Interdecadal change in the North Atlantic storm track during boreal summer around the mid-2000s: role of the atmospheric
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Interdecadal change in the North Atlantic storm track during boreal summer around the mid‑2000s: role of the atmospheric internal processes Sai Wang1,2 · Wen Chen1,2 · Shangfeng Chen1,2 · Shuoyi Ding1,3 Received: 19 December 2019 / Accepted: 6 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The first EOF mode (EOF1) of summer storm track activity over the North Atlantic is characterized by a dipole structure, with negative storm track anomalies over the south coast of Greenland extending northeast across Iceland to the Norwegian Sea and positive anomalies over coastal western Europe. This study shows that a significant interdecadal change in the North Atlantic storm track during boreal summer occurred around the mid-2000s. After the mid-2000s, the EOF1 occurs more frequently at its positive phase, which is associated with an interdecadal increase in the geopotential height anomalies around Greenland. On the intra-seasonal timescale, the anticyclonic anomalies around Greenland are crucial for the occurrence of positive EOF1 events via triggering eastward propagating Rossby waves. Therefore, the interdecadal increase in the geopotential height anomalies around Greenland tends to facilitate the occurrence of the positive EOF1 event and is therefore a key driver of the interdecadal change in the summer storm track activity over the North Atlantic. Further analysis indicates that the development of anticyclonic anomalies around Greenland is maintained by the self-interaction among the low- and high-frequency transients themselves. Moreover, the anomalous synoptic eddy activities associated with the change in storm tracks can in turn amplify and maintain the Rossby waves triggered by the anticyclonic anomalies around Greenland in the synoptic-scale eddy feedback process. Keywords North Atlantic storm track · Summer · Interdecadal change · Wave-flow interaction
1 Introduction It is known that the synoptic eddies (i.e., cyclones/anticyclones) have a considerable impact on extratropical weather and short-term climate variability. The local maxima of synoptic eddy activity can be found over the North Pacific and the North Atlantic, which are the so-called North Pacific and North Atlantic storm tracks, respectively (Blackmon 1976; Hoskins and Valdes 1990; Chang and Fu 2000; Chang et al.
* Wen Chen [email protected] 1
Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100190, China
2
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
3
Institute of Atmospheric Sciences, Fudan University, Shanghai, China
2002; Chen et al. 2014). The climate of Europe is strongly influenced by these storms, which track across the North Atlantic from the east coast of North America along the North Atlantic storm track (Wallace et al. 1988; Chang and Yu 1999). As much of the precipitation over Europe arises from extratropical cyclones (Hawcroft et al. 2012; Pfahl and Wernli 2012), ch
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