1981年8～9月黄河上游强连阴雨期水汽输送分析

Analysis of Water Vapour Transport in the Upper Yellow River during Continuously Heavy Rain of August and September 1981

对黄河上游兰州以上区域１９８１年８～９月强连阴雨期主要降水时段水汽输送的计算和分析表明，这次降雨的水汽来自孟加拉湾，由５００ｈＰａ低槽前的西南气流输送水汽；降雨区内水汽的经向辐合是水汽辐合的主要过程，纬向辐散是水汽输出的主要机制，降雨过程中高原地形和垂直运动也明显影响了水汽输送和降雨；该区域水汽净输送量约占实测降雨量的９２％。

hrough the calculation and analysis of water vapour transport over the region aboveLanzhou in the Upper Yellow River during continuously heavy rain in August and September1981, this paper indicates that the water vapour of this rain stemed from the Bay of Bengal andconveyed by the southwest air current front of the pressure at 500hpa. The longitudinal convergence was the principal process of water vapour convergence in this region. The latitudinal divergence was the main mechanism of water vapour outflow. At the same time the plateau topographylifting and the air vertical motion obviously affected the water vapour transport and the rainfall.The percentage of the net water vapour transport to the precipitation is about 92 in the region.