Changes of Tropical Tropopause in Response to Global Warming

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Title:	Changes of Tropical Tropopause in Response to Global Warming
Authors:	蘇瑋;Su, Wei
Contributors:	大氣科學學系
Keywords:	對流層;全球暖化
Date:	2020-07-29
Issue Date:	2020-09-02 14:54:41 (UTC+8)
Publisher:	國立中央大學
Abstract:	此篇論文使用ERA-Interim再分析資料，以及CMIP5模式情境模擬資料，來研究熱帶對流層頂在全球暖化下的變化。其中包含三種對流層頂定義方式，分別為使用溫度遞減率的熱力法、以位渦定義的動力法，以及與臭氧濃度相關的化學法。由長期氣候態中可發現，緯向平均後的對流層頂在使用熱力法下，與前人的研究結果一致，動力對流層頂在中緯度地區表現不錯，但是無法適用於赤道低緯地區，而化學法在與前兩種方法相比下稍嫌不足。因此，在後續的研究當中，會使用熱力法來作為定義對流層頂的方式，且集中在熱帶地區。季節變異方面，再分析資料的結果顯示，北半球冬季對流層頂高度在40年平均下比夏季高約500m，氣壓則是低約10hPa。本篇研究中使用CMIP5 rcp8.5暖化情境模式資料來模擬對流層頂在全球暖化下的變化，與前人研究結果相符，對流層頂高度增加伴隨著對流層頂氣壓降低，氣壓下降率為約1.43hPa/decade，高度上升率則為128.57m/decade。後根據全球SST(海表面溫度)的EOF(經驗正交函數)分析，以及對其進行對流層頂氣壓的迴歸分析，結果顯示聖嬰-南方振盪現象(ENSO)與全球暖化(Global Warming)兩者皆會影響對流層頂，使其產生變化。 ;Changes of the tropical tropopause under global warming is studied using the ERA-Interim reanalysis datasets and the CMIP5 model simulation outputs. Three methods of the tropopause definition are used, including the thermal, dynamical, and chemical ones. The long-term climatology shows that the tropopause is well defined in the tropics using the thermal method, the dynamical method is proper in the mid-latitudes but failed in the deep tropics, and the chemical method has some deficiencies compared to the other two. This study thus focuses on the tropical regions and chooses the thermal method to do the following researches. 　　For the global-mean seasonal variations, Northern winter tropopause height (pressure) is about 500m (10hPa) averaged higher (lower) than the summer one in the 40 years. Coincide with previous studies, the tropopause pressure tends to decrease when the tropopause height increases in the CMIP5 rcp8.5 scenarios, with a　decreasing rate of about 1.43hPa/decade, and an increasing rate of nearly 128.57m/decade. According to the empirical orthogonal function (EOF) analysis of the SST fields, and the regression maps of the tropopause pressure onto the SST modes, El Niño-Southern Oscillation (ENSO) and Global Warming both may have impacts on the variability of the tropopause.
Appears in Collections:	[Department of Atmospheric Sciences and Graduate Institute of Atmospheric Physics ] Department of Earth Sciences

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