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Influence of the Solar Cycle on the North Atlantic Oscillation
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  • Yuhji Kuroda,
  • Kunihiko Kodera,
  • Kohei Yoshida,
  • Seiji Yukimoto,
  • Lesley J. Gray
Yuhji Kuroda
Meteorological College, Japan Meteorological Agency

Corresponding Author:[email protected]

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Kunihiko Kodera
Nagoya University
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Kohei Yoshida
Meteorological Research Institute
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Seiji Yukimoto
Meteorological Research Institute
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Lesley J. Gray
University of Oxford
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Abstract

We examine the influence of the solar cycle on the North Atlantic Oscillation (NAO) on its pathway from the upper stratosphere to the surface by applying lagged regression analyses to recent observations, historical observations covering 194 years, and an Earth system model simulation covering 165 years. The propagation of the solar signal can well be explained by a top-down mechanism, but one that was strongly affected by ocean dynamics. The solar signal first appears in the subtropical upper stratosphere as a temperature signal. The associated zonal wind signal then propagates downward to the surface in response to stratospheric variability known as the Polar-night Jet Oscillation. The NAO signal tends to appear in February during years of peak solar activity. The solar signal is further modulated such that positive NAO signals tend to appear earlier in winter with increasing years after peak solar activity, which we think to be an oceanic effect. The fluctuations and amplitude modulation of the solar–NAO relationship on a 50-year time scale also suggest that there will be nonlinear interactions between solar forcing and ocean dynamics.
16 Jan 2022Published in Journal of Geophysical Research: Atmospheres volume 127 issue 1. 10.1029/2021JD035519