北半球冬季各阻塞系统对大范围极端温度异常的单独和协同影响

本文利用1979～2015年ERA-interim逐日再分析资料,对比分析了格陵兰阻高（GB）、大西洋—欧洲阻高（AEB）、乌拉尔山阻高（UB）和北太平洋阻高（NPB）四个阻高系统对年际尺度和天气尺度地面温度及极端冷日的单独和协同影响。结果表明,各阻高与地面温度之间的统计关系十分复杂,同一阻高系统可影响多个地区的温度异常,同一个地区的地面温度一般可受到多个阻高系统的不同影响。通过分离单阻高和多阻高（双阻高、三阻高和四阻高）组合的情形,本文的结果进一步表明,UB对欧亚大陆地面温度的影响最为重要,其次对于欧洲地面温度而言,依次为AEB、GB和NPB;对于亚洲地面温度而言,依次则为GB、NPB和AEB。而NPB对北美大陆温度的影响最为重要,其次为GB和AEB,UB的影响最弱。此外,多阻高协同影响地面温度时,并非线性叠加,而是表现为显著的非线性特征。

The Independent and Coordinative Influences of the Four Blocking Systems in the Northern Hemisphere Winter on the Occurrence of Widespread Extreme Cold Surface Temperature

Based on 1979-2015 ERA-interim daily reanalysis data, this paper analyzes the independent and coordinative effects of four blocking systems (the Greenland blocking, GB; the Atlantic-Europe blocking, AEB; the Ural blocking, UB; the North Pacific blocking, NPB) on surface air temperature (SAT) and extreme cold days on interannual and synoptic scales. The results show that the statistical relationship between the blocking systems and SAT is very complicated. The same blocking system can affect SAT anomalies in many areas. Meanwhile, the SAT in the same area is generally affected by many blocking systems. By separating a single blocking from multiple blockings (double blockings, three blockings and four blockings), it is further demonstrated that the influence of UB on Eurasia SAT is the most important. However, the blocking systems that have secondary impacts on SAT over Europe and Asia are different. AEB, GB and NPB rank next for Europe while GB, NPB and AEB rank next for Asia in order of importance. The blocking system that has the most important influence on the SAT over the North American is NPB, followed by GB and AEB, and the effect of UB is the weakest. In addition, the coordinative effects of multiple blocking systems on SAT are significantly nonlinear instead of a linear superposition.