全球增暖1.5/2度情景下中国降水变化的动力和热力机理及不确定性

The response of global and regional climate to 1.5 and 2 degrees of warming is a great challenge in the field of climate change research. In the complex East Asian monsoon climate area, there is great uncertainty in the precipitation projection under the background of weak warming such as 1.5 degree. Understanding its physical mechanism is very important for improving the credibility of the projection results. The project seeks to find out the dynamic and thermodynamic mechanism as well as the cause of uncertainty in the projected changes of precipitation in China at 1.5 and 2 degrees of warming. For this purpose, We will use the simulation results of international research program for the 1.5 targets, combined with that of CMIP5 RCP2.6 and 4.5 scenarios, changes in precipitation and monsoon circulation system under the 1.5 and 2 degrees of warming scenarios; on this basis, contribution of dynamic term (induced by changes of wind) and thermodynamicterm (induced by changes of specific humidity) to precipitation changes will be analyzed quantitatively; The effects of anthropogenic external forcing and the internal variability of climate systems on precipitation projection will be evaluated, and the main sources of uncertainty of future precipitation in China will also be analyzed. The results of this project will deepen the scientific understanding of the physical mechanism of regional scale precipitation change, improve the credibility of future precipitation projection in our country, and provide theoretical basis for a better adaptation to climate change.

1.5/2度温升下全球和区域气候的响应是当前气候变化研究领域面临的巨大挑战。在复杂的东亚季风气候区，弱增温背景下的降水预估存在较大不确定性，理解其物理机制对于提高模式预估结果的可信度至关重要。项目试图弄清1.5/2度下中国降水变化的动力、热力机理及不确定性的产生原因。为此，将利用当前国际上针对1.5度阈值研究计划的最新模拟结果，结合RCP2.6和4.5情景下的CMIP5模式资料，系统研究增暖1.5和2度情景下中国降水和东亚季风环流的变化特征；在此基础上，定量研究动力项和热力项对降水未来变化的相对贡献；评估气候系统内部变率和外强迫对降水预估的影响，分析我国降水预估不确定的主要来源。本项目的研究成果将加深对区域尺度降水变化物理机制的科学理解，提高我国未来降水预估的可信度，并为更好地适应气候变化提供理论依据。

本项目研究了中国区域平均和极端降水对于全球增暖1.5和2度的响应特征及可能成因。研究过程中取得的进展主要包括：.1)评估了气候模式对东部季风区平均和极端降水的模拟能力，优选了偏差订正方法.2)揭示了全球增暖1.5/2℃下中国区域极端降水的风险变化及其影响因子.3)揭示了未来变暖背景下中国区域平均和极端降水的萌现时间（ToE），分析了模式不确定性和内部变率对ToE的影响.4)揭示了变暖背景下中国区域复合干旱热浪事件的变化特征.