东亚北部地区气温的冬季-冬季再现特征研究

对东亚北部(40—50°N,100—130°E)区域1953—2012年大气温度的冬季-夏季-次年冬季(简称冬季-冬季)的季节变化特征进行了初步研究.结果表明:2008年以来,该区域的气温从低层至高层(1000—400 h Pa)连续三年出现冬季偏冷-夏季偏暖-次年冬季偏冷的典型特征,20世纪50—60年代亦有类似情况;而20世纪90年代则出现了与此相反的冬季偏暖-夏季偏冷-次年冬季偏暖的变化特征.将这种典型的气温季节变化特征定义为一种新的变化机理:冬季-冬季再现(WWR).根据1953—2012年的历年变化情况将这60年划分为四种不同的类型:负(正)冬季-冬季再现(negative/positive WWR)型和负(正)冬季-冬季非再现(negative/positive non-WWR)型.其中,气温表现为WWR型的年份共计23年,出现概率近40%,并且该WWR特征是相对独立于El Nio-南方涛动指数的变化而存在的.对不同类型年份的位势高度场、垂直速度场及其850 h Pa风场进行的合成分析表明:对于WWR型,高层(500 h Pa)至低层(1000 h Pa)的大气内部动力过程具有与气温相匹配的冬季-冬季的再现特征;而non-WWR型则没有出现类似的特征,从而在一定程度验证了WWR存在的可能性.WWR的提出为进一步开展当前全球增暖背景下冬季低温事件的频发提供了一个新的思路.

Characteristics of winter-to-winter recurrence of atmospheric temperature in the northern area of East Asia

Seasonal evolution of atmospheric temperature with winter-summer-the following winter (winter-to-winter) characteristics in the northern area of East Asia (40–50°N, 100–130°E) from 1953 to 2012 has been investigated in this paper. Results indicate that: from 2008 on, the atmospheric temperature in this area had a typical characteristic of cold winter-warm summer-the following cold winter for three consecutive years from the lower layer to the upper layer (1000–400 hPa), and the similar situation also appeared in the period from 1950s to 1960s; however, the opposite variation characteristics of warm winter-cool summer-the following warm winter happened in 1990s. This typical seasonal evolution of atmospheric temperature was defined as a new variation mechanism: winter-to-winter recurrence (WWR). The recent 60 years may be divided into four different types according to the variation of the years from 1953 to 2012: negative (positive) winter-to-winter recurrence (negative/positive WWR) and negative (positive) non winter-to-winter recurrence (negative/positive non-WWR). In the 23 WWR years the probability of occurrence was close to 40%. This WWR characteristic still exists and is independent of the variation of the El Niño southern oscillation index. The synthetic anomalies analysis of geopotential height, vertical speed, and the winter vector at 850 hPa indicates that as for the WWR pattern, the dynamic process of inner atmosphere also has WWR characteristics corresponding to the atmospheric temperature from the lower layer (1000 hPa) to the upper layer (500 hPa) while the non-WWR pattern does not have the similar characters. This study will provide a new idea to further investigate the frequent occurrence of the winter low temperature events on the background of global warming.
Keywords： regional low temperature events correlation coefficient spatial distribution recurrence