本計畫延續第一年「人為氣膠對熱帶地區對流與環流的影響」,在氣膠冷卻效應下,熱 帶降雨的空間變化與溫室氣體的增溫影響相當類似,但是變化的符號相反,這個結果可 以用「富者越富」及「首注提高」兩個機制合理的解釋。關於對流與環流的影響,我們 發現有些模式的深對流區對流高度降低、對流強度增強,變化的趨勢與暖化相同,但是 後續研究想採用的Community Earth System Model version 1 (CESM1) 及其類似的模式 NorESM 則是對流強度及高度都增加,與預期的變化不同,因此需要進一步的分析以釐 清CESM1 對氣候驅力的反應所具有的特徵。本計畫使用 CESM1 搭配一中等複雜度的 氣候模式(the University of California, Los Angeles Quasi-Equilibrium Circulation Mode, UCLA QTCM)進行類似的冷化實驗,先測試空間解析度是否為造成模擬結果差異的因 素,並探討熱帶對流高度及環流型態如何透過海氣交互作用在全球溫度改變時產生變化。
This is an extent research based on the results of climate impacts from anthropogenic aerosols on tropical precipitation using four CMIP 5 simulations. In the previous project, we found the tendency of tropical precipitation change due to aerosol cooling effect is nearly opposite to that of greenhouse gases in terms of its spatial pattern. This response can be explained by the “rich-get-richer” and “upped ante” mechanisms reasonably. In terms of the convection depth and circulation strength, some of the models show decreasing in convection depth and increasing in convection intensity which are consistent with the responses of the warming situation. However, the responses of CESM1 and NorESM (which is modified from CESM1) show both increasing in convection depth and intensity in cooling simulations. It is necessary to investigate the details of CESM1 response to anthropogenic aerosols. We propose to perform similar cooling simulations using the Community Earth System Model version 1 (CESM1) and use an intermediated complex climate model (the University of California, Los Angeles Quasi-Equilibrium Circulation Mode, UCLA QTCM) to investigate the possible processes that may modify tropical convection and circulations in the cooling simulations. We will analyze moisture budget and moist static energy budget and discuss influences from sea surface temperature spatial patterns and values.