On the freezing precipitation in Korea and the basic schemes for its prediction

Abstract

This study aims to improve the forecasting skill for freezing precipitation. 102 freezing-precipitation cases were collected in South and North Korea from 2001 onward. Temperature fields on ground and atmosphere, vertical temperature profiles, geopotential fields, thicknesses fields and their spatiotemporal variations, and their combinations using the predominant-precipitation nomograms (p-type nomograms), were classified and investigated to determine whether these data could be used as predictors. It was found that 1) the combination of the thicknesses of 1000–850-hPa and 850–700-hPa was a better parameter to be used to make p-type nomograms, which is very different from the one used in the USA, and 2) 35 groups on synoptic situations out of 72 are possible conditions for freezing precipitation, and 3) 3 groups out of 35, the 1000-hPa warm-front group, the mid-level southerly (MS) category of 850-hPa, and an mid-layer warm (M-W) type in the vertical temperature profile show the greatest frequency. In spite of their increasing year-on-year trend, only a small part on freezing phenomena has been found until yet. The possibility of observation errors is the biggest problem. Additionally, the need for new equipment, the freezing rain detector (FRAD), to detect freezing precipitation automatically, is proposed. The denser observing system of FRADs and an ultra-fine gridded numerical model are suggested as a solution for the prediction of freezing precipitation.