滇中引水工程主要受水区水汽输送时空变化

基于ERA-Interim再分析资料,以滇中引水工程主要受水区为研究对象,计算了受水区上空21 a水汽输送通量及水汽输送通量散度,并对其水汽输送、水汽辐合与水汽辐散等特征进行分析,研究其水汽输送时空变化特征。结果表明:研究区年平均水汽输送由西北至东南方向逐渐增加,并以纬向输送为主;水汽来源随季节移动,研究区夏季受西南风控制,水汽输送强度明显小于其他3个季节;5—7月份,研究区水汽输送强度逐渐衰减,7月份,研究区850 hPa气压层南部地区存在水汽辐合中心,450 hPa气压层西南部为水汽辐散带,在西南部易于形成降水。

Temporal and Spatial Variation of Water Vapor Transport over the Main Water-receiving Area of Water Diversion Project in Central Yunnan Province

According to the ERA-Interim data, the 21-year water vapor transport flux and divergence over the main water-receiving area of the water diversion project in central Yunnan Province were calculated. The spatial-temporal characteristics of water vapor transport, convergence and divergence in the studied area were also analyzed. Results demonstrate that the annual average water vapor transport in the studied area gradually increases from the northwest to the southeast, and is dominated by latitudinal transport. The source of water vapor moves with the seasons and is controlled by southwest wind in summer. The intensity of water vapor transport in the studied area in summer is significantly lower than that in the other three seasons. From May to July, the intensity of water vapor transport shows a gradual decline. In July, a water vapor convergence center emerges in the south of the studied area on the 850 hPa barosphere and a water vapor divergent zone in the southwest on the 450 hPa barosphere, beneficial for the formation of precipitation in the southwest.