南半球热带外海温对南半球极锋急流的影响及机理

Studies in recent years have indicated that variability of extratropical sea surface temperature (SST) plays a significant role in regulating climate anomalies. Under the background of gradually increased understanding about influences of Northern Hemisphere extratropical SST on atmospheric circulation, it is particularly urgent to study the corresponding processes in the Southern Hemisphere (SH). Specially, on the aspect of influences of SH extratropical SST on the SH polar jet (SHPJ), there are no systemic and deepgoing analyses until now. The SHPJ is an important member in global atmospheric circulation system, and studying its variability is helpful for comprehending characteristics of climate in the SH middle and high latitudes and the associated circulation in the tropics. By using the reanalysis datasets and multi-model outputs from Coupled Model Intercomparison Project, employing statistical analysis and dynamic diagnosis methods, and combing with numerical simulations, we expect to investigate the key SST anomalies patterns in SH extratropics affecting the SHPJ, and understand the corresponding mechanisms. On this basis, we will explore the contribution of SH extratropical SST to long-term changes of the SHPJ, and address whether differences between models in depicting this process can be used to explain differences between models in simulating the long-term trend of the SHPJ. The implement of relevant work will provide new information for recognizing influencing factors of the SHPJ and understanding air-sea coupling mechanisms in the extratropics, and provide scientific references for improving model performance in simulating the long-term changes of the SHPJ.

近年来的研究表明，热带外海温变率在调控气候异常方面发挥着显著作用。在北半球热带外海温对大气环流的影响得到逐步认识的背景下，对南半球的相关研究变得尤为迫切。特别是在南半球热带外海温对南半球极锋急流的影响及机理方面，目前尚缺乏系统、深入的认识。南半球极锋急流是全球大气环流系统的重要成员，对它的研究有助于理解南半球中高纬度气候和与之联系的热带环流的变化规律。本项目利用再分析资料和耦合模式比较计划的多模式输出，通过资料统计和动力诊断并结合数值模拟，研究影响南半球极锋急流的关键热带外海温异常型，认识其中的动力机制。在此基础上，探讨南半球热带外海温对极锋急流长期变化的贡献，分析多模式间对这一过程的不同刻画是否可以解释模式间对极锋急流长期趋势模拟的差异。相关工作的开展，将为认识南半球极锋急流的影响因子和理解热带外海气耦合机制提供新的信息，并为气候模式提升对南半球极锋急流长期变化的模拟提供科学参考。

热带外海温异常对大气环流的影响是近几十年来在国内外得到迅速发展的研究领域之一。围绕南半球热带外海温对南半球极锋急流的影响，有许多有价值的科学问题值得深入探讨。本项目涉及的关键科学问题，南半球热带外海温对极锋急流前两个主要模态年际变率和长期趋势的影响，是对现有研究的进一步发展。本项目的研究结果表明，南半球热带外海温异常对极锋急流的第一 (SAM) 和第二 (LLM) 模态均有影响，不同模式对极锋急流长期变化模拟的差异，与模式刻画的南半球热带外海温对极锋急流的影响有关，并对其中物理机理的进行了深入探索，为认识南半球极锋急流的影响因子和理解南半球热带外海气系统耦合过程提供了新的信息，并为气候模式提升对南半球极锋急流长期变化的模拟提供科学参考。