소백산맥 풍하측 강풍의 종관 유형 분류와 중규모 메커니즘 분석

Abstract

While many previous studies have been conducted on the downslope windstorms (DWs) in the lee of Taebaek Mountains in Korea, no such research has been focused on the lee of Sobaek Mountains at which the DWs often caused wild fires and wind gusts with flight delays. We selected 1,950 cases of DWs in the lee of Sobaek Mountains and classified the mean sea-level pressure patterns into eight clusters using Self-Organizing Map. We found that there are two distinct types: low-passing (Type 1 in Spring, clusters 1 and 5) and west-high and east-low (Type 2 in Winter, clusters 4 and 8) patterns. Others are found to be the transitional patterns between these two types. Using reanalysis and upstream sounding data, we identified that the Type 1 had a more pronounced Foehn effect on the lee of Sobaek Mountains. And, the hydraulic jump was found to be the main mechanism for the DWs in Type 2 with an inversion layer on the windward side especially in clusters 6, 7 and 8 in the case of stratified flow. The partial reflection mechanism was dominant in most types with some differences depending on horizontal wavelength of the mountain wave. Critical-level reflection mechanism was also important in Type 1. DWs in the lee of Taebaek Mountains happened more under the south-high and north-low pattern, which was not the case in the lee of Sobaek Mountains. Type 2 with one case showed a similar mechanism to the Bora wind with hydraulic jump and no critical-level reflection.