Temperature and Precipitation Variability and Trends in Northern Spain in the Context of the Iberian Peninsula Climate

Abstract

The longest precipitation and temperature series of the peninsular Spain and Balearic Islands are analysed covering the periods 1880-1995 and 1900-1997 respectively. To identify coherent behaviour in these series, the PCA method has been used, resulting in several major noise-filtered time series. For temperature data, although two statistically significant EOFs have been obtained for the western and eastern parts of Spain, the entire region can be described by one EOF and its time evolution by the first PC series. These time series show a general upward trend and some abrupt changes. On the other hand, for precipitation, we have obtained three significant EOFs, except for winter, when we find four EOFs. The first EOF can be associated with Andalusia and Spanish Interior, the second and third EOFs with Mediterranean and Cantabric coasts, alternatively, depending on the season. The analysis of the principal components series using moving average and the Mann-Kendall test, show significant long term decreases in precipitation for Mediterranean region and Interior (at least in some seasons) and an increase of the precipitation for the Northern coastal region. The changes found have been related to changes in the circulation patterns and discussed from the perspective of climatic change.