Detection of statistically significant trends in the summer precipitation of mainland Spain

In the context of global warming, it is a well-known fact that there is an increase in precipitation in middle latitudes. Convective phenomena have also been on the increase in the past few decades. It is gradually becoming more difficult to characterize climatic trends in middle latitudes. Data show that there may be different results depending on the study zones. Thus, it is interesting to study climatic changes in recent precipitation series, especially if we can have at our disposal a dense network of rainfall stations with reliable precipitation series. The analysis of precipitation series in 333 rainfall stations from 1961 to 1990 has revealed that summer precipitation shows a statistically significant trend in wide areas of Mainland Spain. In the months of July and August, the precipitation is exclusively convective. In those months, the precipitation increased in 20% of the southern areas, that is, in those areas where temperatures are on average higher. June and September present different trends showing a decrease in precipitation in 10% of the territory. (C) 2004 Published by Elsevier B.V.