Investigation of the Relationship between Warm Cloud Microphysical Properties and Raindrop Size Distribution over Northern Taiwan

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題名:	Investigation of the Relationship between Warm Cloud Microphysical Properties and Raindrop Size Distribution over Northern Taiwan
作者:	圖單;Matondang, Christin Afrin
貢獻者:	遙測科技碩士學位學程
關鍵詞:	雲;雨滴;Himawari-8/9;雨滴譜儀;Clouds;raindrop;Himawari-8/9;disdrometer
日期:	2020-07-29
上傳時間:	2020-09-02 18:31:42 (UTC+8)
出版者:	國立中央大學
摘要:	暖雲及其降水，因其對輻射強迫力以及降水性質，在天氣和氣候系統中扮演重要關鍵角色。而對於雨滴粒徑分布 (Raindrop Size Distribution; RSD) 的了解，則可進一步瞭解降水的多項參數及暖雲的微物理過程。但由於時空觀測的不連續性，因此現階段對於獲知暖雲內部發生詳細過程仍然具有挑戰性。因此本研究針對臺灣地區的暖雲及伴隨的地面降水RSDs特徵進行分析，利用2017年12月至2018年1月的冬季中，所蒐集到經過時空匹配的暖雲及降雨強度，經由RSD及不同降水級距的連結性，分析其變化與多項RSD資料的相關性。所分析的暖雲資料來自日本向日葵8號地球同步衛星，而國立中央大學的地面站撞擊式雨滴譜儀（Joss-WaldvogelDisdrometer; JWD）則代表暖雲降水的相對應地面特徵。本研究發現於暖雲降水中，其雲特性具有一定特徵，亦即雲滴有效半徑（Cloud Effective Radius; CER）為20-30 µm，雲液態水路徑（Cloud Liquid Water Path; CLWP）為260-400 g m-2，雲頂氣壓（Cloud Top Pressure; CTP）為440-560 hPa 。且進一步分析雨滴譜儀資料發現，當降雨強度增加時，其雨滴為高濃度的小粒徑雨滴、較高的總量濃度（NT）、更窄與單一的截距參數（log10Nw）、更小更均勻的形狀參數（µ）和斜率參數（Λ）。分析暖雲的降水時之雲參數與雨滴參數，則得到更多的明顯特徵，因此之交互統計如：雲光學厚度（COT）與Dm和NT；CER與Dm、NT和log10Nw；CLWP與Dm、µ和Λ等的關聯性。綜整這些特徵，可得知隨著COT和CLWP的增加，Dm顯著增加；然而隨著CER的增加，Dm減小並變得均勻。相反，當CER則顯示NT和log10Nw的單峰趨勢，其峰值為20-30 µm，NT隨COT降低。µ和Λ則隨著CLWP的增加而持續減小，並且趨於恆定。這些結果表明以上雲參數對特定的雨滴參數是助於瞭解暖雲及降水過程的特性及現象。 ;Warm clouds perform a key role in the system of weather and climate. It has a considerable impact on radiative forcing and also precipitation properties. Knowledge about their raindrop size distribution (RSDs) is useful in realizing rain integral-parameters and in the understanding of precipitation microphysics. Unfortunately, as a result of the discontinuity of spatiotemporal observation, obtaining a detailed process that occurs in warm clouds is still challenging. The characteristics of rain microphysical of warm precipitating clouds on Taiwan Island are still not specifically investigated. The objective of this study is to identify the characteristics of the raindrop size distribution of warm precipitating cloud in Northern Taiwan. This research also aims to reveal how the warm cloud properties relate to the alteration in rainfall intensity and how the changes relate to their drop size distribution in Northern Taiwan during the winter season from December 2017 to January 2018. The observations and analyses are based on the space-borne satellite observation (Himawari-8/9) and in-situ surface Joss-Waldvogel Disdrometer (JWD) datasets. This study found that warm precipitating clouds observed from optically medium clouds with a preferred value of Cloud Effective Radius (CER) of 20 - 30 µm, Cloud Liquid Water Path (CLWP) of 130 - 400 g m-2, and Cloud Top Pressure (CTP) of 440 – 560 hPa. Its raindrop size features consist of higher concentration of small raindrops rather than middle and large drops with a larger mean weighted diameter (Dm), higher total number concentration (NT), narrower and more-isolated intercept parameter (log10Nw), with smaller and more homogenous of shape (µ) and slope (Λ) parameters as the rain intensity become stronger. The cloud-precipitation regimes show obvious discriminating features only on specific of the pair of the investigated cloud with the raindrops parameters, such as COT with Dm and NT; CER with Dm, NT, and log10Nw; and CLWP with Dm, µ and Λ. The result shows Dm substantially increase as CLWP increase, whereas it decreases for COT and become homogenous when CER is getting larger. In contrast, NT decreases with COT, while for CER shows a unimodal trend for NT and log10Nw with peaks of 20 - 30 µm. µ and Λ are monotonically decreased and tends to be constant as the CLWP increased. These results indicate the usefulness of these cloud parameters on specific selected raindrop parameters.
顯示於類別:	[遙測科技碩士學位學程] 博碩士論文

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