热力强迫对澳洲北部越赤道气流强弱变化的影响

采用1980-2004年NCEP／NCAR再分析资料，从影响越赤道气流的大气内、外强迫因子（主要指大气凝结潜热释放及下垫面热力差异）出发，结合诊断分析和数值试验，探讨了强迫因子对澳洲北部由南向北越赤道气流强弱变化的影响。结果表明，冷澳洲大陆有利于强澳高或频繁冷空气活动的形成，通道南部弱下垫面加热有利于弱Walker环流的形成，南海一中南半岛较强海陆热力差异或菲律宾强对流加热有利于通道北部强辐合带的形成，它们都对应澳洲北部由南向北强越赤道气流的形成。弱越赤道气流对应的强迫因子及环流因子的特征则与上述情况相反。

The impacts of thermal forcing on the cross-equatorial flow over North Australia

Using the NCEP/NCAR reanalysis data during 1980-2004, some forcing factors, such as la-tent heat release from condensation and underlaying surface thermal differecence, are defined and their impacts on the south-to-north cross-equatorial flow are studied with diagnosis analysis and numerical simulation. Main conclusions are shown as follows：the cold Australia land always corresponds to strong Australian High or frequent cold air activities, which is favorable for the formation of strong cross-equa-torial flow;the cold underlaying surface to the south of the channel is often accompanied by weak Walker circulation, which is also helpful for the establishment of strong cross-equatorial flow;the warm Indo-China peninsula and cold South China Sea, as well as the strong heat source near the Philippines, all can be associated with strong convergence zone in north hemisphere, which is advantageous for the formation of strong cross-equatorial flow. The features of forcing factors and circulation factors corre- sponding to weak south-to-north cross-equatorial flow are opposite to the above ones.