本計畫延續前兩年「人為氣膠對熱帶地區對流與環流的影響」，討論在氣膠冷卻效應下，熱帶降雨、對流、大尺度環流、及ITCZ的變化與溫室氣體的增溫影響有何差異。我們將模式模擬的個數增加到7個模式，並檢視目前在暖化情境下使用的機制，應用在冷卻情境下的可行性。發現這些機制皆可合理解釋降雨空間分布、對流厚度、強度、環流強度、ITCZ位置等的變化。第三年計畫將討論海氣交互作用在氣膠冷卻情境下所扮演的角色，由於氣膠造成的冷卻效應較偏向於北半球中高緯度地區，此驅力也許是透過海氣交互作用傳遞到低緯度地區，海溫變異(SSTA)可以分成「平均變異」及「空間分布」兩個部分，未來將使用一簡化的全球環流模式 SPEEDY與slab ocean model耦合，並計算相關的經向能量傳送，探討不同氣候趨力如何透過海溫變異項及大氣經向環流或渦流能量傳送影響熱帶地區。
This is an extent research based on the results of climate impacts from anthropogenic aerosols on tropical precipitation using seven CMIP 5 simulations. During the past years, we examined a list of known mechanisms that have been applied to explain the changes of tropical precipitation, convection, circulation, and the position of the ITCZ for the warming scenario. We found that these mechanisms are still valid for the cooling scenario and produce similar changes to the tropical weather and climate, with a reversed tendency. In the third year, we propose to investigate the role of air-sea interactions for the cooling scenario. The idea is aerosol forcing is more significant in the mid-to-high latitudes while the influences are in the tropics. The high-latitude forcing may pass the information through air-sea interactions to the tropics. The SST anomaly associated with aerosol forcing may be decomposed into a mean anomaly and the spatial pattern. We will test effects of the two components using a simplified global circulation model called SPEEDY, coupled with a slab ocean model. Then calculate the meridional energy transport by the mean meridional circulations and eddies to understand the details of the processes.
