亚洲夏季风活动激发北半球大气遥相关的物理机制探讨 II.最优强迫模及其响应

Mechanisms of the atmospheric Teleconnection Associated with the Activity of the Asian Summer Monsoon Part II: Optimal Forcing and Atmospheric Responses

利用最近发展的完备正规强迫模的动力学方法， 对亚洲夏季风活动激发北半球大气遥相关的外部物理机制进行了探讨。结果表明， 北半球夏季亚洲季风区是外强迫最敏感区域之一， 最优强迫模与亚洲季风区季内时间尺度对流活动的结构特征相似， 而且北半球大气对最优强迫模的响应与滞后于强季风候的环流异常型结构一致， 由此可以认为， 亚洲夏季风活动造成的热状况变化也是导致北半球大气遥相关的重要物理原因。

The external mechanism by which the activity of the Asian summer monsoon (ASM) develops the atmospheric teleconnection is investigated by using the methods of the complete orthonormal forcing mode. It is found that, during boreal summe the most optimal forcing modes are mainly centered over the ASM region, and exhibiting similar features to the anomalous OLR related to the activity of the ASM. Moreover, the atmospheric responses to the most optimal forcing bear much resemblance to the anomalous circulation patterns lagging behind the strong monsoon pentads. These results suggest that, as an optimal forcing, the thermal variation in the ASM region can lead to the atmospheric teleconnection over the Northern Hemisphere.