热带太平洋增温分布型预估的不确定性及其校订

Global warming due to increases in greenhouse gases has been a hot topic in the global society and climatological community. Warming pattern of tropical Pacific sea surface temperature (SST) has considerable impacts on regional climate change around globe, but its projections in theory and modeling both have great uncertainties. Thus, it is one of the most important problems in research of climate change. Different from previous studies in which projections often depend on the simple average of multi-models and discard the inter-model diversity as noise, this project will use the multi-model simulations from the Coupled Model Intercomparison Project phase 5, analyze the leading modes of inter-model diversity in SST change pattern, and reveal the formation mechanisms of these models. Especially, we will emphasize the role of inter-model diversity of climatological SST pattern. We will focus on the roles of the important air–sea feedbacks in the tropical Pacific, such as the cloud–shorwave radiation–SST feedback and Bjerknes feedback. Based on the relationship between climatological SST and SST change, we can estimate the common SST change pattern induced by the common climatological SST bias among the models, and the common SST change pattern can be treated as the common change bias of the models and removed from the projections by multi-model ensemble mean. This project will deepen our understanding on the simulated future change in the models, make full use of the simulation results of multiple models, and improve our confidence on the projections of future climate change based on multi-model ensemble from statistics and physics.

温室气体引起的全球增温已是各国气候学家研究的热门问题，热带太平洋海温增温的分布型对全球区域气候变化有重要的作用。在此问题上，目前的理论和模式预估都存在很大的不确定性，是目前气候变化研究的最重要的问题之一。与前人多依赖于多模式集合平均的预估结果而将模式间偏差当噪音抛弃不同，本项目拟根据多模式的预估结果，分析模式中海洋增温分布型差异的主要模态及其成因，特别是揭示模式中气候态海温偏差在其中的作用，重点关注云辐射反馈、Bjerknes反馈等重点海气耦合过程的作用。并根据气候态海温和海温变化之间的关系，估计模式中存在的共同的气候态偏差所能造成的共同的海温变化偏差，并由此校订目前常用的简单集合平均对未来海温变化分布型的预估结果。项目的研究结果将有助于加深对模式模拟的气候变化结果的理解，更充分的利用宝贵的多模式模拟结果，从统计和物理机制两方面提高我们对未来气候变化预估的可靠性。

项目在过去4年的执行过程中基本按照项目任务书中的安排展开研究。围绕项目任务书，项目提出了全球变暖下赤道太平洋海温增暖型多模式集合平均结果的形成机制、模式间的预估不确定性及从物理机制上，提出云–辐射反馈是CMIP5多模式预估热带太平洋海温增暖型不确定性的一个主导来源，并揭示了大尺度海洋动力在CMIP5模式预估热带太平洋海温增暖型不确定性中的作用。并利用观测约束的方法指出：未来全球变暖下热带太平洋增温型将更呈现“类厄尔尼诺”的东强西弱型。研究了全球变暖下热带太平洋增暖型的不确定性对ENSO降水变化的预估不确定性的影响，对全球变暖下ENSO–西北太平洋台风关系的影响，全球变暖下热带对流对海温异常的响应变化的影响，对全球变暖下印度洋偶极子型变化的影响。项目一共发表了标注的SCI论文11篇。