North Pacific storm track response to the mesoscale SST in a global high-resolution atmospheric model
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North Pacific storm track response to the mesoscale SST in a global high‑resolution atmospheric model Chao Zhang1 · Hailong Liu2,3 · Jinbo Xie2,3 · Pengfei Lin2,3 · Chongyin Li1,2 · Qian Yang2,3 · Jie Song2,3 Received: 3 July 2019 / Accepted: 21 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The response of the North Pacific storm track to the mesoscale sea surface temperature (SST) in winter is investigated via a global high-resolution atmospheric model. A simulation forced by eddy-resolving SST is compared with a simulation in which the mesoscale SST is filtered out. The results show that removing the mesoscale SST could greatly influence the storm track in the free atmosphere, with a significant decrease of approximately 20% in the local region and a southward shift downstream over the eastern North Pacific. Compared with those in previous studies, the responses of the storm track seem to be independent from models. The underlying mechanism is that changes in the boundary layer induced by mesoscale SST lead to convergence at the surface through pressure adjustment, forcing a secondary circulation along Kuroshio and Oyashio confluence region (KOCR). Then the winter mean vertical eddy fluxes are greatly suppressed over KOCR after removing the mesoscale SST, transporting less heat and moisture into the free atmosphere. Furthermore, the response of baroclinicity and baroclinic energy conversion was investigated, which bears much resemblance with the changes of storm track, indicating the important role on the response of storm track to mesoscale SST. Keywords Storm track · Mesoscale SST · Air–sea interaction · CAM4
1 Introduction Storm tracks, known as the particular regions where activities of synoptic-scale atmospheric eddies are vigorous, play a critical role in transporting heat and moisture between subtropics and the mid-latitudes regions, and thus shaping the weather and climate of the Earth (Hoskins and Valdes 1990; Chang et al. 2002). In recent decades, numerous studies have investigated the mechanisms of storm tracks (Lau and Nath 1991; Straus and Shukla 1997; Sampe et al. 2010). * Hailong Liu [email protected] * Chongyin Li [email protected] 1
College of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101, China
2
State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
3
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
The intensity and location of storm tracks can be influenced not only by internal atmospheric processes such as the variations of jet streams (Lee and Kim 2003), low frequency events (Zhang and Held 1999), but also by external oceanic processes such as El Niño and the Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO), the ocean basin scale sea surface temperature (SST) anomalous patterns (Straus and Shuk
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