## Results
### Autumn Eastern Siberian Sea Ice Affecting the Winter BKS Precipitation
Figure 2: Correlations between autumn arctic sea ice extent and winter Barents–Kara Seas (BKS) precipitation with two data sets: (**a**) Hadley sea ice concentration data set; (**b**) National Centers for Environmental Prediction/Department of Energy (NCEP/DOE) sea ice concentration data set. Note the negative correlation indicated by blue in the circled EES (eastern Siberian Sea) region and white in the circled BKS region. All the data have been de-trended. Winter Atmospheric Circulation Anomalies Associated with Autumnal Eastern Siberian Sea Ice Extent Anomalies  
In the previous sections, we detailed the relationship between the autumnal eastern Siberian Sea ice anomalies and the BKS winter precipitation anomalies. To explore their relationship, we used mean composite and correlation analyses to investigate the correlation between the autumn eastern Siberian Sea ice extent and the winter atmospheric circulation activity in the northern hemisphere. Figure 4a shows the correlation coefficient between the autumn eastern Siberian Sea ice extent and the winter SLP (sea-level pressure) in the northern hemisphere. The colored regions passed the t test at 90% confidence. The autumn eastern Siberian Sea ice extent was negatively correlated with the winter SLP, indicating that when the Siberian Sea ice extent was reduced, a clear positive SLP anomaly existed in the Norwegian-Barents Sea that extended to Siberia through Eastern Europe. Figure 4b shows the correlation coefficient between the autumn sea ice index and the 500 hpa winter geopotential height. As seen in Figure 4b, compared with Figure 4a, the geopotential anomaly was highly concentrated in the Norway-Barents region. At the same time, the geopotential height anomalies in the Beaufort Sea, with the reverse phase of Norway-Barents, were found. The winter Norway-Barents-centered SLP (500 hpa geopotential height) anomaly (black part, 0\({}^{\circ}\) E-60\({}^{\circ}\) E, 60\({}^{\circ}\) N-75\({}^{\circ}\) N) was calculated. Figure 3: The correlation coefficient distribution between the winter precipitation of the Barents–Kara Sea and the autumn sea ice in August (**a**), September (**b**), October (**c**), and November (**d**). All the data have been de-trended. To explore the relationship between the autumn eastern Siberian Sea ice extent and the winter atmospheric circulation in the northern hemisphere, we also calculated the correlation coefficient between the two in winter. As shown in Table 1, the correlation coefficient between the Sep-Oct eastern Siberian Sea ice and the winter Siberian High (SH) was \(-0.5\), and the absolute value was much higher than the correlation coefficient between the Sep-Oct eastern Siberian Sea ice and the winter AO (arctic oscillation) (R = 0.30). Table 1 demonstrates that the relationship between the eastern Siberian Sea ice extent and the winter NAO index in Sep-Oct was very weak (R = 0.07). The correlation between the winter AO and winter SH was also very weak (R = \(-0.19\)). In addition, we calculated the relationship between SH and NAO (North Atlantic oscillation) with a correlation coefficient of 0.14. Table 2 shows the correlation coefficient between the BKS winter precipitation anomalies (20\({}^{\circ}\) E-60\({}^{\circ}\) E, 72\({}^{\circ}\) N-84\({}^{\circ}\) N) and the main atmospheric patterns of the northern hemisphere in winter. As shown in Table 2, a strong positive correlation existed between winter SH and BKS winter precipitation, but the positive correlation between BKS winter precipitation and AO/NAO was very weak, suggesting that winter SH played a greater role than AO/NAO in BKS winter precipitation: SH was closely negatively related to autumn eastern Siberian Sea ice extent and positively related to the BKS winter precipitation anomaly. These relationships will be explained in detail in the discussion section.