MOTEDAS: a new monthly temperature database for mainland Spain and the trend in temperature (1951-2010)

We have developed a new monthly temperature database for mainland Spain by using the complete holding of maximum and minimum monthly mean values stored at the Spanish National Meteorological Agency (AEMet). After an exhaustive quality control exercise, the data set includes 1358 complete series, and a high-resolution grid (0.1 degrees x0.1 degrees) was calculated to analyse monthly trends. There has been an uneven increase in the mean values of maximum and minimum temperatures in the Spanish mainland from 1951 to 2010. The maximum monthly mean temperature values have risen mostly in late winter/early spring and the summer, while the minimum monthly mean temperature values have increased in summer, spring and autumn in southern areas. The spatial pattern of the diurnal temperature range shows a clear north-south gradient in summer, with positive trends in the north and negative trends in the south; furthermore, a negative pattern has been detected in the south in spring and autumn. These areas, particularly the Mediterranean coastland, have been subject to dramatic urbanization and land use changes during the past 30 years that may have affected nocturnal temperatures, in particular. Thus, warming processes in the Iberian Peninsula appear to be influenced both by global factors and more local ones, and their effects should be differentiated spatially.