太平洋年代際震盪對雲與輻射效應之影響：氣候模式之評估與診斷

Cloud and Radiative Balance Changes in Response to Inter-Decadal Pacific Oscillation: Global Climate Model Diagnostics and Evaluation

陳勇志(Yong-Jhih Chen)

指導教授 ： 黃彥婷

國立臺灣大學/理學院/大氣科學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201602579

摘要

本研究之目標在於探討太平洋年代際震盪對雲之影響，並估計在衛星觀測紀錄中，太平洋年代際震盪對雲量之長期趨勢的貢獻。在過去的三十年間，衛星技術的成熟使雲量觀測的可信度大幅提高。然而，在這段期間，太平洋年代際震盪的相位有相當明顯的轉變，對整個氣候系統有顯著的影響。這代表在過去觀測到的雲量趨勢，除了受到全球暖化、火山以及氣膠等外在作用力影響之外，亦可能包含了太平洋年代際震盪相位轉變的訊號。理解太平洋年代際震盪與雲之關聯，有助於我們更清楚地解釋觀測到的雲量趨勢。
我們使用了四個在全球暖化下，雲的表現最不同的氣候模式進行分析。在這些模式中，太平洋年代際震盪和雲的關聯非常相似，並和觀測的推估吻合。藉助氣候模式，我們估計在觀測期間，太平洋年代際震盪的相位轉變對於雲量趨勢的貢獻。結果顯示，和太平洋年代際震盪有關的雲量趨勢和衛星觀測之雲量的長期趨勢：一、就區域分佈而言，兩者在太平洋上的很多區域都有一致的趨勢；二、就量值而言，兩者大約在同一個數量級，顯示自然震盪對雲量趨勢的影響是不可忽略的。

關鍵字

雲回饋 ； 太平洋年代際震盪 ； 全球暖化 ； 大尺度環流 ； 衛星觀測

並列摘要

The goal of this study is to investigate the cloud responses to Inter-decadal Pacific Oscillation (IPO), and estimate how IPO contributes to the observed cloud cover trend. In the past 30 years, the reliability of observational cloud data has been largely improved by satellite measurement. During this period, in addition to the background warming of global mean surface temperature, a phase shift of IPO had also occurred, introducing changes in sea surface temperature, large-scale circulations and clouds. A better understanding of cloud changes associated with IPO may be helpful for understanding the variability of clouds in satellite records.
We investigated the IPO-related cloud changes in four global climate models (GCMs) that have the most different global mean cloud feedbacks under global warming. All of the models simulate similar IPO-related cloud changes that are consistent with observations. The contribution of IPO to observed cloud cover trend is estimated, and the magnitude is comparable to the cloud cover trend in observation. When comparing to the global warming related cloud cover trend, there are indications that the IPO and global warming may both contribute to the observed cloud cover trend in a few regions: (1) the reduction of cloud cover in the mid-latitude northwest/southwest Pacific between 30~40⁰N/S, and (2) a positive trend between 5⁰N~20⁰S and a negative trend between 25~40⁰S in the eastern Pacific. In some other regions, such as the northeast Pacific, the IPO and global warming may have the opposite contributions to the observed cloud cover trend. Our results suggest the influence of IPO may be important to the cloud cover trend observed in Pacific.

並列關鍵字

Cloud feedback ； Inter-Decadal Pacific Oscillation ； global warming ； Large-scale circulation ； Satellite observation

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