基于交叉小波分析方法的西太平洋副热带高压年际变率与热带海温及大气环流异常的相关性研究

西太平洋副热带高压的年际变率受热带多个关键海区的海-气相互作用过程调控, 但彼此间的因果关联和影响机制尚不清楚。为揭示西太平洋副热带高压的年际变率与热带海温及大气环流异常之间的内在关联特性, 定义了三个关键海区以及赤道纬向西风区的特征指数, 并分别与西太平洋副热带高压强度、脊线指数进行了交叉小波和相干小波分析。研究发现:西太平洋副热带高压指数存在显著的2~3年和准5年的周期振荡, 20世纪八九十年代后, 由于暖池区海温及赤道纬向西风区的Hadley环流强迫加强, 致使副热带高压特征指数的2~3年周期振荡加强; 从位相关系看, 先是西太平洋副热带高压减弱南撤导致纬向西风加强, 其后影响赤道东太平洋海温升高, 同时暖水向东传, 使赤道中太平洋以及暖池区海温逐渐升高, 在Hadley环流作用下使副高加强北抬。基于上述西太平洋副热带高压的年际变率与热带海温及大气环流异常变化相关性诊断研究, 进一步探讨了造成这种相关性的影响机理和因果关联, 为揭示西太平洋副热带高压年际变率与热带海温及大气环流异常的相关性做探索研究。 

POSSIBLE INFLUENCES OF THE SOLAR CYCLE ON THE ONSET OF SOUTH CHINA SEA SUMMER MONSOON

The interannual variability of the Western Pacific Subtropical High (WPSH) is controlled by the sea-air interaction process in several key tropical sea areas, but the causal relationship and influence mechanism between them are not clear. In order to reveal the relationship between the interannual variability of the WPSH, the tropical SST and atmospheric circulation anomalies, the characteristic indexes of the equatorial zonal westerlies and three key sea areas are defined. The cross wavelet and coherent wavelet analysis are carried out among them with the intensity index and ridge index of the WPSH, respectively. It is found that there are significant 2-3-year and quasi-5-year periodic oscillations in the WPSH index. After 1980s and 1990s, due to forced strengthening of the Hadley circulation in the warm pool area and the equatorial zonal westerly region, the 2-3-year periodic oscillations of the WPSH characteristic index are strengthened. From the perspective of the phase relationship, the weakening of the WPSH first causes the strengthening of the zonal westerly wind, and then affects the rise of the SST in the equatorial east Pacific Ocean with the eastward movement of warm water. The SST in the equatorial central Pacific Ocean and warm pool area gradually increases, and the WPSH strengthens and moves northward under the influence of Hadley circulation. Based on the above diagnostic study on the correlation between the interannual variability of the WPSH and the abnormal changes of the tropical SST and the general circulation, the influencing mechanism and causal correlation are further discussed, revealing the correlation between the interannual variability of the WPSH and the anomalies of the tropical SST and the general circulation.