山东夏季极端降水时空分布及环流特征分析

本文利用2000-2018年山东省大气监测自动站的降水观测资料以及美国国家环境预报中心与美国国家大气研究中心(NCAR/NCEP)再分析的高空月平均资料、降水月平均资料以及逐日降水资料,分析了不同季节山东省极端降水的时空分布的基本特征,以及异常大气环流对极端降水的影响。结果表明,极端降水对山东降水的影响主要集中在夏季,山东省的东南沿海地区表现更为明显。在500hPa上,极端降水次数偏多季的环流形势表现为AO负位相,在50°N的中纬度西风上波动较为显著,降水概率随之增大。根据极端降水持续时间,将极端降水分为第一类和第二类极端降水,若200hPa上南亚高压偏东,500hPa上副高西伸,中纬度西风带的槽脊振幅明显偏大;同时,在850hPa上,高纬度波长较长,有利于冷空气直接南下和暖湿的水汽输送带交汇于山东省上空,则有利于产生第一类极端降水,反之,则易产生第二类极端降水。

Analysisof Spatial-Temporal Distribution of Extreme Precipitation in Summer in Shandong Province

The basic characteristics of spatial and temporal distribution of extreme precipitation in different seasons and the influence of the abnormal atmospheric circulation on extreme precipitation in Shandong Province are explored using daily precipitation data of atmospheric automatic monitoring station in the province and the reanalysis data of NCAR/NCEP from 2000 to 2018.The results show that the extreme precipitation in Shandong is mainly concentrated in summer and is more obvious in southeastern coastal areas of the province.At 500 hPa the circulation situation always shows AO negative phase when extreme precipitation happened more frequently.The fluctuation of the mid-latitude(around 50°N)westerly is significant and then the precipitation probability increases.The extreme precipitation is divided into two types according to the duration time.The South Asia high is on the east side at 200 hPa,the subtropical anticyclone at the 500 hPa is extended to the west side and the amplitude of the mid-latitude westerly belt is obviously larger.At 850 hPa,the longer wavelength of high latitudes leads to the cold air to meet the warm water vapor transport belts in the upper part of the Shandong Province,which is conducive to the first type of extreme precipitation.On the contrary,they are more likely to produce the second type of extreme precipitation.