Abstract
The variation of autumn Arctic sea ice is a critical indicator of temperature anomalies over the Eurasian continent during winter. The retreat of autumn Arctic sea ice is typically accompanied by negative anomalous winter temperatures over the Eurasian and North American continents. However, such sea ice temperature linkages notably change from month to month. The variation of the autumn Arctic sea ice area and the relationship between the month-to-month sea ice and winter temperature anomalies in China are investigated using the Hadley Centre’s sea ice dataset (HadiSST) and the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis dataset (ERA-Interim) during 1979–2018. We present the following results: The sea ice in the Barents and Kara seas (BK) during the autumn and winter seasons shows notable low-frequency variability. The retreat of sea ice in the BK from September to November is significantly associated with negative temperature anomalies in the following winter in China. However, the linkage between the sea ice in the BK in September and the winter temperatures is stronger than that in both October and November. An anomalous positive surface pressure is exhibited over the northwestern part of Eurasia in the winter that is linked to decreasing sea ice in the BK in the preceding September. This surface pressure favors the persistence and intensification of synoptic perturbations, such as blocking highs and surface cold highs, as well as the intensification of the Siberian High and the East Asian winter monsoon. These favorable conditions ultimately contribute to the formation of large-scale winter cold anomalies in China. Compared to low sea ice cover in October and November, a more oceanic heat storage in the upper BK induced by low sea ice cover in the BK leads to a larger heat release to tropospheric atmosphere in winter by surface heat flux and upward longwave radiation in the BK. This regional tropospheric warming results in a higher barotropic positive height anomaly over the Ural Mountains, and then more active cold advection from the high latitude affects East Asia.
Highlights
Arctic sea ice is a prominent indicator of global climate change
To explain how the preceding sea ice variation induces winter surface air temperature (SAT) anomalies in China, composite differences between the sea-level pressure (SLP) and the 850 hPa flow based on low-high OBKI (DBKI) values in September are presented in Figures 5(a) and 5(c). e difference field shows a positive anomalous winter pressure system in the northwestern part of the Eurasian continent that is suggestive of the northwestward expansion and intensification of the Cold Siberian High following the preceding loss of sea ice in the Barents and Kara seas (BK)
Conclusions e variation of the autumn Arctic sea ice area and the relationship between the month-to-month sea ice and the winter temperature anomalies in China are investigated in this study
Summary
Arctic sea ice is a prominent indicator of global climate change. A substantial loss of ice and a higher warming rate have been observed in the Arctic during recent decades, a phenomenon known as Arctic amplification, with a continuous increase in the global air temperature [1]. Severe cold events and anomalously heavy snowfalls have frequently affected most midlatitude regions of the Northern Hemisphere (NH), including major industrialized centers [2, 3] Along with this unforeseen cooling trend in the midlatitude regions of the NH, both the Cold Siberian High and the East Asian winter monsoon exhibit a substantial decadal intensification, leading to more active cold air outbreaks in China [4, 5]. Recent studies documented that there may be some physical linkages between the recent reduction of ice in the Arctic Ocean and cooling in the midlatitude continents of the NH through the anomalous atmospheric circulation response of sea ice loss [6]. Many previous studies have focused on the relationship between the variations in Arctic sea ice and atmospheric circulation patterns and the associated anomalous climate in China. Erefore, we will study the association of month-tomonth variability of the regional Arctic sea ice cover in the preceding autumn with the SAT anomalies and its possible linking pathway
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