北太平洋海温异常的空间模态及其与东亚环流异常的关系

Spatial Modes of the Summer SST Anomaly in the North Pacific and Its Relationship with the Circulation Anomaly over East Asia

运用英国气象局全球海温和NCEP/NCAR再分析逐月资料,分析了1979年以来北太平洋夏季海温异常的主要模态,并探讨了海温异常的空间分布与东亚环流异常的关系。结果表明:北太平洋夏季海温主要存在两种模态,当太平洋热带地区西高东低(西低东高),西太平洋到黑潮区海温偏高(低),东南太平洋的海温偏低(高)时,东亚贝加尔湖南侧地区为显著的正(负)高度异常。进一步分析发现这种环流异常与北太平洋西部海温异常引起的辐合辐散有关,北太平洋西部近大陆海域海温异常偏暖(冷),对应上空为异常的上升(下沉)运动,因质量的连续性使贝加尔湖南侧地区低层辐散(辐合)异常,有利于该地区异常反气旋性环流的加强(减弱)。

In terms of the NCEP/NCAR and British Meteorological Office monthly global sea surface temperature data, the dominant spatial modes of summer North Pacific SST anomaly （SSTA） since 1979 are examined. The relationship between the spatial variation of SSTA and East Asian circulation is investigated by the further analysis. Resuits show that there are two dominant modes for the summer North Pacific SSTA. When SST is higher （lower） than normal in the western Pacific from the tropical to Kuroshio region and lower （higher） in the southeastern Pacific, there are remarkable height anomalies to the south of Baikal, which is associated with divergence anomalies resuiting from SSTA in the western Pacific. Anomalous ascending （descending） motions occur when SSTA is positive （negative） in the western Pacific and thereby anomalous descending （ascending） motions appear to the south of Baikal because of quality continuity. And it is helpful for the anticyclone to be enhanced （weaken） there.