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題 名 | 雙偏極化雷達資料分析梅雨鋒面雨滴粒徑分佈的物理特性=Using Dual-polarization Radar Measurements to Analyse the Microphysics Characteristics of the Drop Size Distribution of Mei-yu Frontal Rainfall |
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作 者 | 呂崇華; 陳台琦; | 書刊名 | 氣象預報與分析 |
卷 期 | 188 民95.09 |
頁 次 | 頁38-46 |
分類號 | 328.885 |
關鍵詞 | 雨滴粒徑分析; 差異反射率; DSD; Z□; Drop size distribution; Differential reflectivity; |
語 文 | 中文(Chinese) |
中文摘要 | 本研究為利用中央大學C頻雙偏極化(C-Pol)雷達進行臺灣地區梅雨鋒面通過期間降水系統特徵之觀測研究。在反演雨滴粒徑分佈及估算降雨率方面,為假設雨滴粒徑為Gamma分佈型態,並利用雨滴粒徑形狀(μ)與斜率(Λ)參數間的經驗關係式以及配合偏極化雷達觀測之回波(Z□)、差異反射率(Z□)及比差異相位差(K□)資料求得Gamma型態雨滴粒徑分佈三參數。由偏極化雷達反演雨滴粒徑分佈進而求得雲中各物理積分參數,定量上與地面雨滴譜儀觀測有良好的一致性,確認其反演參數之正確性後,將偏極化雷達反演資料應用至梅雨鋒面期間各類降水系統雨滴粒徑分佈特性,以探討其降水系統中雲物理的機制。 由本研究顯示,在二對流個案系統中,相同的高降雨率分別是由雨滴數量(相對多)及雨滴粒徑(相對大)所主導,二個案在雨滴粒徑分佈上有較不同的差異;雨滴碰撞結合及分裂過程,隨降雨率增大最終將會達到平衡,雨滴粒徑大小為一穩定值。 |
英文摘要 | The major purpose of this research is to understand the microphysics characteristics of Mei-yu forntal system over Taiwan area using NCU C-band dual-polarization (C-Pol) radar measurements. The method for retrieving drop size distribution (DSD) parameters is to assume that the drop size distribution (DSD) is represented by a gamma distribution, and an empirical relation between the distribution shape (μ) and slope (Λ) parameters. Then the three gamma parameters (N₀、μ、Λ) can be derived from the polarimetric variables (Z □、Z□ and K□) through an forward numerical calculation of scattering model. Retrieved physical characteristics of the drop size distribution (DSD) were generally well matched with disdrometer observations. The retrieval data is applied to the selected Mei-yu frontal precipitation cases to analyze the microphysics characteristics of the rainfall system. The research results indicate that two strong convective cases are dominated by relatively large drops number and relatively large drops size respectively at the same rainfall rate. Two cases have great variation in the drop size distribution (DSD). At high rain rates, the D₀ values reach a steady value what are believed to be equilibrium DSDs in which breakup and accretion are roughly in balance. |
本系統中英文摘要資訊取自各篇刊載內容。