2015年1月大气环流和天气分析

Analysis of the January 2015 Atmospheric Circulation and Weather

2015年1月大气环流主要特征为:北半球极涡呈偶极型分布,中心气压均较常年偏低。欧亚中高纬环流呈三波型,以纬向环流为主;西太平洋副热带高压和南支槽的强度接近常年平均水平。1月全国平均气温为-3.1℃,较常年同期(-5.0℃)偏高1.9℃,为1961年以来同期最高。全国平均降水量14.4 mm,较常年同期(13.2 mm)偏多气候中心原数据为9.0,但计算为9.1,但分布极不均匀,西南地区、西北地区和华南南部降水偏多,而华北至江南一带则明显偏少,北京等地几乎无降水。月内仅在上旬出现了1次全国范围中等强度冷空气过程,而降水过程有5次。上旬后期,云南等地出现了创历史极值的强雨雪天气,气象干旱得到有效缓解。月末中东部地区出现入冬以来最大范围雨雪过程,贵州等地出现冻雨。中东部月内共出现3次大范围雾-霾天气。

The main characteristics of general atmospheric circulation in January 2015 are as follows:There were two polar vortex centers in the Northern Hemisphere with weaker strength than normal years.The circulation in Eurasian mid-high latitudes showed a three-wave pattern and mainly performed in zonal circulation.The strength of Western Pacific subtropical high and the south branch trough were near climatological normal.The monthly mean temperature was(-3.1℃) higher than normal(-5.0℃) by 1.9℃,which is the highest in record since 1961.The monthly mean precipitation was up to 14.4 mm,9.1% more than normal(13.2 mm).However,the distribution of precipitation was quite uneven during the study period.The amount was more than normal in Southwest China,Northwest China and the south of South China.In contrast,it was significantly less than normal from North China to Jiangnan Region and there was almost no precipitation in Beijing and some other places.There was only one cold air process nationwide in this month which occurred in the first dekad,while five rainfall processes happened during the same time.At the late stage of first dekad,record-breaking heavy rain and snow event occurred in Yunnan Province and the meteorological drought was significantly alleviated.At the end of this month,large-scale cryogenic rain and snow weather dominated the central and eastern part of China,which was the first time since this winter,and freezing rain was seen in Guizhou Province.Meanwhile,three wide-range fog and haze processes occurred in the central and eastern part of China.