Sensitivity of the boreal winter atmosphere to sea ice anomalies in autumn and winter over Barents Sea

Based on the ERA-Interim reanalysis data, sensitivity of the boreal winter atmosphere to sea ice anomalies with different amplitudes in autumn and winter over the Barents Sea is explored by boundary forcing the Community Atmosphere Model 4.0 (CAM4). Both the winter mean atmospheric responses and the typical modals at the mid-high latitudes are studied. The results show that sea ice loss over the Barents Sea in winter can generate anomalous upward turbulent heat flux, which warms the local lower atmosphere and increases local atmospheric moisture with the magnitudes and extents consistent with sea ice anomalies. Specifically, the responses of atmospheric circulation and surface air temperature over the Eurasian continent are nonlinear and change with time. Although the reduction of the Barents Sea ice in autumn does not cause significant local temperature anomalies in winter, it leads to stronger and wider temperature and circulation anomalies over the Eurasian continent. The results indicate that autumn sea ice change can independently affect the mid-latitude atmosphere in winter. In addition, the intensity and location of the Siberian high and the North Atlantic Oscillation（NAO）phases in different months during winter have different responses to the reduction of the Barents Sea ice. In December and January, the Siberian high tends to become stronger and shifts more eastward in response to winter sea ice loss over the Barents Sea, and opposite is true in February. However, with the sea ice loss in autumn, the Siberian high is more likely to be stationary. And the negative phase of NAO (NAO⁻) occurs more frequently in late winter, but strong NAO⁻ occurs less frequently. The above results provide a reference for understanding the impact of the Barents Sea ice loss on weather and climate in the Northern Hemisphere.