前期春季南半球环状模对冬季热带中太平洋海温的影响及机理研究

Global climate system is a mutually interacted entirety. It has been established that the tropical climate change has a significant impact on the extratropical climate through the atmospheric bridge. And there is already growing evidence that the extratropical climate plays an important role in the tropical climate change. The leading mode of the atmospheric circulation in the Northern Hemisphere extratropics can affect the tropics through both the atmospheric bridge and oceanic tunnel. Climate variability in the Southern Hemisphere (SH) extratropical regions is dominated by the SH Annular Mode (SAM, also referred to as the Antarctic Oscillation). However, there are no systemic analyses regarding the influence of the preceding SAM on the tropical Pacific Ocean sea surface temperature (SST) and the involved physical mechanisms. This project will address this issue, and focus on the potential impacts of preceding spring SAM on the winter tropical Central Pacific Ocean SST. By using the long-term observation data sets, employing statistical analysis and dynamic diagnosis method, and combing with the theoretical analysis and numerical simulations, we expect to explore the relevant physical processes and mechanisms. On this basis, we will bring forward the concept of physical model for the connection between the preceding spring SAM and the winter tropical Central Pacific Ocean SST. The implement of relevant work would not only improve the understanding of tropical–extratropical climate interactions, also would provide a fresh perspective for enhancing predictive ability of tropical Central Pacific Ocean SST.

全球气候系统是一个有机整体，热带通过大气桥梁影响热带外气候。越来越多的证据表明，热带外对热带气候的贡献也不容小觑。北半球热带外大气环流变率通过大气和海洋桥梁影响ENSO的发生发展。南半球环状模（Southern Annular Mode，SAM，又称南极涛动）是南半球热带外环流变率的主导模态，然而目前对于前期SAM是否影响热带太平洋海温，以及可能的物理机制尚缺乏系统的研究。本项目利用长期的观测资料，通过资料统计和动力诊断，并结合理论分析和数值模拟，探讨和分析春季SAM影响冬季热带中太平洋海温变化的关键大气、海洋过程。在此基础，提出春季SAM影响冬季热带中太平洋海温的物理概念模型。相关工作的开展，有助于从南半球的角度出发，更加全面的认识热带外影响热带太平洋海温这一问题，并为提高热带中太平洋海温预报水平提供了新的视角，具有重要的科学意义和一定的应用价值。

本项目通过动力诊断和数值模拟，利用“海气耦合桥”理论，揭示了前期春季SAM与随后冬季赤道中太平洋海温异常存在显著的负相关关系。在这一过程中，印度洋海温异常和印太海气相互作用在这一关系中扮演的“海洋桥”和“大气桥”角色。这一研究，从南半球中高纬度出发，揭示了前期SAM信号通过跨洋盆的海气耦合过程调控中太平洋海温异常的物理事实，为中太平洋海温预测提供了新的预测思路，有助于更加深入全面地理解南半球热带外响热带海温这一问题，同时也会为SAM借助热带太平洋海温这一桥梁影响北半球气候方面的研究奠定基础。因此该研究不仅具有重要的科学意义，而且具有一定的应用价值。