Multiproxy reconstructions of the North Atlantic Oscillation

Multiproxy composite reconstructions of North Atlantic Oscillation (NAO) in dices are presented spanning the last three centuries. These composite time series draw on four nearly independent reconstructions derived from differ ent combinations of global and North Atlantic sector climate proxy data (e. g., tree rings and ice cores) as well as long instrumental records. A compo site reconstruction based on all four series (R4) extends from 1750 to 1979 , while another version based on only three series (R3) extends from 1701 t o 1979. Both composite reconstructions outperform the individual series bas ed on correlation and verification statistics. These results suggest that e ach individual series reflects different aspects of the NAG, such that when combined, they yield more robust reconstructions. As to be expected, these composite reconstructions, based on both proxy and long instrumental data, yield more optimal results than individual or composite reconstructions ba sed on proxy data alone. The reconstructions presented here provide an impr oved means of addressing features evident in the instrumental record with r espect to those of prior centuries. One such feature evident in the reconst ructions is an apparent increase in variance in the instrumental period rel ative to the past record.