Getting to know the winter North Atlantic Oscillation

Abstract

The North Atlantic Oscillation (NAO) is a key atmospheric phenomenon that shapes winter climate patterns in the Northern Hemisphere, affecting sea level pressure, temperature, and precipitation. This study explores the NAO using ERA5 reanalysis data, and coupled atmosphereocean and atmosphere-only simulations to analyse its dynamics and impacts. Empirical Orthogonal Function analysis identifies the NAO as the dominant mode of variability, explaining up to 50% of sea level pressure variations in the North Atlantic-European region during boreal winter. Results illustrate that the NAO is primarily an atmospheric phenomenon, independent of oceanic coupling, as evidenced by consistent patterns across datasets. The study highlights the crucial role of the NAO in modulating regional precipitation and temperature patterns, with significant implications for climate research and socio-economic sectors