本研究針對2017年6月2日台灣北部沿海梅雨鋒面豪大雨事件，運用Weather Research and Forecasting (WRF)模式進行多組敏感度實驗，以系統性探討地形噴流強度對鋒面移動與降雨分布的影響。鋒面於0300 LST登陸北部沿海，並滯留至1200 LST後南移，期間北部沿海累積降雨量達645 mm，最大時雨量達110 mm。CTRL模擬結果成功再現了大尺度環境與降雨特徵，北部日累積雨量達680 mm，其中491 mm在10小時內累積。敏感度實驗顯示，降低南部地形高度會削弱地形噴流，而透過Observation Nudging改變上游西南風場可間接強化地形噴流。當地形噴流較強時，鋒面輻合加強並長時間滯留於北部沿海，導致降雨集中且持續；當地形噴流較弱時，輻合減弱、鋒面加快南移，降雨則轉趨分散並減少。整體而言，在模擬結果保有相似的大尺度環境與鋒面結構下，本研究能清楚分離出地形噴流的效應，證實其在鋒面滯留與降雨分布中具有決定性影響，並深化了對地形噴流與鋒面交互作用的理解，對梅雨季豪雨的模擬與預報均具重要參考價值。

This study investigates the Mei-Yu frontal heavy rainfall event that occurred along the northern coast of Taiwan on 2 June 2017, using the Weather Research and Forecasting (WRF) model with a series of sensitivity experiments to systematically examine the influence of barrier jet intensity on frontal movement and rainfall distribution. The front made landfall along the northern coast at 0300 LST and remained quasi-stationary until after 1200 LST, during which the accumulated rainfall reached 645 mm with an hourly peak of 110 mm. The CTRL simulation successfully reproduced the large-scale environment and rainfall characteristics, with a daily total of 680 mm, including 491 mm accumulated within 10 hours. Sensitivity experiments showed that reducing the elevation of the southern terrain weakened the barrier jet, while modifying the upstream southwesterly flow through Observation Nudging indirectly enhanced the barrier jet. When the barrier jet was strong, frontal convergence intensified, and the front remained along the northern coast for an extended period, leading to concentrated and persistent heavy rainfall. In contrast, when the barrier jet weakened, frontal convergence decreased, the front advanced southward more rapidly, and rainfall became more scattered with reduced totals. Overall, under comparable large-scale environments and frontal structures, this study clearly isolates the effect of the barrier jet and demonstrates its crucial role on frontal stagnation and rainfall distribution. The results deepen our understanding of barrier jet–frontal interactions and provide important implications for the simulation and forecasting of Mei-Yu heavy rainfall events in northern Taiwan.

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