Precipitation and Boundary Layer Studies Using UHF Radar /ISS, Disdrometer and Weather Radar in Taiwan

The NCU(National Central University) ISS(Integrated Sounding System) was deployed in Dongsha island during May 5 to June 25, 1998 for the SCSMEX and deployed in the southeastern coast of Taiwan(Cheng-Kung station) during May 5 to June 30,2001 for the GIMEX. It was also deployed in the southern part of Taiwan in the past three years' fall seasons for air pollution meteorology observation. The primary goal of these deployments were to measure the mesoscale structure of convective weather system and detail kinematic and thermodynamic structure change of the monsoon boundary layer flow and the local circulations. The detail boundary layer structure associated with several major convective events and severe air pollution episods will be discussed and compared in this investigation. The UHF profiler radar that operates at 915 MHz in ISS are useful for precipitation structure measurement because of its sensitivity to hydrometers. The identification and classification of the falling particles associated with precipitation is very helpful to understand the characteristics of stratiform and convective precipitation. The three moments of the Doppler Spectrum provide us with information about the hydrometers in the mesoscale convective systems. Correlations between vertical radial velocity and range corrected signal power of 915 MHz radar wind profiler can be used to determine weather precipitation is present or not and what type it is. The disdrometer, raingauge network and Doppler radar data were collected since 2002 in Taiwan. Simultaneous observations made with optical-and impact-type disdrometers were analyzed. Drop size distribution(DSDs) of the different precipitation systems were compared and discuss. The Gamma drop size distributions are derived from disdrometer observation at six minutes interval. The Z-R relations through Gamma distribution are calculate The rainfall estimate from the disdrometer derived Z-R relations will be compared with the raingauge observations.