| 摘要: | 本研究工作為臺灣地區首次分析及探討在熱帶氣旋影響期間伴隨龍捲風發生的迷你超大胞（Mini Supercells）事件。臺灣時間2015年8月9日下午在高雄市茄萣區至臺南市南區發生EF0龍捲風災害事件，其損害路徑長度約7.5公里，並造成建物及車輛毀損。中央氣象局七股都卜勒氣象雷達觀測顯示龍捲風母雲具有迷你超大胞之常見觀測特徵，包括：鉤狀回波、中尺度氣旋、弱回波區、邊界弱回波區及低矮的風暴垂直尺度。綜觀及中尺度環境分析顯示，臺灣地區位在蘇迪勒颱風（Typhoon Soudelor）行進方向後側之外圍環境，潮濕的低對流層、適量的對流可用位能、低對流層高風暴相對螺旋度等條件提供迷你超大胞肇始及發展所需的對流不穩定度、水氣及強迫機制。臺灣的高聳地形強迫近地面盛行風向偏轉，導致低對流層盛行風吹向陸地之過程伴隨更顯著的風向隨高度上升順鐘向轉變之垂直風切特徵，並增加風暴相對螺旋度，而潛在的水陸過渡效應（Water-to-Land Transition Effect）亦強化近地面輻合與低對流層垂直風切，更有利迷你超大胞在海岸地區進一步增強。
This is the first study to analyze a mini supercell event that accompany a tornado at southwest of Taiwan during Typhoon Soudelor impact period. In the afternoon of August 9, 2015, an EF0 tornado occurred within Tainan and Kaohsiung area. The tornado track was about 7.5 kilometers long and numerous of buildings and vehicles were damaged. The Doppler radar observation showed that the tornado’s parent cloud has the characteristics of mini supercell including misocyclone, hook echo, weak echo region (WER), bounded weak echo region (BWER), and small storm vertical scale. The synoptic and mesoscale environmental analysis showed that Tainan was located at typhoon rear outer region of moving direction, where the moist air, moderate CAPE, high storm relative helicity at the lower troposphere that facilitate the convective instability, moisture and forcing mechanisms to trigger this mini supercell. In addition, the Taiwan terrain forces the near-surface prevailing wind to deflect and, consequently, produces pronounced clockwise veering vertical wind shear and increasing the storm relative helicity. The potential of water-to-land transition effect also intensified near-surface convergence and low tropospheric vertical wind shear, which is favorable for further strengthening of mini supercell in coastal areas. |
