2016年汛期黄河流域雨水情特点及气象成因

Precipitation and Runoff Characteristics and Meteorological Causes of the Yellow River Basin in the Flood Season of 2016

2016年汛期黄河流域雨水情的主要特点是:降水量偏多,降水时空分布极不均匀,径流量偏少,主汛期7—8月多分散性局地暴雨,部分支流发生了多年未见的较大洪水,黄河干流未发生编号洪水。6月受西风带低压槽影响,流域大部地区降水量偏多;7月西风带短波槽活动频繁,副高强度偏强、西伸脊点偏西,降水量整体偏多;8月流域南部地区受大陆高压控制,副高强度弱,西伸脊点偏东,降水主要位于兰州—托克托区间和山陕区间北部,其余大部降水量偏少;9月受巴尔喀什湖至贝加尔湖高压脊前西北气流影响,黄河流域降水量整体偏少;10月黄河流域处于宽广低压区底部,同时副高强度偏强、西伸脊点偏西,受西风带系统和副高共同影响,流域降水量异常偏多。汛期在我国南海和西北太平洋面上热带气旋生成个数接近常年,登陆个数偏多,未对黄河流域降水产生直接影响。

More rainfall and uneven temporal-spatial distribution than that of normal annual were the main characteristics of precipitation in the Yellow River basin during flood season( from June to October) in 2016,meanwhile,multiple decentralized local rainstorms occurred in July and August.Otherwise,there were a few large floods in some tributaries but no serial number flood happened in the mainstream.The different features of each month were as follows: in June,the precipitation amount in most areas of the Yellow River basin was above the normal due to the influence of the westerly trough.In July,the short wave trough activities in westerlies were frequent and the west Pacific subtropical high strengthened and extended westward,hereby,the rainfall wholly increased.In August,the high pressure controlled the southern part of the Yellow River basin.At the same time,the west Pacific subtropical high was weak and located eastward,then the rainfall was mainly located in the Lanzhou-Togtoh area and the northern part of Shanxi-Shaanxi area.In September,the precipitation was less than normal in the whole basin affected by northwest air current before the high-pressure ridge from Balkhash to Baikal Lake.In October,the precipitation was much more than that of mean annual because the entire basin was under the broad low-pressure area and affected by the westerly belt and the subtropical high was strong and extended westward.There were a couple of tropical cyclones as usual produced in the South China Sea and the northwest Pacific Ocean.Actuarially they didn't affect the precipitation of the Yellow River basin in spite of a greater number of landfalls.