Abstract
During the past few decades, Arctic sea-ice has declined rapidly in both autumn and winter, which is likely to link extreme weather and climate events across the Northern Hemisphere midlatitudes. Here, we use reanalysis data to investigate the possible linkage between mid–high-latitude atmospheric circulation and Arctic sea-ice loss in different geographical locations and seasons and associated impacts on wintertime climate on interdecadal timescales. Four critical sea-ice subregions are analyzed in this study—namely, the Pan-Arctic, Barents–Kara–Laptev Seas (BKL), East Siberia–Chukchi–Beaufort Seas (EsCB), and Bering Sea (Ber). Results suggest that interdecadal reduction of autumn sea-ice, irrespective of geographical location, is dynamically associated with the negative phase of the North Atlantic Oscillation (NAO) in the subsequent winter via stratospheric pathways. Specifically, autumn sea-ice loss appears to cause a weakened stratospheric polar vortex that propagates to the troposphere in the ensuing months, leading to lower surface air temperature and a deficit in precipitation over Siberia and northeastern North America. Meanwhile, an anomalous cyclone over Europe favors excessive precipitation over southern Europe. For wintertime sea-ice loss in the Pan-Arctic and BKL, a weak positive NAO phase, with a dipole pressure pattern over Greenland–northeastern North America and North Atlantic, and a shrunken Siberian high over Eurasia are observed over mid–high-latitudes. The former results in excessive precipitation over northwestern and southeastern North America, whilst the latter leads to less precipitation and mild winter over Siberia. In contrast, Ber sea-ice loss is associated with a circumglobal wave train downstream of the Bering Sea, leading to extensive warming over Eurasia. The anomalous dipole cyclone and anticyclone over the Bering Sea transport more Pacific and Arctic water vapor to North America, and the anomalous cyclone over the Barents Sea results in abundant precipitation in Siberia. Such midlatitude anomaly is dynamically linked to winter sea-ice loss, mainly through tropospheric rather than stratospheric pathways. These results have important implications for future seasonal and interdecadal forecasts in the context of ongoing sea-ice decline.
Highlights
In recent decades, the midlatitudes of the Northern Hemisphere have experienced more frequent cold winters and extreme weather events (Wu et al, 2011; Cohen et al, 2014; Li et al, 2015; Cohen et al, 2020; Wang et al, 2021)
This study aims to address two questions: 1) How does Arctic sea-ice loss in different seasons and at different locations contribute to the wintertime atmospheric circulation anomalies and associated impact on temperature and precipitation? 2) What is the Arctic-midlatitude linkage on interdecadal timescales? this paper investigates the interdecadal linkage between Northern Hemisphere temperature and precipitation and sea-ice change in diverse regions and seasons
There is emerging evidence that the geographical location of sea-ice loss is critically important in determining the large-scale atmospheric circulation anomalies and associated impacts on the midlatitudes (Screen, 2017A)
Summary
The midlatitudes of the Northern Hemisphere have experienced more frequent cold winters and extreme weather events (Wu et al, 2011; Cohen et al, 2014; Li et al, 2015; Cohen et al, 2020; Wang et al, 2021). Wu et al (2017) investigated a cold event that occurred in East Asia during January–February 2012 and its possible association with Arctic sea-ice loss. They found that weakening of the Aleutian low and rapid strengthening of the Siberian high, concurrent with a polar blocking high aloft, were crucial precursors for cold-air outbreaks from the Arctic. Liu et al (2016) reported that the reduction of autumn sea-ice across the Arctic Ocean is accompanied by dry conditions over central China and wet conditions over South China and North China in early winter, via two wave-train structures
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