Abstract
Investigating the contrast between wintertime warming in the Arctic and cooling in Eurasia is of great importance for understanding regional climate change. In this study, we propose a dynamic and thermodynamic coupling view of the linkages between wintertime Arctic warming and Eurasian cooling since 1979. The key factors are the energy budget at the Earth’s surface, the diabatic heating and baroclinicity of the atmosphere, and subsurface ocean heat. A summertime origin of wintertime Arctic warming suggests a partial driving role of the Arctic in wintertime Eurasian cooling. The reasons for this finding are as follows. First, there is a dipole pattern in the diabatic heating change in winter over the Arctic Ocean corresponding to the anticyclonic circulation that links Eurasian cooling and Arctic warming. Second, the change in diabatic heating of the atmosphere is determined by sensible heat at the Earth’s surface through vertical diffusion. Third, the positive sensible heat change in the eastern Arctic sector in winter originates from the summertime enhanced absorption of solar radiation by the subsurface ocean over the sea ice loss region. Meanwhile, the negative sensible heat change in the western Arctic sector and wide Arctic warming can be explained by the circulation development triggered by the change in the east. Additionally, the background strong baroclinicity of the atmosphere in mid-high latitudes and corresponding two-way Arctic and mid-latitude interactions are necessary for circulation development in winter. Furthermore, the seasonality of the changes indicates that Eurasian cooling occurs only in winter because the diabatic heating change in the Arctic is strongest in winter. Overall, the comprehensive mechanisms from the summertime Earth’s surface and subsurface ocean to the wintertime atmosphere suggest a driving role of the Arctic. Note that the situation in interannual variability is more complex than the overall trend because the persistence of the influence of summertime sea ice is weakly established in terms of interannual variability.
Highlights
As one of the most remarkable features of global warming, amplified Arctic warming has received intensive attention and has been the subject of a wide range of studies (Shepherd 2016; Stouffer and Manabe 2017)
From a general dynamic and thermodynamic coupling view, this paper investigated the linkages between Arctic warming and Eurasian cooling in winter since 1979
This study intends to build a comprehensive picture of the mechanisms concerning the key processes, including the featured wintertime atmospheric circulation patterns, wintertime energy budget at the Earth’s surface and its summertime origins associated with the sea ice, the coupling between the energy budget at the Earth’s surface and the diabatic heating of the atmosphere aloft in winter, the detailed seasonality in the circulation patterns and diabatic heating of the atmosphere, the crucial role of the baroclinicity, the situation concerning the interannual and decadal variability, and the effect of the subsurface ocean heat transports
Summary
As one of the most remarkable features of global warming, amplified Arctic warming has received intensive attention and has been the subject of a wide range of studies (Shepherd 2016; Stouffer and Manabe 2017). Honda et al (2009) and Nakamura et al (2015) propose that amplified warming around the Barents-Kara Sea can stimulate an anomalous stationary wave train that induces an enhanced Siberian high, and eventually cold conditions in Eurasia. Li et al (2019) and Zhang et al (2020) suggest that warming over the Barents-Kara Seas can affect wintertime cooling over China through stationary waves, jet streams, Ural blocking, the Siberian High, and the East Asian winter monsoon. One key question is the divergence in the conclusions in previous studies regarding the role of Arctic amplification and sea ice in the observed Eurasian cooling (e.g., reviewed by Cohen et al (2020) and Blackport and Screen (2020b), and debates such as between Mori et al (2021) and Zappa et al (2021)).
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