線狀中尺度對流系統三維風場反演之驗證與分析-2022 TAHOPE IOP3 個案;The verification and analysis of 3-D wind retrievals for a linear Mesoscale Convective System - 2022 TAHOPE IOP3

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题名:	線狀中尺度對流系統三維風場反演之驗證與分析-2022 TAHOPE IOP3 個案;The verification and analysis of 3-D wind retrievals for a linear Mesoscale Convective System - 2022 TAHOPE IOP3
作者:	蘇琦竣;Su, Chi-Chun
贡献者:	大氣科學學系
关键词:	中尺度對流系統;冷池;RHI
日期:	2025-08-19
上传时间:	2025-10-17 11:05:31 (UTC+8)
出版者:	國立中央大學
摘要:	台灣區域豪大雨觀測暨預報實驗(TAHOPE) IOP3期間，伴隨平行層狀降水(PS)特徵的梅雨鋒前中尺度對流系統(Mesoscale Convective System)於2022年6月6日通過台灣北部區域，為了探討此對流系統的動力型態變化特徵與周圍環境之交互作用關聯，本研究採用多都卜勒三維風場反演方法(Wind Synthesis System using Doppler Measurements, WISSDOM)，結合多種觀測資料進行動力特徵分析。為了確立變分反演準確性，透過敏感度測試並結合移動式研究雷達(TEAM-R)之RHI(Range Height Indicator)掃描觀測，定量驗證分析對流區域內垂直風場。分析變分反演方法中的平滑項與徑向風三維風場關係式之約束條件，其權重參數與雷達數量對於反演之水平風場與垂直速度的敏感度及準確性。結果顯示過高的徑向風權重參數容易降低反演風場的準確性，以及低層若有更寬廣及愈多的雷達觀測覆蓋，可更準確反演對流區域內的對流特性及垂直風場結構。此驗證結果將應用於後續此個案之反演分析。根據反演風場與回波型態的演變，顯示MCS初期多個孤立胞位於主對流系統南側，當主對流接近北部近岸時，對流胞逐漸向北併入於主對流中並形成近岸增強的對流結構，此過程可歸因於鋒前低層地形噴流與對流降水形成之輻散氣流輻合，隨著時間演變，地形噴流的影響範圍與強度開始減弱。之後主系統轉變為西南至東北走向並在近岸形成後造型對流。隨著對流開始減弱，第二後造型對流開始在海上發展並經歷兩次對流增強過程，第一次增強源於對流合併過程，當系統向東移入至苗栗時，其降水引發的冷池之北風與環境西南風輻合形成第二次對流增強，此過程造成苗栗地區產生大於每小時90毫米的降雨強度。當系統向東北方移動並受到雪山山脈影響後，對流高度下降與回波減弱特徵顯示系統將逐漸消散。總結而言，經驗證之WISSDOM的合成風場可準確掌握對流系統的強度與風場演變，並有助於調查強降雨事件伴隨的動力特徵。期望未來可與模式預報的風場進行比較評估。 ;A prefrontal linear Mesoscale Convective System (MCS) with Parallel Stratiform (PS) approached northwestern Taiwan on 06 June during TAHOPE2022. To investigate the kinematic characteristics of this convective system, the three-dimensional wind field was retrieved using the WInd Synthesis System using Doppler Measurement (WISSDOM). Range Height Indicator (RHI) observations were incorporated into the validation process to assess the performance and sensitivity of the retrieved wind field with respect to the weighting coefficients and the number of radars. The results reveal that excessively high radial wind weighting coefficient reduces the accuracy of retrieved wind field, while greater radar observation coverage at low levels leads to a more accurate depiction of convective characteristics and vertical velocity structures. From the synthetic wind field and the evolution of radar echoes, multiple cells appeared in the southern part of the main convective system during the early stage. These convective cells began to merge northward into the main system, forming a near-coastal intensification structure as the system approached northern Taiwan. This process can be attributed to the convergence between the prefrontal barrier inflow jet and the divergent flow generated by precipitation. Over time, the barrier jet gradually weakened in both intensity and spatial extent. Thereafter, the main system shifted to a southwestward orientation with a back-building convective structure near the coast, followed by a brief weakening of convection. Eventually, a second back-building system reorganized over the ocean and underwent two intensification processes: the first resulted from a merging process, while the second was associated with the convergence between the southwesterly environmental flow and the northerly wind produced by cold pool as the system moved inland, producing heavy rainfall exceeding 90 mm per hour over Miaoli. The decreasing convective level and reflectivity intensity suggest that the system will dissipate as it moves northeastward and becomes affected by the Snow Mountain Range. In conclusion, the verified synthesized wind field derived from WISSDOM can accurately capture the intensity evolution of the convective system and wind field, and is helpful for investigating the kinematic characteristics of the heavy rainfall event. It is hoped that the result can be compared with the model forecast.
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