title: Solar forcing synchronizes decadal North Atlantic climate variability.
abstract: Quasi-decadal variability in solar irradiance has been suggested to exert a substantial effect on Earth's regional climate. In the North Atlantic sector, the 11-year solar signal has been proposed to project onto a pattern resembling the North Atlantic Oscillation (NAO), with a lag of a few years due to ocean-atmosphere interactions. The solar/NAO relationship is, however, highly misrepresented in climate model simulations with realistic observed forcings. In addition, its detection is particularly complicated since NAO quasi-decadal fluctuations can be intrinsically generated by the coupled ocean-atmosphere system. Here we compare two multi-decadal ocean-atmosphere chemistry-climate simulations with and without solar forcing variability. While the experiment including solar variability simulates a 1-2-year lagged solar/NAO relationship, comparison of both experiments suggests that the 11-year solar cycle synchronizes quasi-decadal NAO variability intrinsic to the model. The synchronization is consistent with the downward propagation of the solar signal from the stratosphere to the surface.
authors.affiliation: Research Division Ocean Circulation and Climate, GEOMAR Helmholtz Centre for Ocean Research, Düsternbrooker Weg 20, 24105 Kiel, Germany.
authors.forename: Rémi
authors.initials: R
authors.lastname: Thiéblemont
authors.affiliation: Research Division Ocean Circulation and Climate, GEOMAR Helmholtz Centre for Ocean Research, Düsternbrooker Weg 20, 24105 Kiel, Germany.|Christian-Albrechts-Universität zu Kiel, Christian-Albrechts-Platz 4, 24118 Kiel, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Matthes
authors.affiliation: Bjerknes Centre and Geophysical Institute, University of Bergen, Postboks 7803, 5020 Bergen, Norway.
authors.forename: Nour-Eddine
authors.initials: NE
authors.lastname: Omrani
authors.affiliation: Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Kodera
authors.affiliation: Research Division Ocean Circulation and Climate, GEOMAR Helmholtz Centre for Ocean Research, Düsternbrooker Weg 20, 24105 Kiel, Germany.
authors.forename: Felicitas
authors.initials: F
authors.lastname: Hansen