夏季索马里急流的建立及其影响机制

定义了夏季索马里急流（SSMJ）的建立指数，从而确定了1948--2002年的SSMJ建立日期，并以此为基础研究了SSMJ建立过程以及前冬海陆热力异常和冬季风异常对其建立早晚的影响。结果表明：SSMJ的建立是亚洲季风爆发的最早信号；其建立过程受到马斯克林高压、中非低压以及阿拉伯高压等非洲-印度洋系统的影响，而印度低压的发展有利于SSMJ越过赤道后向东转向；夏季索马里急流建立时间的年际变化反映了北半球冬季海陆热力差异的年际异常；强（弱）东亚冬季风时，次年春季SSMJ建立偏迟（早）。

Onset Process of Summer Somali Jet and the Possible Influenced Mechanism

The Summer Somali Jet(SSMJ) onset dates during the period from 1948 to 2002 are decided by a defined index for SSMJ onset.Then the processes of SSMJ onset and the influence of anomalies of the winter land-sea surface temperature and the East Asia winter monsoon are analyzed in this paper.The results show that the onset of SSMJ is the earliest signal of the Asia summer monsoon;the onset of SSMJ is caused by the African-Indian Ocean System,including Mascarene High,Middle African Low and Arabian High;the developing Indian Low can force SSMJ eastward after crossing equator.The interannual anomaly of SSMJ onset dates reflects the interannual anomaly of prophase winter temperature difference between land and sea.When the winter monsoon is stronger(weaker),the onset of SSMJ is later(earlier) in the coming spring.