晚秋与后冬间欧亚遥相关型波列反相现象探究

围绕1979/1980—2013/2014年晚秋(11月)与后冬(次年1、2月)间欧亚遥相关(EU)型波列关系展开研究,揭示了晚秋与后冬间欧亚遥相关指数存在显著负相关,即二者主要呈反位相变化。对比晚秋与后冬间欧亚遥相关型呈反位相和同位相变化时的环流演变规律发现,反位相变化年晚秋环流异常对后冬有显著的指示意义,而同位相变化年晚秋环流异常对后冬指示意义较弱。就可能的外部成因而言,反位相与同位相变化过程均与北大西洋湍流热通量(NATU)异常有较好的对应关系。具体物理过程表现为:当北大西洋湍流热通量正(负)异常时,有利于北大西洋50°N附近上升(下沉)运动及对流层中低层水汽含量显著增多(减少),相应北大西洋上空高度场乃至整个欧亚遥相关型波列表现为负(正)异常。

An investigation into the phase reversal of EU teleconnections from late autumn to the late winter

The relationship between the EU pattern in late autumn (November) and late winter (the following January and February) for 1979/1980-2013/2014 are discussed in this paper. It is shown that significant negative correlation exists between the late autumn and the late winter EU teleconnection indices. When we compare the circulation evolutionary features between out-of-phase and in-phase processes of EU pattern from the late autumn to the late winter, it is shown that the late autumn circulation anomalies in out-of-phase years have significant implications on the late winter, while the implications are weak in in-phase years. The circulation evolutionary features of in-phase and out-of-phase processes are both closely related to North Atlantic turbulent heat flux (NATU). The specific physical process is that the vertical movements and moisture content in low and middle levels of the troposphere over North Atlantic at about 50°N both increase (decrease) in NATU positive (negative) anomalies, which corresponds to negative (positive) anomalies of geopotential height over North Atlantic and even negative (positive) EU pattern.