Precursory atmospheric teleconnection patterns for strong Siberian High events

Abstract

Based on Japanese 55-year daily reanalysis data, the present study reveals that a strong Siberian high (SH) is preceded by three teleconnection patterns—namely, the Scandinavian (SCA) pattern, western Pacific (WP) pattern, and Polar/Eurasian (POL) pattern. Accordingly, strong SH events are classified into three types. Composite results show that there are evident differences among the three types in their typical circulation characteristics and impacts on surface air temperature (SAT) in East Asia. The SCA type is characterized by a wave-train anomaly over mid- and high-latitude Eurasia, while the WP type is characterized by a western expansion of circulation anomalies from the downstream western North Pacific/Far East. The significant signal of the POL type is a gradual southward movement of anticyclonic anomalies from the North Pole. In terms of the impact on SAT in East Asia, the SCA type and POL type are similar since they can cause a wide range of cold anomalies in East Asia. However, the cold anomalies caused by the POL type in northern China show significant signals earlier. The WP type causes only modest cold anomalies over northern and eastern China, but the persistence of SAT anomalies is obvious.摘要本文利用日本55年逐日再分析资料, 发现在SH异常增强前, 有三种不同的大气遥相关型前兆信号, 即斯堪的纳维亚 (SCA) 型, 西太平洋 (WP) 型, 极地-欧亚 (POL) 型. 据此, 本文将异常增强的SH分为对应的三类事件. 合成结果表明, 三类事件在典型环流特征和对东亚气温的影响上存在着明显的不同. 具体而言, SCA类事件主要表现为在欧亚中高纬度上自西向东的波列异常, WP类事件表现为环流异常自下游太平洋/俄罗斯远东地区向西发展的特征, POL型事件的显著信号则来源于自极区向南移动的反气旋式环流异常. 在对东亚地表气温的影响上, SCA类与POL类事件类似, 它们均可造成大范围的低温异常. 而WP类仅在我国北方和东部地区造成强度较弱的地表气温异常, 但该异常的持续性特征较明显.