2017年4月大气环流和天气分析

摘要

2017年4月大气环流的主要特征是极涡呈偶极型分布,强度偏弱,中高纬环流呈4波型分布,西太平洋副热带高压强度较常年偏强,南支槽强度与常年相当.4月全国平均气温为12.0℃,较常年同期偏高1.0℃;全国平均降水量为44.0 mm,较常年同期偏少2％.月内出现1次全国大范围较强冷空气过程;南方多降水天气,共出现3次区域性暴雨天气;北方出现2次扬沙天气;多省(区、市)局地遭遇风雹灾害.%The main characteristics of the general atmospheric circulation in April 2017 are as follows.Double polar vortex centers existed in the Northern Hemisphere,but weaker than usual.The circulation in Eurasian middle-high latitude showed a four-wave pattern.The strength of Western Pacific subtropical high is stronger than that in normal years.While the south branch trough was almost equal to normal.The monthly mean temperature was 12.0℃,1.0℃ higher than normal,and the monthly mean precipitation amount was 44.0 mm,which was 2％ less than normal.One nationwide strong cold air process happened in this month.There were more precipitation weather events in southern China in this month,with three regional rainstorm processes seen.In addition,two blowing sand weather events happened in the northern China and hail disaster attacked some places of many provinces.