印太暖池区域海温经向结构对我国夏季降水的影响及机理研究

The area of Indo-Pacific warm pool (IPWP) includes the warmest sea surface tempearture (SST) in the globe, which is one of the source of the global climate anomalies, and also to be an important source influencing the regional weather and climate variabilities over China. However, there are no systemic analyses regarding the temporal and spatial variabilities of the SST meridional structure over the IPWP, either of their characteristics, seasonal differences, causes, or its possible influences on the climate over China. This project will address this issue, and focus on the long term variations of meridional structure of SST over the area of IPWP, as well as its impacts on the summer rainfall over China. By using the long-term observation data sets, model outputs, employing statistical analysis and dynamic diagnosis method, and combing with the theoretical analysis, theoretical model and numerical simulations, we expect to explore the long-term variabilities in the spatial distributions, temporal evolutions, seasonal differences and causes of the meridional structure of SST over the IPWP, to discuss its influences on the atmospheric circulation anomalies, and the relevant physical processes and mechanisms. On this basis, we will explore the roles of meridional structure of SST over the IPWP in the summer rainfall variations over China. The implement of relevant work would not only improve the understanding of the variations of SST over the IPWP, also would provide some scientific references for further recognition of the climatic effects of IPWP, and helpful for providing scientific references for realizing the anomalies of summer rainfall over China, thus it would be helpful in both the scientific endeavor and practical significance.

印太暖池区域是全球海表温度最高的大暖池区域，该区域是全球气候异常的源地之一，也是影响我国天气、气候变率及异常的重要区域。然而目前对于印太暖池区域海温经向结构时空变率特征、季节差异及成因，对我国气候异常影响过程及机理尚缺乏系统研究。本项目拟利用长期的观测、模式资料，通过资料统计和动力诊断，结合理论分析、理论模型及数值模拟，研究印太暖池区域海温经向结构长期变率的时间、空间分布特征，比较、对比其变化的季节差异，揭示其季节差异的成因，探讨其变率对于大气环流异常的影响,明确其中的物理过程和机制。在此基础上，研究印太暖池区域海温经向结构影响我国夏季降水的过程和机理。相关工作的开展，不仅有利于我们深入理解印太暖池区域海温变异特征，并将为我们深入认识我国夏季降水异常成因提供科学参考，具有重要的科学及现实意义。

项目通过资料统计、动力诊断、理论分析并结合数值模拟，从理论上首次定量化给出了Hadley环流响应热带海温不同经向结构的差异，并结合观测数据、理论模型，数值模式对上述不同响应差异进行了综合分析和论证。分析了气候背景对Hadley环流响应热带海温不同经向结构的调制作用，解释了过渡季节Hadley环流差异形成原因。结果发现，对于同等强度的热源强迫，由于其经向结构分布不同，Hadley环流对于关于赤道非对称热源强迫产生的异常振幅量级为关于赤道对称部分热源强迫的5倍，这种响应差异具有显著的季节依赖性，冬夏季节的响应差异明显小于春秋季节，表明在过渡季节，Hadley环流对于海温经向结构的分布更为敏感。同时，研究发现两类ENSO现象的暖事件对应着不同经向结构的海温异常分布，东部型暖事件在发展期对中国降水的显著影响主要存在于发展期的秋季，而中部型暖事件在发展期对中国降水的显著影响主要表现在发展期的夏季。这些结果为理解热带海洋的气候效应，Hadley环流的长期变率归因有一定的科学意义。.围绕项目研究目标，项目执行期间完成受项目资助的SCI论文14篇。另外，目前还有两篇SCI文章在审稿中。依托项目参加国际会议2次，国际短期交流2次。