西北太平洋低空环流与海温异常关系的季节性差异

通过资料分析与数值模拟研究了西北太平洋低空环流特征及其与海面温度（SST）异常关系的季节性差异，得到如下结论：1）西北太平洋低空环流的空间尺度和位置在春季和夏季存在明显差异，从春季到夏季，异常环流范围缩小且中心位置向西北偏移；2）西北太平洋低空环流与西北太平洋局地海温的相互作用存在季节差异，春季西北太平洋冷海温与上空反气旋异常之间存在相互作用，而夏季则以大气影响海洋为主，异常的反气旋/气旋可以加热/冷却其下垫面的海温，大气超前3～4 d影响海洋；3）夏季异常反气旋环流（WNPAC）的维持主要来自非局地海温异常（北印度洋暖海温与中太平洋冷海温异常）的强迫，这两个海区对WNPAC的影响也存在季节性差异，北印度洋的影响主要体现在晚春至盛夏，而中太平洋则主要在晚夏发挥作用。

Seasonal differences in correlations between low-level circulation and SST anomalies over western North Pacific

Based on reanalysis data and numerical simulation, the meteorological characteristics of the lower circulation over western North Pacific and the seasonal differences in correlations between them and sea surface temperature (SST) anomalies are analyzed. The results are summarized as follows. 1) The spatial scale and the location of the anomalous anticyclone/cyclone over western North Pacific are different in spring and summer. From spring to summer, the anomalous circulation shrinks in spatial scale and its center shifts towards the northwest. 2) There are seasonal differences in the interactions between low-level circulation and local SST over western North Pacific. In spring, cold SST interacts with the upper-level anticyclone over western North Pacific; whereas in summer the influence of the atmosphere on the ocean dominates and anomalous anticyclone/cyclone can heat/cool the SST with a time lead of 3-4 days. 3) The maintenance of anomalous western North Pacific anticyclone (WNPAC) in summer is mainly attributed to the forcing of nonlocal SST (the North Indian Ocean warming and central Pacific cooling). The influences of the two factors on WNPAC also has seasonal differences. The North Indian Ocean SSTs mainly act from May to July, while the central Pacific SSTs act mainly in late summer.