摘要
Abstract
In respect of the abnormality of atmospheric circulation,the response of the runoff of Huayuankou Station on the Yellow River to global climate change and the atmospheric circulation have been studied by using the runoff observation data at Huayuankou Station and NCEP/NCAR re-analysis data. Results show that:a)both the annual runoff and the main flood season runoff at Huayuankou Station show a significant decreasing trend;b)a climate mutation of runoff occurred in 1986,and the reduction is much more significant after the mutation;c)in case of the main flood season,discriminative features of northern hemisphere circulation can be distinguished as two stages:before and after the mutation. Among them:In the altitude difference field at 500 hPa,stage Ⅰ(1949—1985)shows a more significant meridional circulation while stage Ⅱ(1986—2010)is dominated by zonal circulation;As for the difference of sea level pressure,in stage Ⅰ the low pressure of Mongolia during the major flood period is extraordinarily strong,and summer monsoon gets heavier. On the contrary,in stageⅡthe low pressure of Mongolia during the major flood period decreases significantly,and summer monsoon gets weaker;In the wind difference field at 700 hPa,anomalous southwesterly reaches the Yellow River basin and north China during the major flood period of stage Ⅰ,while in stage Ⅱ,there is anomalous northeasterly from northeast China, north China,middle and lower reaches of the Yellow River basin to Sichuan Province;From latitude-height profiles ,we can conclude that:in stage Ⅰ,there is an anomalous rise in the Huang-Huai area and north China,which is just the opposite from stage Ⅱ.关键词
径流/突变/大气环流异常/花园口/黄河Key words
runoff/mutation/atmospheric circulation anomalies/Huayuankou Station/Yellow River分类
建筑与水利
