Role of the Atlantic multidecadal variability in modulating East Asian climate
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Role of the Atlantic multidecadal variability in modulating East Asian climate Paul‑Arthur Monerie1 · Jon Robson1 · Buwen Dong1 · Dan Hodson1 Received: 21 April 2020 / Accepted: 2 October 2020 © The Author(s) 2020
Abstract We assess the effects of the North Atlantic Ocean Sea Surface Temperature (NASST) on North East Asian (NEA) surface temperature. We use a set of sensitivity experiments, performed with MetUM-GOML2, an atmospheric general circulation model coupled to a multi-level ocean mixed layer model, to mimic warming and cooling over the North Atlantic Ocean. Results show that a warming of the NASST is associated with a significant warming over NEA. Two mechanisms are pointed out to explain the NASST—North East Asia surface temperature relationship. First, the warming of the NASST is associated with a modulation of the northern hemisphere circulation, due to the propagation of a Rossby wave (i.e. the circumglobal teleconnection). The change in the atmosphere circulation is associated with advections of heat from the Pacific Ocean to NEA and with an increase in net surface shortwave radiation over NEA, both acting to increase NEA surface temperature. Second, the warming of the NASST is associated with a cooling (warming) over the eastern (western) Pacific Ocean, which modulates the circulation over the western Pacific Ocean and NEA. Additional simulations, in which Pacific Ocean sea surface temperatures are kept constant, show that the modulation of the circumglobal teleconnection is key to explaining impacts of the NASST on NEA surface temperature. Keywords AMV · North Atlantic · North East Asia · Climate variability · Circumglobal teleconnection pattern
1 Introduction In the mid-1990s, North East Asia (NEA) warmed substantially, with an increase in summer temperature reaching up to 1 °C (Chen and Lu 2014; Dong et al. 2016). These changes were associated with an increase in the summer maximum and minimum daily temperature, and with more numerous warmest days and tropical nights (Dong et al. 2016). In addition to the increase in surface temperature, precipitation decreased (Zhu et al. 2011; Qi and Wang 2012; Chen and Lu 2014). The mid-1990s warming had thus strong societal impacts over East Asia.
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00382-020-05477-y) contains supplementary material, which is available to authorized users. * Paul‑Arthur Monerie [email protected] 1
Department of Meteorology, National Centre for Atmospheric Science, University of Reading, Reading, UK
Previous studies have shown that the NEA warming was associated with a change in atmospheric circulation. In particular, the warming was associated with an anomalously high upper-level geopotential height and a change in lowlevel wind strength and direction (Zhu et al. 2011, 2012; Chen and Lu 2014). Several authors have proposed that the aforementioned anomalies in circulation are due to a perturbation of the circumglobal teleconnection pattern (CGT; Ding and Wang 2005), which
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