中部型El Niño海温异常的赤道非对称成因研究

中部型El Niño纬向海温异常存在显著的赤道非对称特征，表现为暖海温异常中心位于赤道中太平洋，而热带东（西）太平洋冷异常中心偏向南（北）半球。这种海温非对称结构导致中部型El Niño对东亚气候的影响与东部型El Niño的影响完全相反，其对预测我国气候异常具有重要指示意义。然而，目前中部型El Niño纬向海温赤道非对称的成因尚未明了。本项目围绕中部型El Niño过程中关键海域（热带东、中、西太平洋）海温的赤道非对称性这一核心问题，基于观测资料、同化资料和CMIP5气候模式模拟结果，通过资料分析和动力诊断等手段，系统分析热带太平洋各个关键海域海洋大气异常在中部型El Niño演变过程中的时空配置和相互作用，揭示中部型El Niño赤道非对称海温结构形成的决定性因子及其物理机制。研究结果将有助于提高中部型El Niño的预测水平，为我国气候预测提供科学参考依据。

The sea surface temperature anomalies (SSTA) show an equatorially asymmetric pattern in the Central-Pacific (CP) El Niño, presenting a warm center located in the equatorial central Pacific and the cold center over the tropical eastern (western) Pacific situated in the southern (northern) hemisphere. The equatorially asymmetric structure of SSTA may lead to the contrary influence of CP El Niño on East Asian climate from that of EP El Niño, and the CP El Niño may be considered as an important climate predictor in China. However, the formation mechanism for the equatorially asymmetric SSTA of the CP El Niño remains unclear. This project will focus on the key issue that the SSTA of the three dominant sea areas of CP El Niño exhibit significant equatorial asymmetry. Using the observed/assimilated oceanic and atmospheric datasets and the outputs of the CMIP5 climate models, the spatio-temporal distribution characteristics and the interaction of anomalous atmospheric and oceanic signals in the three dominant sea areas of tropical Pacific during the evolution of CP El Niño will be investigated through the statistical analysis and dynamical diagnosis. The factors determining the equatorially asymmetric structure of SSTA in the CP El Niño will be identified, and their corresponding physical mechanism will be revealed. Therefore, the results will contribute to the prediction of CP El Niño, and provide a new scientific basis for climate prediction in China.