海温模态跨海盆联动过程对ENSO形成演变的影响

ENSO is one major factor for climate prediction. However, ENSO predictions have encountered unexpected challenges in recent years, leading some uncertainties for the prediction of East Asian Monsoon. The transition of ENSO evolution might be influenced by the climatic signals outside of the tropical Pacific. Those climatic signals include the several different modes of sea surface temperature anomalies (SSTA) in the subtropical North/South Pacific, the tropical Indian, and the tropical Atlantic. These SSTA modes can affect each other and there are apparent inter-basin interactions among them. In this project, we plan to investigate the dynamics of the inter-basin interactions of those SSTA modes and their effects on the ENSO formation, mainly based on numerical sensitive experiments and some analyses based observed datasets. Emphasis will be paid on several key questions: 1. To find the potential configurations of different SSTA modes that might influence the ENSO formation effectively. 2. To describe the relative contribution of SST modes in different scenarios. 3. To investigate the mechanism of inter-basin interaction of those SSTA modes and their influence on ENSO formation. 4. To obtain the key configurations of SSTA modes that can effectively determine the turning point of ENSO formation. If the configurations of those SSTA modes can be defined, it will be a useful new skill for improving ENSO prediction.

ENSO是全球许多区域气候预测的主要因子，然而近年来ENSO预测屡遭挫折，并对东亚季风乃至全球气候预测带来不确定性影响。尽管ENSO事件的初始发展状态相似，但ENSO事件的形成演变却会表现出转折性变化，其原因不仅源于热带太平洋海气相互作用，同时也受到副热带北/南太平洋、热带大西洋、热带印度洋等海温模态协同变化和跨海盆尺度相互作用的影响。为此，本项目将主要利用气候模式进行敏感试验并结合资料诊断分析，重点研究（1）影响ENSO事件形成的转折性演变的各海温模态不同时空配置；（2）不同海温模态共存时各模态对ENSO事件形成演变的相对贡献；（3）在ENSO事件不同发展位相对ENSO转折性演变起到决定性影响的关键海温协同模态。通过上述研究，本项目将揭示海温多模态的跨海盆联动过程对ENSO形成演变的影响和物理机理，并为ENSO气候预测提供相关的科学依据，研究结果对提高我国短期气候预测也具有重要参考价值。

近年来ENSO预测屡遭挫折，夏秋季预测的ENSO事件多次发展滞缓甚至意外夭折，ENSO演变机理及其预测理论的研究具有重要意义。项目研究了南北太平洋副热带海温异常模态对ENSO演变的调控作用，基于资料诊断分析和数值试验，对历次ENSO演变过程的不规则特征进行分析，指出南北太平洋副热带海温的不用配置对ENSO的演变有着重要影响，其中副热带太平洋海温异常导致的信风改变可以引起赤道西风异常，进而影响ENSO演变。.研究了在动力预测系统中初始偏差可导致厄尔尼诺预测失败的过程和机制，定义了ENSO时空演变模态并构建了ENSO监测模型，比较分析了赤道太平洋西风爆发在PDO正位相和PDO负位相期间的特征差异，定义了一个更适于描述ENSO和西风爆发的新指数（赤道振荡指数），评估了CMIP5和CMIP6模式对印度洋显著增暖现象的模拟性能，发现自1990年代中期西南印度洋持续稳定增暖现象并给出物理成因解释。.项目在国际学术刊物及国内核心刊物上发表相关研究论文8篇，其中SCI（E）5篇。