預測全球暖化造成的熱帶乾旱

CCUR > College of Natural Science and Engineering > College of Science > Department of Atmospheric Sciences & Graduate Institute of Earth Science / Atmospheric Science > thesis > Item 987654321/27418

Please use this identifier to cite or link to this item: https://irlib.pccu.edu.tw/handle/987654321/27418

Title:	預測全球暖化造成的熱帶乾旱 Prediction tropical drought under global warming
Authors:	陳昭安
Contributors:	大氣科學研究所
Keywords:	全球暖化落井下石機制對流區邊緣 global warming the upped-ante mechanism
Date:	2006
Issue Date:	2014-06-05 13:36:32 (UTC+8)
Abstract:	從模式資料顯示，當溫室氣體濃度增加時，降雨變化並非如同氣溫或地表溫度存在普遍增溫的現象，而係顯現正負錯綜的不一致分布，因此，本研究目的在於希望從了解影響區域降雨變化的物理機制，進而預測全球暖化對區域降雨，尤其是降雨減少地區之影響。對於熱帶雨量減少的部份，落井下石機制(the upped-ante mechanism)說明了降雨減少地區主要發生在有乾平流逸入的對流區邊緣(margins)。在模式資料的分析中，落井下石機制與降雨減少地區之空間分布相當一致，顯示落井下石是造成熱帶地區降雨減少的主要動力機制，意即可利用此機制作為評估區域降雨是否減少之工具。由於落井下石機制與全球暖化下發生熱帶降雨減少的區域，具有良好的關連性，因此在本研究中，透過落井下石機制與正常氣候之關聯—有乾平流進入之對流區邊緣，制定一組條件，量化定義對流區邊緣，分析模式與觀測資料，檢驗此定義之區塊與落井下石機制區域的分布是否一致。在分析模式的結果顯示，定義為對流區邊緣之地帶，確實與受落井下石機制影響造成雨量減少之區域相當吻合，其中以夏季的加勒比海與南美洲北部，以及冬季的南美洲東部的分析結果最為理想，然而吻合程度的高低則隨區域不同而異，代表著對流區邊緣的制定可能存在區域性的差別，而無法以單一的限定條件作評斷。觀測資料的分析中，在部分已具有明顯雨量減少趨勢之地區，與對流區邊緣存在一致的空間分布，其中又以夏季的加勒比海與非洲地區的分析結果最為理想，這也意謂著落井下石機制是造成這些區域降雨減少的重要因素。 In almost all climate model simulations, as the greenhouse gases increase, warmer troposphere and surface are found globally. In contrast, changes in precipitation exhibit positive and negative anomalies. Thus, the impacts of global warming on precipitation are difficult to detect when averaging the precipitation anomalies globally. Two mechanisms have been proposed for inducing such precipitation anomalies in the tropics: the rich-get-richer mechanism for positive anomalies and the upped-ante mechanism for negative anomalies. To detect the impacts of global warming on precipitation, the areas dominated by the upped-ante mechanism are examined first. In the upped-ante mechanism, dry inflow from non-convective regions tends to suppress convection and induce negative precipitation anomalies over margins of convective regions. To determine the margins of convective regions with dry inflow, a set of quantitative criteria was made based on current climate. These criteria are used to identify the regions where precipitation will be reduced in the future due to global warming. Comparing those margins and the areas with negative precipitation anomalies found in climate modal simulations, the consistency between these two regions may differ region by region, but negative precipitation anomalies are often found over margins of convective regions. These criteria for the margins are further used to examine the observation. Even though the results are still not statistically significant for most regions due to relatively short history of observations, the tendency of reduced precipitation over the margins is clear. More analyses among different climate model simulations in IPCC AR4 will be examined in the future.
Appears in Collections:	[Department of Atmospheric Sciences & Graduate Institute of Earth Science / Atmospheric Science ] thesis

Files in This Item:

There are no files associated with this item.

View Licence

Loading...