 dBz; in the place where echo is 45 dBz, the retrieved qr and qc are always about 3.0 g kg1, w is greater than 5.0 m s1, and vr is around 7.0 m s 1. In the vertical, the maximum updraft velocity is greater than 3.0 m s1 at the height of around 5.0 km, the maximum cloud water content is about 3.0 g kg1 above 5 km and the maximum rain water content is about 3.0 g kg1 below 6 km. Due to the assumption that the cloud is in static state, there will be some errors in the retrieved variables within the clouds which are rapidly growing or dying-out, and in such cases, more sophisticated radar data control technique will help to improve the retrieval results. Key words: radar, hydrometeors, nowcasting, cloud-resolving model 1