Monday, 11 August 2003
The Precipitating Cloud System Studies using UHF Radar/Integrated Sounding System 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. A wide variety of convective systems were observed during SCSMEX and GIMEX. The ISS observations provide a detail kinematic and thermodynamic structure change of the monsoon flow and the boundary layer. 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 for the understanding of the stratiform and the convective characteristics, and the cloud physics and dynamics of the convective systems. The three moments of the Doppler Spectrum provide us with information about the hydrometers in the precipitation systems. Correlations between vertical radial velocity and range corrected signal power of 915 MHz radar wind profiler can be used to determine weather or not precipitation is presentand what type of precipitation it is. Several major convective events occurred in SCSMEX and GIMEX will be discussed and compared in this investigation.
From the 915 MHz profiler radar observation at Dong-Sha Island in SCSMEX we can find the stratiform rain accompanied by a bright band in the equivalent reflectivity and a melting layer signature of rapidly accelerating hydrometeor fall speed below 4.5 km. Some heavier rain episodes illustrate deep convection and a mixture of deep convection with stratiform rain. Correlations between vertical radial velocity and range corrected signal power measured by the vertical pointing beam of 915 MHz radar wind profilers can be used to determine weather or not precipitation is present and what type of precipitation it is. Based on the S-V correlation diagram analysis, four major groupings of points can be identified including four representing conditions dominated by scattering from either air, rain, ice and melting ice. The Characteristics of this classificatio
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