2017年1月大气环流和天气分析

Analysis of the January 2017 Atmospheric Circulation and Weather

2017年1月大气环流主要特征如下:北半球极涡呈绕极型分布,中心气压较常年偏低,欧亚中高纬度环流呈两槽一脊型;南支槽强度与常年接近,平均位置位于90°E以西附近,副热带高压较常年接近。1月,全国平均降水量为12.4 mm,较常年同期偏少6%。全国平均气温为-3.4℃,较常年同期(-5.0℃)偏高1.6℃,为1961年以来历史同期第三高值。月内,我国出现主要冷空气过程、主要降水过程以及雾-霾天气过程各2次,其中2016年12月30日至2017年1月6日雾-霾天气过程是1月范围最广、持续时间最长、强度最强的雾-霾天气过程。

The main characteristics of the general atmospheric circulation in January 2017 are as follows. There was one polar vortex center in the Northern Hemisphere with the stronger strength than normal year. The circulation presented the trough-ridge-trough pattern in middle-high latitudes. The south branch was as strong as normal, located near the west of 90~E averagely. The subtropical high also had the same strength as usual. In addition, the monthly mean precipitation is 12.4 mm, 6% less than normal and mean temperature is --3.4~C, 1.6~C higher than normal （--5.0~C）, which is the third high value for the corre- sponding period since 1961. There were two cold air processes, two major rainfall processes and two large-scale fog-haze weather processes during this month. Among them the fog-haze event from 30 December 2016 to 6 January 2017 was characterized by the most extensive, the longest and the most intensive fog-haze weather in January.