Hadley环流作为低纬度地区最重要的经向环流，其垂直方向和水平方向的运动将对流层的上下层以及热带和副热带紧密联系在一起。因此，Hadley环流的变化对全球以及区域气候有重要的影响。前人研究表明，热带海表面温度（SST）经向结构对Hadley环流的变化有着重要的影响，并且两者之间的关系受到气候变率的调制。本文利用多种大气、海洋资料和数据集研究了大西洋多年代际振荡（Atlantic multidecadal oscillation，AMO）对Hadley环流与热带SST不同经向结构之间关系的影响，并解释了造成其在冷、暖位相对两者关系影响差异的可能物理原因。

    结果显示，AMO冷、暖位相对Hadley环流与热带SST经向结构之间关系的影响存在着显著区别。当AMO处于暖位相时，Hadley环流对热带SST不同经向结构的响应明显小于气候平均，而冷位相的结果则与气候平均的结果相当。AMO冷、暖位相对热带SST经向结构与大气环流之间关系影响的显著差异主要与其冷、暖位相时对印太暖池区域SST不同的影响有关。在AMO暖位相时，印太暖池区域SST南、北半球间变冷振幅不同，造成SST经向结构变化，使得气候平均的SST南北半球温差增大，对应着热带SST关于赤道非对称分量的增强，从而导致AMO暖位相时Hadley环流对热带不同经向结构的SST响应减弱。而在AMO冷位相时，印太暖池区域南、北半球SST变冷振幅相当，气候平均的SST南北半球温差基本不变，导致AMO冷位相时Hadley环流对热带不同经向结构的SST响应与气候平均的结果相当。以上结果，可以通过其它的大气再分析资料得到进一步印证。

    最后，我们评估了23个Coupled Model Intercomparison Project 6（CMIP6）耦合模式对AMO影响Hadley环流与热带SST不同经向结构关系的模拟能力。结果显示CMIP6模式能够很好的模拟气候平均的AMO，Hadley环流和热带SST经向结构空间分布特征以及Hadley环流与热带SST经向结构主导模态的空间分布特征。在此基础上，我们进一步评估模式模拟AMO冷、暖位相时Hadley环流与热带SST经向结构之间关系的能力。发现模式间对两者关系的模拟能力存在显著的差异。能够较好的模拟出AMO冷、暖位相对热带SST经向结构与大气环流之间两者关系影响显著差异的模式，主要是因为能够较好的模拟出AMO冷、暖位相对热带印太暖池区域SST的非对称影响。以上结果进一步印证了AMO的年代际变化对于热带海气过程的重要影响，相关结果表明AMO对于热带海气过程具有显著的调制作用，有助于深入认识热带海气过程异常的物理机理。

    As the most important meridional circulation in low latitudes, the vertical and horizontal movements of Hadley circulation (HC) closely bridge the lower and upper troposphere, as well as the tropics and subtropics. Therefore, changes in the HC can have important impacts on global and regional climate effects. Previous studies have shown that the HC depends on the meridional distribution of the underlying tropical sea surface temperature (SST). The relationship between HC and SST meridional structure is modulated by climate variability. In this paper, the effects of the Atlantic Multidecadal Oscillation (AMO) on the relationship between the varying response of the HC to different SST meridional structures are investigated by using a variety of atmospheric and oceanic data and datasets. And the potential mechanisms for the varying response of the HC to different SST meridional structures under warm and cold phases of AMO are also explained.

    It was found that the response contrast of the HC to different SST meridional structures differs between warm and cold phases of AMO. The response contrast of HC to SST during the cold phase of AMO is comparable to that of the long-term and seasonal cycles, as previously reported. However, the response is significantly smaller than the climatic average under the warm phase of AMO. The significant difference in the response of the HC to SST between warm and cold AMO phases are mainly due to differences effects of the cold and warm phases of AMO on SST within the Indo-Pacific warm pool (IPWP). In the AMO warm phase, the cooling amplitudes of SST in tropical IPWP region are different between the the northern and southern hemispheres, which alter the equatorial asymmetric component of the tropical SST increase, and then contributing to the weakening of the response ratio of Hadley circulation to different meridional structure of tropical SST in the AMO warm phase. In the AMO cold phase, the cooling amplitudes of SST in tropical IPWP region are same between the the northern and southern hemispheres, which alter the response ratio of Hadley circulation to different meridional structure of tropical SST is comparable to the ratio of climate averages. The results can be further confirmed by other atmospheric reanalysis data.

    Finally, the capability of the models from the phase 6 of the Coupled Model Intercomparison Project (CMIP6) to simulate the relationship between the HC to different tropical SST meridional structures in warm and cold phases of AMO is evaluated. The results show that the spatial distribution characteristics of the meridional structure of AMO, HC and tropical SST are well simulated in all models. As for the dominant modes, we also found that most models captured the spatial structures of the principal mode of Hadley circulation and tropical SST meridional structure well in the cold and warm phases of AMO. The differences in the responses of HC and the meridional structure of tropical SST in cold and warm phases of AMO are assessed. Significant differences are found in the capability of models to simulate the responses. The models which can well simulate the difference between the meridional structure of tropical SST and atmospheric circulation in the AMO warm and cold phases mainly because it can simulate the asymmetric effect of the cold and warm phases of AMO in tropical IPWP. The results show that the modulation effect of AMO on the tropical air-sea interaction is significant, which is helpful to understand the physical mechanism of the anomalous tropical sea-air interaction.