中世纪暖期和现代暖期亚洲季风系统对不同气候强迫因子的响应差异及机理研究

Persistent episodes of extreme weather in Asia have been shown to be associated with the changes in Asian monsoon under the present global warming. However, various climatic and anthropogenic factors can affect the Asian monsoon precipitation during the Present Warm Period (PWP). It is very difficult to attribute Asian monsoon precipitation responses to different climate forcings, especially natural and anthropogenic climate change signal, during the PWP. In order to distinguish the contributions of natural and anthropogenic forcings on Asian monsoon precipitation in this century, it is crucial to understand how the Asian monsoon precipitation has evolved in a warming background, which is likely similar to 20th-century warming, “purely” driven by natural variability, over the past 1000-2000 years. Therefore, in this proposal, many sets of simulations would be carried out by employing Community Earth System Model (CESM) with different climate initial fields, and driven by the reconstructed total solar irradiation (TSI), greenhouse gases (GHGs), volcanic aerosol (VOL), land use and land cover (LULC), natural forcing, anthropogenic forcing and all above forcings, respectively, over the warmest centuries in the Medieval Warm Period (MWP, ~A.D. 850-1300) and PWP. The modeling results will be evaluated by model-proxy data comparison and model-observation data comparison. Base on modeling results, the analysis will be made to understand the major characteristics and mechanisms of the Asian monsoon precipitation during the MWP and PWP. The effect of the natural and anthropogenic factors on Asian monsoon precipitation over the MWP and PWP will be evaluated. Finally, quantifying the influence of climate forcings and feedbacks on Asian monsoon precipitation over the MWP and PWP.

全球快速变暖导致亚洲各国极端气候事件频繁发生，其中亚洲季风降水变化的影响不容小觑。如何评估不同气候强迫因子，特别是自然变率与人类活动对现代百年暖期亚洲季风降水的影响，是当今科学界关注的热点。要想解决此问题，需在历史时期中寻找与现代百年暖期温暖程度相类似的“纯自然”暖背景进行对比研究。为此，本项目拟以“中世纪暖期”和“现代暖期”为研究背景，以整个亚洲季风系统为研究对象，在前期研究基础上，利用地球系统模式CESM对两个“百年”暖期分别进行多组不同初始场驱动的气候模拟试验，包括太阳辐射、火山活动、温室气体、土地利用、自然因子和人类活动敏感性试验以及真实强迫试验，并利用历史时期气候代用资料和多模式资料验证本试验结果，分析亚洲季风气候在“中世纪暖期”和“现代暖期”的特征差异及驱动机制，定量化评估不同气候强迫因子对百年暖期亚洲季风降水的影响，力图为百年尺度亚洲季风气候研究做出贡献。