Fig. 4.

The relationship of environmental properties to the preceding October zonal winds. a Regression of 1979–2015 surface net shortwave radiation averaged from December to February (black contours) and the timing of ice advance (colored shading) on the normalized and detrended prior October zonal wind index. The net shortwave regression is contoured at 1 W m⁻², negative values are dashed, and the zero line omitted. Regression of ice advance is only shown where significant at the 95% level. b Regression of monthly 1979–2015 net shortwave (solid; left axis) and 1982–2015 SST (dash; right axis) averaged in the region denoted by the box on a on the normalized and detrended October zonal wind index. Significant values are denoted by the circles