中文摘要：

通过与探空站资料比较,在分析NCEP I、NCEP II和ECMWF再分析资料整层相对湿度变化趋势和显著性水平的基础上,应用NCEP I再分析资料和1960-2010年气象台站观测资料,研究了祁连山地区过去51 a来空中水汽输送变化特征,分析了水汽输送发生变化的原因,并探讨了该地区夏季降水与东亚季风、南亚季风、南海季风、西风带和副热带高压等季风指数之间的关系.结果表明：祁连山地区的空中整层水汽含量在1960年代下降趋势明显,之后近40多年基本保持稳定,总体表现为下降趋势.水汽净收支整体表现为明显的下降趋势,说明过境水汽留在祁连山地区的数量在减少.其中,经向水汽整体表现为北风输送,为＂＋＂值,对水汽净收支的贡献为＂正＂,呈下降趋势;纬向水汽整体表现为西风输送,为＂-＂值,说明对水汽净收支的贡献为＂负＂,表现出的下降趋势说明纬向流失的水汽在减少.进一步分析显示,祁连山地区水汽净收支减少的直接原因是由风速减小导致流入本区域的水汽输送量减少引起的.地表到300 hPa平均风速显示,纬向风速率1990年代比1960年代减小了13.2%,经向风速率1990年代比1960年代减小了10.5%.夏季降水量与各季风指数的相关性表明,祁连山西部、中部和东部降水均未与各季风指数有较好的相关关系,该地区特殊的地形作用和环流条件及该研究关注的季节和时间尺度是产生这一结论的主要原因.

英文摘要：

In this paper,reanalysis data（ NCEP I,NCEP II and ECM WF） w ere comparing w ith radiosonde data. NCEP I reanalysis data,together with observational meteorological data,were used to study the characteristics of water vapor transport over the Qilian Mountains for the period of 1960-2010. The reason of water vapor transport changing was analyzed. The relationships between summer precipitation and the East Asian Monsoon,the South Asian Monsoon,South China Sea Monsoon,zonal wind and subtropical anticyclone were also investigated. The results show that the precipitable water showed an obvious downward trend in the 1960 s,and then has basically remained stable from the 1970 s to present. As a whole,it is a decline trend. The remained water vapor has decreased and the net water balance has obviously gone down. Hereinto,the whole meridional water vapor transport,i. e.,north wind transport,has appeared positive value,resulting in positive contribution to net moisture budget. The whole zonal water vapor transport,i. e.,westerly transport,has appeared negative value,resulting in negative contribution to net moisture budget. Moreover,wind speed decreasing has resulted directly in water vapor transport decreasing and has further decreased net moisture budget. The change in w ind speed averaged from ground surface to 300 hPa height shows that zonal wind speed decreased by 13. 2% in the 1990 s as compared to that in the 1960 s,and meridional wind speed decreased by 10. 5%. The correlation coefficients between summer precipitation and summer monsoon indices show that the correlations are poor in western part,middle part and eastern part of the Qilian Mountains,which are mainly caused by the effects of special terrain,condition of circulation,researching season and time scale.