The Galician-Portuguese biogeographic sector. An initial advance

This work calculates and analyses monthly, seasonal and annual precipitation trends over continental Spain between 1961 and 2010, according to data from 144 weather stations widely distributed throughout the study area. The magnitude and sign of the trends were evaluated with Sen¿s slope estimator and their statistical significances were determined with the nonparametric MannKendall test. In general terms, the rainfall trends for the period and the study area are mainly non nonsignificant at the monthly, seasonal and annual timescales. By and large, we noted the highest number of weather stations with positive significant trends in September and October, whereas the highest number of stations with negative significant trends was observed in February, June, winter, summer and at the annual time¬scale. The most pronounced decreases occurred in June (¿18.58 mm/50years) and in summer (27.67 mm/50years) in the south, which points to an intensification of mediterraneity in this area. We observed a sign asymmetry in significant rainfall trends during winter, spring and at the annual timescales between the north (negative) and the southeast (positive).