西北太平洋大气异常反气旋对海平面高度和海洋表层环流的影响

Impacts of Northwest Pacific anomalous anticyclone on sea surface height and circulation

利用美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)的风场数据和SODA2.2.4版本的再分析流场和海平面高度数据,采用合成分析的方法研究了1971—2010年伴随印度洋海盆增暖(India ocean basin mode,IOBM)而发生的西北太平洋异常反气旋(Northwest Pacific anomalous anticyclone,NWPAC),以及由其引起的海洋表层环流和海平面高度异常的变化。伴随IOBM所形成的西北太平洋反气旋在夏季时强度最大,并对西北太平洋上层海洋环流和海平面高度异常有显著影响。西北太平洋异常反气旋会引起海洋反气旋环流异常,对应着海面辐合、海平面高度升高。南海上层海洋对西北太平洋大气异常反气旋的响应准同步,而菲律宾以东上层海洋的响应约滞后一个季节,海洋反气旋环流异常在秋季时达到最强,这种延迟可能和该纬度上西传Rossby波对海洋的调整有关。

In this study,we investigate the Northwest Pacific anomalous anticyclone(NWPAC)associated with Indian Ocean warming and its impacts on ocean circulation and sea surface height in the northwest pacific by using the reanalysis wind,current and sea surface height data of National Centers for Environmental Prediction(NCEP)and SODA v2.2.4during the period of1971to2010.Composite results reveal that the NWPAC associated with Indian Ocean warming is the strongestduring the boreal summer and it has significant impacts on the upper-ocean circulation and sea surface height in the NW Pacific.The anticyclonic wind anomaly produces a negative wind stress curl,inducing convergence of sea surface water and the resultant positive sea level anomalies.The effect of NWPAC on the upper-ocean circulation in the South China Sea is synchronous,while its impact on the upper ocean east of the Philippines delays by about one season and peaks in the boreal autumn.This may be attributed to the modulation of westward oceanic Rossby wave.