| 摘要: | 降水依據時空分布特性的不同，可分為層狀降水與對流降水兩種型態。層狀降水所涵蓋的水平範圍較大、持續時間長、垂直對流運動較不活躍；而對流降水水平範圍較小、持續時間短、垂直對流運動旺盛。從雷達回波的水平剖面圖來看，對流降水區域是呈小區塊狀不規則地散佈在層狀降水區域內，回波強度明顯比周圍高；而層狀降水區域則是環繞在對流降水區域外圍，範圍明顯比對流降水區域還大許多。 本研究依照Steiner et al. (1995)、Yang and Houze (1995) 以及Tremblay (2005) 三種降水型態分類方法分析台灣地區的降水資料，測試各方法應用於台灣地區的可行性。研究中選取2004年春雨、梅雨、颱風、西南氣流、夏季雷雨及東北季風降雨共六種代表不同天氣型態的降水個案，並且以不同的降雨量內插方法測試其空間敏感度，發現Steiner et al. (1995)、Yang and Houze (1995) 兩種降水分類方法的結果相當一致。在各降水個案中，春雨的對流降水最高體積比例約8%~27%，梅雨約48%~70%，颱風約74%~85%，西南氣流約82%~92%，夏季雷雨約72%~94%，東北季風降雨約24%~75%。而根據Yang et al. (2007) 納莉颱風數值模擬研究中地形敏感度實驗降水資料的分析，結果更顯示了台灣地區複雜的地形對於對流降水與層狀降水兩種降水型態的分佈有很大的影響。 We can partition precipitation into stratiform and convective components by their spatial and temporal characteristics. General speaking, the significant features of stratiform precipitation include larger rainfall area, longer period, and vigorous vertical convection. On the contrary, the characteristics of convective precipitation are smaller rainfall area, shorter period, and weakly vertical convection. The convective regions of precipitation locally scatter inside the stratiform regions, and the radar echo of convective precipitation is evidently stronger than the background echo. The stratiform regions of precipitation distribute around the convective regions, and the area of stratiform region is generally bigger than convective regions. The purpose of this study is to analyze the precipitation data in Taiwan by the precipitation separation scheme of Steiner et al. (1995), Yang and Houze (1995), and Tremblay (2005). Six precipitation events in 2004—spring rainfall, Mei-Yu front, Typhoon Mindulle, the southwesterly flow triggered by Typhoon Mindulle, summer thunderstorm, and autumn cold front—were selected. We found that the convective precipitation percentage of the six rainfall events determined by the method of Steiner et al.(1995) is similar to that by the method of Yang and Houze(1995). The highest convective precipitation volume percentage is about 8%~27% in spring rainfall, 48%~70% in Mei-Yu front, 74%~85% in Typhoon Mindulle, 82%~92% in the southwesterly flow triggered by Typhoon Mindulle, 72%~94% in summer thunderstorm, and 24%~75% in autumn cold front. Analyzing the simulated surface rainfall of terrain-sensitivity experiments of Typhoon Nari(2001) by Yang et al.(2007), we conclude that the distribution of convective and stratiform precipitation is strongly affected by Taiwan terrain. |
