ENSO对印度洋浅层经向翻转环流年际变异的影响机理

印度洋浅层经向翻转环流（SMOC）表现出显著的季节和年际变化特征，对印度洋上层海洋热盐再分配具有着重要影响。但是，以往研究主要聚焦年平均状态下印度洋SMOC的年际变化，而忽视了它的冬夏季节差异及其对年平均状态变化的影响。ENSO是热带印度洋环流年际变异的重要影响因子，然而其影响印度洋SMOC年际变化的物理过程及其机理却尚未明确。为此，本项目拟从印度洋SMOC的冬夏季节差异为切入点，基于资料分析、动力诊断和数值模拟等技术手段，在ENSO演变期间，系统分析冬夏季节跨赤道经圈环流和南半球副热带经圈环流的协同变化和相对独立变化，进而评估它们对印度洋SMOC年际变化的作用，最终剖析ENSO通过“大气桥”和“海洋通道”调制印度洋SMOC的主要物理过程。通过上述研究，本项目试图揭示ENSO对冬夏季节印度洋SMOC年际变异的影响机理，丰富印度洋浅层经圈环流系统细节，提高热带印度洋上层海洋环流季节预测水平。

The shallow meridional overturning circulation (SMOC) in the Indian Ocean (IO) exhibits the remarkable seasonal and interannual variability, and plays a vital role in the redistribution of temperature and salinity in the tropical upper IO. However, previous studies primarily focused on the interannual variability of the annual-mean SMOC in the IO, and they overlooked the seasonal difference in winter and summer, which might significantly affect the variation of the annual-mean IO SMOC. El Niño-Southern Oscillation (ENSO) is one of the most important factors in the interannual variation of the tropical IO (TIO) circulation, but the physical processes and the corresponding mechanisms for the influences of ENSO on the interannual variability of the IO SMOC still remain unclear. In this regard, this project will start with the research on the seasonal difference of the IO SMOC in the winter and summer. With the help of the data analysis, the dynamic diagnosis, as well as the numerical simulation, we will firstly examine the collaborative and relatively independent changes between the cross-equatorial cell (CEC) and southern subtropical cell (SSTC) during the ENSO evolution, and further explore their relatively contributions to the interannual variation of the IO SMOC, and finally investigate the physical processes for the modulations of ENSO on the IO SMOC via the “atmospheric bridge” and “oceanic pathway”. Based on the above-mentioned research, the study of this project will reveal the influence mechanism of ENSO on the interannual variability of the IO SMOC, enrich the knowledge of the Indian Ocean shallow meridional overturning circulation, and thereby improve the seasonal forecast for the upper ocean circulation in the TIO.