2012年7—8月兰州以上来水特点及气象分析

Analysis of the Meteorological Factors and Runoff Characteristics of River Reaches above Lanzhou of the Yellow River During July and August of 2012

2012年7—8月黄河兰州以上地区降水普遍偏多,各代表站平均降水量为225 mm,较常年同期偏多36%。受降水影响,黄河上游来水异常偏多,唐乃亥站7—8月总径流量达130亿m3,为有记录以来最大值,兰州站7月30日出现自1986年以来最大洪峰流量。经分析,2012年7—8月有利于兰州以上区域降水的大气环流特征主要有印缅槽指数偏低、青藏高原高度场指数偏低、西太平洋副热带高压脊线位置明显偏北、热带对流十分活跃等。

The precipitation in the Yellow River area above Lanzhou was general too much during July and August in 2012.The mean rainfall of each representative stations was 225 mm and 36% more than the same period of normal years.The total runoff of July and August at Tangnaihai Station reached the historical record of 13 billion m3,and the flood peak at Lanzhou Station reached the maximum value on the 30th of July since 1986.The analysis shows that the atmospheric circulation for more rainfall during July and August of 2012 has some advantaging characteristics,such as low Indices of India-Burma trough and Qinghai-Tibet Plateau height field,the obvious north position of high ridge of Western Pacific subtropical,active tropical convection and so on.