两类极区平流层异常增温的特征及其与850hPa温度的关系

采用NCEP/NCAR逐日再分析资料,将冬季极区平流层增温分为两种类型:Ⅰ型和Ⅱ型,并分析了两种类型增温的特征、机制及其与850hPa温度的关系。结果表明,波动强迫的强度和对流层的热量能否向上到达平流层是决定两类平流层异常增温的两个主要因素。Ⅰ型平流层增温期间,对流层也表现出了明显的增温特征,850hPa与平流层温度距平场呈现相当正压结构,极区和中纬度异常表现为反位相的振荡,呈现典型的北极涛动的特征;Ⅱ型平流层异常增温期间,增温异常仅局限在平流层范围内,平流层的中低层与高层呈现反位相的距平分布,850hPa温度距平场呈现无规则的分布特征。

CHARACTERISTICS OF TWO TYPES STRATOSPHERIC WARMING ANOMALY IN POLAR REGION AND THEIR RELATIONS WITH 850 HPA TEMPERATURE

Based on the daily NCEP/NCAR reanalysis data,the winter stratospheric warming anomaly in the polar region are divided into two types,as well as the relationship of the characteristics,mechanisms with the temperature on 850 hPa level are analyzed.Rresults show that the strength of wave forcing and the troposphere heat are two major factors of stratospheric warming anomaly.As typeⅠ,there is obviously trend of increasing temperature in the troposphere and an equivalent barotropic structure in the temperature anomaly field between the stratosphere and troposphere.Meanwhile,there is an inverse phase oscillation between the polar region and the middle latitude region,which shows the typical characteristics of Arctic Oscillation.As typeⅡ,the warming anomaly is confined to the stratosphere,there are opposite anomaly distributions between the mid-lower and upper stratosphere,and the warming anomaly at 850 hPa level which shows irregular distribution.