Classification of rain types using drop size distributions and polarimetric radar: Case study of a 2014 flooding event in Korea

Abstract

To classify precipitation types as either convective or stratiform, drop size distributions (DSDs) measured by the Parsivel (PARticle size VELocity) instrument, and DSD parameters including median volume diameter (D0) and normalized number concentration (Nw) retrieved by S-band polarimetric radar (BSL), were analyzed for a heavy rainfall event that occurred in southern Korea on 25 August 2014. The rainfall system was clearly identified as stratiform or convective rain at various times of day, at measurement sites at Changwon and Busan. New rainfall classification lines were derived from the Parsivel and BSL data, and were compared with existing classification methods based on climatological rainfall data.The classification methods using logNw-D0, logN0-rainrate, and slope-rainrate domain proposed in previous two studies performed well when applied to the new data if the slope and/or intercept values were changed. Another method using logN0-slope domain was not possible to classify the precipitation types well in the study area, as the best-fit line could not be obtained. The average measured D0 and Nw values obtained from polarimetric radar were compared with climatological precipitation data, measured in both the tropics and mid-latitudes. And new separation line was obtained for the rainfall at the southern part of Korea.