来自印度季风区的水汽输送与东亚上空水汽输送和中国夏季降水的关系

摘要

A diagnostic study is made to investigate the relationship between water vapor transport from Indian rnmonsoon and that over East Asia in Northern summer. It is found that water vapor transport from Indian rnmonsoon is inverse to that over East Asia. More (less) Indian monsoon water vapor transport corresponds rnto less (more) water vapor transport over East Asia and less (more) rainfall in the middle and lower reaches rnof the Yangtze River valley. The Indian summer monsoon water vapor transport is closely related to the inrntensity of the western Pacific subtropical high in its southwestern part. The stronger (weaker) the Indian sumrnmer monsoon water vapor transport, the weaker (stronger) the western Pacific subtropical high in its rnsouthwestern part, which leads to less (more) water vapor transport to East Asia, and thus less (more) rainrnfall in the middle and lower reaches of the Yangtze River valley. Analysis of the out-going longwave radiarntion anomalies suggests that the convective heating anomalies over the Indian Ocean may have significant rnimpact not only on the Indian monsoon, but also on the East Asian monsoon.%诊断分析了北半球夏季来自印度季风的水汽输送与东亚上空水汽输送的关系，发现二者之间具有反相变化的特征。印度季风水汽输送偏强(偏弱)时，东亚上空的水汽输送偏弱(偏强)，长江中下游降水偏少(偏多)。印度夏季风水汽输送与西太平洋副热带高压强度有显著的相关关系，印度季风水汽输送偏强(偏弱)时，西太平洋副热带高压强度偏弱(偏强)，由此导致副高西侧东亚上空向北的水汽输送减弱(增强)，使得长江中下游降水偏少(偏多)。对反映热带对流活动的外逸长波辐射(OLR)的分析表明，印度洋上空的对流加热异常不仅能够显著地影响印度季风，也可能对东亚季风产生直接的影响。