Characteristics of the raindrop size distribution and drop shape relation in typhoon systems in the western pacific from the 2D video disdrometer and NCU C-band polarimetric radar

Wei Yu Chang, Tai Chi Chen Wang, Pay Liam Lin

研究成果: 雜誌貢獻期刊論文同行評審

102 引文 斯高帕斯(Scopus)

摘要

The drop size distribution (DSD) and drop shape relation (DSR) characteristics that were observed by a ground-based 2D video disdrometer and retrieved from a C-band polarimetric radar in the typhoon systems during landfall in the western Pacific, near northern Taiwan, were analyzed. The evolution of the DSD and its relation with the vertical development of the reflectivity of two rainband cases are fully illustrated. Three different types of precipitation systems were classified-weak stratiform, stratiform, and convective-according to characteristics of the mass-weighted diameter Dm, the maximum diameter, and the vertical structure of reflectivity. Further study of the relationship between the height H of the 15-dBZ contour of the vertical reflectivity profile, surface reflectivity Z, and the mass-weighted diameter Dm showed that Dm increased with a corresponding increase in the system depth H and reflectivity Z. An analysis of DSDs retrieved from the National Central University (NCU) C-band polarimetric radar and disdrometer in typhoon cases indicates that the DSDs from the typhoon systems on the ocean were mainly a maritime convective type. However, the DSDs collected over land tended to uniquely locate in between the continental and maritime clusters. The average mass-weighted diameter Dm was about 2 mm and the average logarithmic normalized intercept Nw was about 3.8 log10 mm-1 m-3 in typhoon cases. The unique terraininfluenced deep convective systems embedded in typhoons in northern Taiwan might be the reason for these characteristics. The "effective DSR" of typhoon systems had an axis ratio similar to that found by E. A. Brandes et al. when the raindrops were less than 1.5 mm. Nevertheless, the axis ratio tended to be more spherical with drops greater than 1.5 mm and under higher horizontal winds (maximum wind speed less than 8 ms-1). A fourthorder fitting DSR was derived for typhoon systems and the value was also very close to the estimated DSR from the polarimetric measurements in Typhoon Saomai (2006).

原文???core.languages.en_GB???
頁(從 - 到)1973-1993
頁數21
期刊Journal of Atmospheric and Oceanic Technology
26
發行號10
DOIs
出版狀態已出版 - 10月 2009

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