Seasonally varying modes in long‐term variability of European precipitation during the 20th century

A gridded monthly terrestrial gauge‐based precipitation for 1901–2000 from the Climatic Research Unit, University of East Anglia, set is used to investigate leading seasonal modes in the long‐term precipitation variability over Europe and their links to atmospheric circulation. Performed empirical orthogonal function (EOF) analysis has shown that the leading modes of precipitation variability over Europe are clearly season‐dependent. The character of the links between regional precipitation and atmospheric circulation also features essential seasonality. The first EOF modes of the winter, spring, and summer seasonal mean precipitation over Europe are associated with the North Atlantic Oscillation (NAO). However, because the summer NAO differs significantly from the winter and spring NAO, the first EOF mode of the summer precipitation has a spatial‐temporal structure which is principally different from those of the winter and spring seasons. The first EOF mode of the fall precipitation is not associated with the NAO. This mode demonstrates a strong link to the Scandinavian teleconnection pattern. The second EOF modes of the winter and fall precipitation are linked to the east Atlantic and the NAO teleconnection patterns, respectively. Analysis of running correlations between the principal components of the leading EOF modes of precipitation and the NAO index has revealed nonstationarity of the links between European precipitation and the NAO. Moreover, there is evident seasonality in the character of the long‐term changes of the above links.