东亚冬季风对秋、冬季SSTA响应的数值试验

Numerical Experiments on the Responses of East Asian Winter Monsoon to Autumn and Winter SSTA

摘要:

利用NCARCCM2模式,通过设计多组数值试验方案,研究了东亚冬季风对赤道中东太平洋、中纬度太平洋秋、冬季SSTA的响应。模拟结果表明,东亚冬季风对秋、冬季太平洋SSTA均存在一定的响应,但冬季风对SSTA的响应存在显著的季节和海域差异,并表现出不同的异常响应形态。东亚冬季风对秋季SSTA的显著响应区域位于中纬度太平洋地区,该区域的SST的持续异常,可以引起欧亚、北美地区冬季大气环流的异常,并伴随有明显的EU型和PNA型波列特征,秋季中纬度太平洋SST持续异常偏冷(暖),能够引起有利于强(弱)东亚冬季风的环流异常。而冬季风对冬季SSTA的响应则为赤道中东太平洋和中纬度太平洋SSTA共同作用的结果,在两个区域SSTA的同时强迫下,大气环流表现出类似PNA及WP型波列分布的异常响应特征,赤道中东太平洋的正(负)的SSTA及中纬度太平洋负(正)的SSTA,将导致弱(强)冬季风的发生。

Abstract:

Numerical experiments are designed to investigate the responses of East Asian winter monsoon(EAWM) to autumn/winter sea surface temperature anomaly(SSTA) in the equatorial east central and mid latitude Pacific by using NCAR CCM2.Results show that EAWM responds to the winter/autumn SSTA in both the mid latitude and equatorial east central Pacific to a certain extent,but the anomalous characteristics of the atmospheric response to SSTA are various with the season and the sea area where the SSTA occurs.In autumn,the significant response of EAWM to SSTA occurs in the mid latitude Pacific.The persistent autumn SSTA in the mid latitude Pacific can lead to the anomalous general circulation of atmosphere over Eurasian Continent and North America,inducing the atmospheric EU and PNA wave train patterns.The cooler(warmer) autumn SST in the mid latitude Pacific is favorable to the occurrence of a stronger(weaker) EAWM.But in winter,EAWM is affected by SSTAs in both the equatorial east and central Pacific and the mid latitude Pacific.The forcing from the SSTA over those two regions results in the anomaly of winter general circulation accompanied with the PNA and WP wave train patterns.As a result,the positive(negative) SSTA in the east and central Pacific and the negative(positive) SSTA in the mid latitude Pacific are favorable to the occurrence of a weaker(stronger) EAWM.