Regional rainfall response to the North Atlantic Oscillation (NAO) across Great Britain

The NAO has been long studied as the primary teleconnection affecting British and European climate. However, previous studies have focused on extremes or have been spatially and temporally limited. In recent years our ability to predict the NAO has improved. Also new research is emerging suggesting that the NAO is a key driver of hydrological extremes. These factors mean there is renewed value in enhancing our understanding of how the NAO influences general rainfall patterns. In this study we spatially analyse correlations between NAO indices and monthly rainfall data and the Standardised Precipitation Index. We also map mean monthly rainfall differences under NAO positive and negative conditions. Based on our results we identify three main observations: (I) there is sensitivity in the rainfall patterns to the chosen NAO index; (II) there is a clear winter north/west and south/east divide in rainfall patterns; (III) the NAO does have an effect on summer rainfall patterns, although the spatiality of these patterns is less distinctive than in winter. As far as we are aware this is the first national scale, monthly NAO-rainfall analysis undertaken for a long period.