Wind variations around orographic rainband observed by wind profiler network in Japan

Meteorological applications of the UHF-band wind-profilers are rapidly progressed in Japan. In order to detect and predict meso-scale rainstorms, the Japan Meteorological Agency started the operation of the Wind Profiler Network and Data Acquisition System (WINDAS) in 2001. The network consists of thirty-one 1.3 GHz wind profilers installed across Japan and interval of them ranged is 130 km on average. Band-shaped meso-scale convective systems (MCSs) often appeared around Japan. Some of them lasted for a long time almost without changing its position, and caused heavy localized rainfall. In this study, we reveal wind behavior and atmospheric condition around band-shaped MCS observed in Shikoku region, Japan at 1 Aug. 2004 using three wind profiler data of WINDAS and upper air sounding data. The rainband appeared parallel to mountains' ridge (south to north direction) and maintained for about 20 hours in the atmosphere with low LCL, low LFC and large CAPE index. While the rainband observed, southerly wind was dominant and there were updraft lower layer (below 3 km height). The rainband was formed as follows; clouds were formed by upslope condensation over the mountains and blew leeward by southerly wind, and became the rainband.