Nonstationary influence of the North Atlantic Oscillation on European precipitation

This paper analyzes the changing role of the North Atlantic Oscillation (NAO) in European precipitation in relation to interdecadal shifts in the atmospheric dynamic over the North Atlantic region. For this purpose, moving window correlations between precipitation and NAO have been related to the interdecadal variability of atmospheric pressure patterns. Analyses have been replicated using observed climate data for the twentieth century, paleoclimate reconstructions since 1785, and physically modeled climate by AOGCMs (CGCM3.1(T63), 20C3M). Results evidence that nonstationary relationship of the NAO pressure centers, which have been occurred at least since the last 2 centuries. Such displacement of the pressure NAO centers point to possible existence of different NAO patterns, which may help to explain why studies relating NAO to European climate behavior have not shown systematically strong correlations in the course of the twentieth century. A general trend toward a strengthening of the NAO-precipitation relationship over most of Europe has been detected for the twentieth century.