| Summary: | Based on reanalysis datasets and sea-ice sensitivity experiments, this study has pointed out that the autumn sea ice loss in East Siberian-Chukchi-Beaufort (EsCB) Seas significantly increases the frequency of winter extreme low temperature over western-central China. Autumn sea ice loss warms the troposphere and generates anticyclonic anomaly over the Arctic region one month later. Under the effects of synoptic eddy-mean flow interaction and anomalous upward propagated planetary wave 2, the Arctic anticyclonic anomaly strengthens and develops toward Greenland-Northern Europe, accompanied by a weakened stratospheric polar vortex. In winter, following intra-seasonal downward propagation of stratospheric anomalies, the Northern European positive geopotential anomalies enhance and expand downstream within 7 days, favoring Arctic cold air east of Novaya Zemlya southward (hyperpolar path) accumulating in Siberia around Lake of Baikal. In the subsequent 2~3 days, these cold anomalies rapidly intrude western-central China and induce abrupt sharp cooling, thus more frequent extreme low temperature there.
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