雨滴粒徑分佈（DSD）是降水微物理學中的重要參數。雙偏極化雷達系統提供了高時間和高空間解析度的雙偏極化參數，可以用於反演雨滴粒徑分布。從雙偏極化參數中獲取DSD不僅可以增進天氣系統中降水微物理過程的了解和定量降水估計（QPE）的能力，而且可以用於分析天氣系統的微物理過程的演變。在這項研究中，針對3種常用的反演方法進行比較，即μ-Λ法、擬合法以及變分法。利用理想化實驗將不同DSD模型與方法結合，並以加入變分法作為對照組，了解哪種方法可以有效地減少不確定性和反演中的誤差。研究結果顯示，利用變分方法可以得到較好的反演結果而且難以透過二階的多項式擬合來正確描述μ-Λ關係。
先前一些研究已針對不同的季節、地區和降水型態進行分類，並對DSD進行分析。但是較少有研究關注於台北午後熱對流事件。在本研究中，將雨滴譜儀數據與雙偏極化雷達結合，利用上述較好的反演方法來解析不同微物理過程時DSD的演化。另外我們嘗試分析DSD的變化和不同的降水微物理過程的關聯分析，如碰撞聚合，碰撞破碎或蒸發等過程的影響。通過DSD的反演，可以在降水初期觀察到蒸發過程，導致小雨滴下降。在成熟期和消散期則會發生不同的降雨微物理過程，特別是碰撞聚合過程是成熟階段的主要微物理過程。

Drop size distribution (DSD) is an elemental parameter in Precipitating microphysics. The polarimetric radar system provides high temporal and high-spatial-resolution polarimetric data which could be used to retrieve Raindrop Size Distribution (DSD). Retrieving DSDs from polarimetric radar measurements not only can extend the capabilities of rain microphysics research and quantitative precipitation estimation (QPE) but also could be used to analyze the evolution of the precipitating weather system. In this study, three commonly used retrieved methods are compared, namely the μ-Λ method, the fitting method and the variational method. Use idealized experiments to combine different DSD models with different methods, and add variational methods to understand which method can effectively reduce uncertainty and errors in retrieval. The research results show that the variational method can get better results and it is difficult to correctly describe the μ-Λ relationship through second-order polynomial fitting.
On the other hand, the statistical relationship for DSD in previous researches had been classified by different seasons, regions, and rain types. However, seldom research focuses on the Taipei thunderstorm event. In this study, the disdrometer data combine with the polarimetric radar variables has been used to resolve explicitly the evolution of DSDs associated with different microphysics processes. Moreover, we try to categorize the feature of DSD Under the influence of collisional coalescence, breakup, or drop settling processes. In the result of retrieved DSD, the evaporation process can be observed in initial stage. Different microphysical process occurs in mature stage and dissipation stage, coalescence process is the main microphysics process in mature stage.

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