Publications

Modes of low-frequency variability have a major influence on the variability of the climate system at different temporal and spatial scales. Although the North Atlantic Oscillation explains a substantial portion of the climate variability in Europe, it is also necessary to consider other modes of low-frequency variability, such as the Scandinavian index, the eastern Atlantic or the eastern Atlantic/western Russia indices. Furthermore, the relationship between the modes of low-frequency variability and the climate in Europe cannot be considered to be stable over time. The aim of this paper is to assess the compatibility between the modes of low-frequency variability in Europe (computed using a principal component analysis (PCA)) and local circulation regimes (using an automated version of the Lamb weather-type classification), thus to observe how shifts in the positions of the modes of low-frequency variability in Europe, could affect local circulation. Our study area (NW Iberian Peninsula) was chosen because it is characterized by the passage of cold fronts associated with the storm track in the North Atlantic Ocean and is sensitive to any variability in precipitation and temperature that is linked to the main North Atlantic modes of low-frequency variability. The results show that there is a high degree of correlation between regional modes of low-frequency variability derived from a statistical approach (using PCA) and real physical circulations (as represented by circulation types). Furthermore, changes in the position of modes of low-frequency variability tend to favor some circulation types over others.