NAO and solar radiation variability in the European North Atlantic region

We explore the relationship between the NAO and the solar radiation spatio‐temporal variability in the European North Atlantic area during winter. Measured monthly sums of sunshine duration and short‐wave downward solar flux reanalysis data have been used. Correlation analysis between the NAO index and the measured sunshine duration shows a dipolar pattern, with maximum positive values (+0.75) over the Iberian Peninsula, and maximum negative values (−0.71) over Norway. Reanalysis results confirm these findings. Composite analysis shows, for northern Europe, negative anomalies (−10% to −20%) associated with NAO > 1 and positive anomalies (10% to 20%) associated with NAO < −1; while for southern Europe anomalies are, respectively, 10% to 20% and −10% to −20%. A stronger influence is found during the NAO negative phase; particularly, the northern British Isles, Norway and the Iberian Peninsula present a significant non‐linear response, with higher anomalies (10% to 20%) during this negative phase.