Spatial patterns of the daily non-convective rainfall in Castilla y Leon (Spain)

This work presents a regionalization of Castilla y Leon, an area located in the northwest portion of Spain, using 5-day rainfall. Daily data were avai lable for 119 sites for the 6-year period 1990-1995, between the months of September and May. The region presents a special orography which affects th e final results. Following similar studies (Van Regenmortel, 1995, Internat ional Journal of Meteorology 15, 313-323), Principal Component Analysis (PC A) (VARIMAX rotation) has been used together with the Cluster Analysis (War d and average-linkage) as methods of regionalization. The causes of rainfal l in Castilla y Leon, synoptic systems that affect the region, are obtained by using the PCA. As a result of a considerable reduction in the number of data, the properties of the different homogeneous rainfall areas are easie r to define. This reduction permits a simulation of rainfall with a small n umber of variables having only a slight loss of information (80.5% of the v ariance is explained). Copyright (C) 2000 Royal Meteorological Society.