中文摘要：

利用Hadley中心提供的逐月海温资料、ERA-Interim再分析资料以及NOAA（National Oceanic and Atmospheric Administration）的逐月向外长波辐射（OLR）资料探讨了1979-2011年夏季青藏高原＂湿池＂的水汽含量与前期印度洋海温异常的关系,并对可能的原因进行了分析。结果表明,夏季青藏高原水汽（去趋势）EOF第二模态与前期印度洋海温存在密切的正相关,前期3-4月关键区（5°S-20°N,45°E-75°E）的海温异常可以作为夏季高原水汽的预测信号。在暖水年,赤道附近显著的东风异常对夏季高原水汽输送起到了至关重要的作用。500 hPa上副热带高压显著增强并西移,600 hPa上赤道附近为显著的异常东风,将水汽从西太平洋、南海、孟加拉湾向西输送到印度半岛,并在异常反气旋环流西侧的南风作用下,将水汽带向青藏高原。高层风场上,西太平洋地区辐合,青藏高原上空辐散。以上环流形势表明暖水年夏季青藏高原水汽偏多;冷水年则相反。就影响机制而言,前期春季印度洋海温显著偏暖,引起其上空异常的对流上升运动,驱动异常沃克环流从春到夏显著维持,副热带高压的季节性北跳和异常增强西移,有利于赤道东风异常的增强和西移,并经过水汽输送通道将水汽带向青藏高原上空。

英文摘要：

Using SST （sea surface temperature） data from the Hadley Center, ERA-Interim reanalysis data, and OLR data from NOAA, the relationship between the summer water vapor content over the Tibetan Plateau moist pool and the preceding SST anomalies in the Indian Ocean during 1979-2011 and its possible reasons are studied. The results show that the second leading EOF mode of the detrended water vapor content in summer over the Tibetan Plateau moist pool is positively related to SST anomalies over the key area （5°S-20°N, 45°E-75°E） in March and April, thus SST over this key area can be regarded as a precursor of the summer water vapor content. In warm years, the significant easterly anomalies near the equator play a crucial role in the transport of water vapor. The subtropical high in the western Pacific strengthens and moves westward at 500 hPa. At 600 hPa, the significant easterly anomalies are favorable for water vapor transport from the western Pacific, the South China Sea and the Bay of Bengal to India. Under the influence of southerly winds on the western flank of the anticyclone, large amounts of water vapor are transported to the Tibetan Plateau. There is divergence over the Tibetan Plateau and convergence over the western Pacific in the upper troposphere. The above anomalous circulation indicates that the summer water vapor content is much higher over the Tibetan Plateau moist pool in warm years than in cold years, and vice versa. As far as the mechanism is concerned, the significant warm SST anomalies in Indian Ocean can induce anomalous convective updrafts at the springtime, and the anomalous Walker circulation can maintain from the spring to summer. As the WPSH （western Pacific subtropical high） moves northward seasonally with anomalous intensification and westward expansion, equatorial easterly anomalies enhance and move westward as well, which eventually bring more water vapor to the Tibetan Plateau through the above transport path.