2011年1月大气环流和天气分析

Analysis of the January 2011 Atmospheric Circulation and Weather

2011年1月大气环流主要特征如下:北半球极涡中心位于北美北部,强度比常年同期偏弱。中高纬度地区环流呈现三波型分布,东亚大槽、北美槽强度偏弱,西欧槽接近常年同期,东亚锋区明显南压。南支槽位于90°E附近,强度与常年相当。西北太平洋副热带高压明显偏弱。1月主要气候特点:全国平均气温为-8.3℃,比常年同期(-5.9℃)偏低2.4℃,全国平均降水量为8.2mm,比常年同期(12.1mm)偏少3.9mm。华北、黄淮等地区干旱持续发展,冷空气活动频繁,南方雨雪冰冻灾害严重。月内有3次中等强度冷空气及6次降水过程。

The following are the main characteristics of the atmospheric circulation in January 2011.The polar vortex was located to the North America in the Northern Hemisphere.The circulation presented a three-wave pattern in middle-high latitudes.The East Asia and the North America major troughs were weaker than the troughs in average conditions,and the European trough was stronger.The frontal zone in East Asia was further south than normal.The south branch trough was located at 90°E nearby and its intensity was equivalent to normal.The subtropical high in Northwest Pacific was equivalent weaker than normal obviously.The average temperature（—8.3℃） was 2.4℃less than the normal years and the average precipitation（8.2 mm） was 3.9 mm less than the normal years.The drought conditions in North China and Huanghuai area,etc.have been more serious.The active cold air currents resulted in severe freezing rain and snow disasters.There were three cold air processes and six rainfall processes.