## Results
### Autumn Eastern Siberian Sea Ice Affecting the Winter BKS Precipitation  
Using the Hadley monthly sea ice concentration dataset, we estimated the autumn eastern Siberian Sea ice extent. To explore the relationship between said extent and the winter Barents-Kara Sea precipitation, the correlation coefficient between the two was calculated. Before the correlation analysis, all the data were de-trended. Figure 2a shows the correlation coefficient mentioned. The colored regions passed the t test at 90% confidence. A negative signal in the eastern Siberian Sea was clearly seen (near 130\({}^{\circ}\) E-180\({}^{\circ}\) E, 72\({}^{\circ}\) N-80\({}^{\circ}\) N). This indicated that the melting of the autumn eastern Siberian Sea ice was related to an increase in winter precipitation in BKS. The eastern Siberian Sea is one of the arctic marginal seas, in which the ice changes dramatically. In September, the eastern Siberian Sea ice was at its smallest extent. A decrease in autumn eastern Siberian Sea ice extent was observed to an increase in Siberian High (SH) SLP, which in turn caused the Eurasia and East Asian high latitudes to cool [30]. In addition to eastern Siberia, a weak negative signal was seen in Novaya Zemlya (near 60\({}^{\circ}\) E, 72\({}^{\circ}\) N), while a weak positive signal was found in the Parry Islands (near 120\({}^{\circ}\) E, 82\({}^{\circ}\) N). To verify the negative relationship between the autumn eastern Siberian Sea ice and the winter precipitation in the BKS, we calculated the correlation coefficient between the NCEP/NCAR autumn sea ice concentration and BKS winter precipitation (Figure 2b). There is a negative signal only in the eastern Siberian Sea, with those in other sea areas disappearing. Figure 1: Winter precipitation anomalies in the Barents and Kara Seas from 1988 to 2017, unit: mm. To study the effects of the autumn eastern Siberian Sea ice on winter precipitation of the BKS, we chose August, September, October, and November as the relevant months to calculate the relationship between the two. Through calculations, we found that the September eastern Siberian Sea ice concentration had the greatest impact on winter precipitation in said sea. Figure 3 shows the distribution of correlation coefficients between BKS winter precipitation and eastern Siberian Sea ice in August, September, October, and November. First, in August (Figure 3a), the negative correlation area appeared in the eastern Siberian Sea, but this only covered a small region, showing a discrete distribution. In September (Figure 3b), the negative correlation area still appeared in the eastern Siberian Sea, and the negative signal area extended to the north, with the coverage area reaching the maximum. In October (Figure 3c), the negative correlation zone in the eastern Siberian Sea began to dissipate, only covering the marginal eastern Siberia sea. In November (Figure 3d), the negative correlation zone of the eastern Siberian Sea was completely dissipated. The eastern Siberian Sea is an arctic marginal sea, and August and September are periods of dramatic changes in ice in this sea, with it retreating rapidly. In October, the sea ice of said sea was in the icing period and changed relatively little. In November, the eastern Siberian Sea ice froze and barely changed. We defined the autumn eastern Siberia sea ice extent anomalies (the black area in Figure 2, near 130\({}^{\circ}\) E-180\({}^{\circ}\) E, 72\({}^{\circ}\) N-80\({}^{\circ}\) N) in September-October (Sep-Oct) from 1988 to 2017 as the sea ice index. The standard deviation of the sea ice index was used as a threshold. When the index was higher (lower) than one standard deviation, we used it as a high- (low-)sea ice index year. Therefore, the high-sea ice index years were 1988, 1992, 1994, 1996, 1997, 1998, and 2001, while the low-sea ice index years were 2007, 2008, 2012, and 2016.