## Results
### Autumn Eastern Siberian Sea Ice Affecting the Winter BKS Precipitation
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Sep** & **Oct** & **Sep–Oct** \\ \hline DJF SH & \(-0.50\) *** & \(-0.50\) *** & \(-0.50\) *** \\ DJF AO & 0.24 & 0.31 * & 0.30 * \\ DJF NAO & 0.04 & 0.11 & 0.07 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Correlations between the autumn sea ice index and the winter arctic atmospheric circulation. Correlation coefficients over 90%, 95%, and 99% confidence levels are represented by *, ** and ***, respectively. DJF is December–January–February, SH is Siberian high, AO is arctic oscillation, NAO is North Atlantic oscillation. Figure 4: (**a**) Correlation coefficient distribution between sea ice index and sea-level pressure (SLP); (**b**) 500-hpa geopotential height. The colored regions passed the t test with a confidence level of 90%. All the data have been de-trended. Using the northern hemisphere meridional wind data, we calculated the correlation coefficient between the previous autumn eastern Siberian Sea ice extent and winter 850 hpa meridional wind in the northern hemisphere (Figure 5a). The correlation coefficient between winter SLP (500 hpa geopotential height) anomaly centered in the Norway-Barents Sea and the meridional wind at 850 hpa (500 hpa) in winter was also calculated (Figure 5b,c). The colored regions passed the t test at 90% confidence. When eastern Siberian Sea ice extent decreased in autumn, a significant positive winter SLP (500 hpa geopotential height) anomaly occurred in the Norwegian-Barents Sea. As a result, south (north) wind anomalies occurred in the Atlantic Ocean (Barents and Kara Sea). As can be seen from Figure 5b,c, a south wind anomaly was present in the Atlantic Ocean, which was conducive to the spread of moisture from the mid-low latitudes of the Atlantic to the Arctic. At the same time, north winds were blowing in the BKS. The north wind anomalies could spread the moisture from the Atlantic Ocean to said seas, resulting in increased precipitation in BKS. Figure 5a also shows similar results. In the 30 years of our available data, it can be observed that the entire arctic sea ice extent has been experiencing a rapid decline in September-October [32]. When the ice melting season was over, the Arctic was more open water than in the previous freeze period; as open water absorbed heat, the sea ice extent decreased compared to that in the previous freeze period [33; 34]. Changes in atmospheric circulation can lead to stronger precipitation anomalies or changes in factors associated with such anomalies [23]. To study the relationship between autumn eastern Siberian Sea ice extent and the winter BKS precipitation in depth, we used the 850 hpa water vapor transport anomaly in the high and low sea ice index years. Figure 6a shows the winter water vapor transport anomaly in the northern hemisphere during the low sea ice index years. As can be seen, a strong transport of water vapor was traveling from the lower latitudes of the Atlantic to the north across the Greenland Sea to the Arctic, before going south to the BKS. Thus, local convection and thermal anomalies were enhanced. This result was similar to that shown in Figure 5. However, the water vapor transport flux in other parts of the Arctic was weak \begin{table}
\begin{tabular}{c c c c} \hline  & **NAO** & **AO** & **SH** \\ \hline R & 0.08 & \(-\)0.04 & 0.58 *** \\ \hline \end{tabular}
\end{table} 
Table 2: Correlation between the winter Barents–Kara sea precipitation anomalies and winter arctic atmospheric circulation. Correlation coefficients over 90%, 95%, and 99% confidence levels are represented by *, ** and ***, respectively. Figure 5: **(a) Correlation coefficient distribution between the winter meridional winds in the northern hemisphere at 850 pha and autumn eastern Siberian Sea ice extent; (b) the Norway–Barents-centered SLP in winter; (c) correlation coefficient distribution between the winter meridional winds in the northern hemisphere at 500 pha and the Norway–Barents-centered 500 hpa geopotential height in winter.