Principal component analysis of mediterranean rainfall

Abstract Principal component analysis has been used to group the European Mediterranean stations into homogeneous regions. The annual rainfall records used were from 90 stations distributed all over the European Mediterranean countries. Major components were selected by a dominant‐variance selection rule, called rule N. The most important component corresponds to a fairly uniform field, the second marks the climatological distribution of cyclonic disturbances, the third shows a gradient from north‐east to south‐west and the fourth exhibits the existence of two centres of anomalies with a negative ridge and a positive value on each side. A cluster analysis based on these major eigenvectors shows the existence of five climatic regions. A subjective method, using the zero‐line characterizing the significant eigenvectors, shows similar results.