지형 효과에 의한 태풍 Khanun (2012)의 강수발달

Abstract

Typhoon Khanun (2012) passed from the south to north side of the Jeju Island(width 78 km, length 35 km) from 1700 to 2200 LST on 18 July 2012, and had localized intense rainfall over 226 mm around a central mountain peak (Mt. Halla height; 1,950 m). In contrast, the relatively-weak rainfall (< 30 mm) was recorded on the southern coastal region of the island and moderate rainfall (< 100 mm) was accumulated on the northern slope. The enhancement mechanism of Khanun, which generated the localized heavy rainfall on the mountain peak was investigated using S-band Dual-Doppler radar data analysis and variational-based wind synthesis method. The precipitating region of Khanun was classified into three rain bands as BF (First rainband), BS (Second rainband), and BT (Third rainband), based on the reflectivity distribution at 2 km height. As the BF passed from the southern to the northeastern side of the island, the leading part of the BF was enhanced around the mountain peak. During the enhancement, the reflectivity (> 40 dBZ) was intensified along the southern slope of the island from surface to 2 km height. When BS moved from the southwestern to eastern side of the island, it was shortly enhanced before its arrival on the top of mountain. As the BT passed from the western to northeastern side of the island, the area of reflectivity larger than 45 dBZ was considerably enlarged and the leading part of the BT was enhanced above 2 km height over the mountain. All three precipitation region (BF, BS and BT) showed the rainfall enhancement on the slope of mountain above 1km. When the reflectivity of three precipitation region (BF, BS, and BT) was most horizontally extended 2km height, the region of convergence (negative value) was almost horizontally distributed as below -0.003 on the windward side at 1 km height. In analysis for vorticity, the region of precipitation enhancement was similar to the region of negative vorticity below 0.004 . The altitude greater than 1 km affected on the enhancement for reflectivity, rainfall, convergence, and negative vorticity.