2021年3月大气环流和天气分析

Analysis of the March 2021 Atmospheric Circulation and Weather

2021年3月大气环流呈双极型分布,中高纬环流为三波型,东亚大槽偏弱,西太平洋副热带高压强度与常年相当。3月全国平均气温为6.6℃,较常年同期(4.1℃)偏高2.5℃,为1961年以来同期第二高。全国降水量为27.8 mm,较常年同期(29.5 mm)偏少6%。本月有3次大范围沙尘天气过程,较常年偏强偏多,其中13—18日为近十年我国最强沙尘天气过程。强对流天气偏少,仅月底在长江流域发生一次强对流天气过程。月内冷空气偏弱,仅于15—17日发生一次中等强度冷空气过程。云南等地干旱持续,华南干旱开始发展。

The main characteristics of the general atmospheric circulation in March 2021 are as follows.There were two polar vortex centers in the Northern Hemisphere,the 500 hPa geopotential height presented the distribution of a three wave pattern in the mid high latitude of Northern Hemisphere.The strength of Western Pacific subtropical high was closed to that in normal years,and the south branch though was a little weaker.The national average temperature in March was 6.6℃,2.5℃higher than the normal(4.1℃)and recorded the second highest in the same period since 1961.The monthly mean precipitation amount was 27.8 mm,6%less than in normal period(29.5 mm).There were three large scale sand dust weather processes in March,which were more and stronger than the usual,of which the sand dust weather in 13-18 was the strongest sand dust weather process in the past 10 years.A severe convective weather process occurred in the Yangtze River Basin at the end of the month,causing severe weather such as hail and thunderstorm.During this month,cold airs were weak,and only one moderate cold wave process appeared in 15-17.The droughts continued in Yunnan Province,droughts appeared and developed in South China.