NAO and solar radiation variability in the European North Atlantic region

[1] 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.