Recent trends and climate change indices of precipitation and temperature in Andorra (1935-2000)

Abstract

This paper shows the results obtained for the calculation of annual and seasonal trends of maximum and minimum temperature and precipitation from three climatic series of the Principality of Andorra (Pyrenees), and located between 1140 and the 1645 m. The estimated trends have been obtained for the period 1935-2008 corresponding to the whole length of the series, and for the sub-period 1950-2008. From the same series, at a daily resolution, the indices of change defined by the ETCCDMI (Expert Team on Climate Change Detection Monitoring and Indices) have been also calculated. The results represent a solid description of the Andorran climate dynamics over the past eight decades and provide insight into the variability and climate change experienced in the Pyrenean country, characterized by its high altitude. The results confirm the trends identified regionally by other agencies, both French and Spanish. This confirms the significant increase in air temperature for the annual mean maximum temperature (0.13 to 0.15 ºC/decade), for the summer maximum temperature (0.22 ºC/decade), and the summer minimum temperature (0.11 ºC/ decade). These trends are reinforced when the analysis focuses on the sub-period 1950-2008. For precipitation and for the period 1935-2008, only significant decreasing trends are obtained in the station Central and in summer (-5.4%/decade), while this behaviour is generalized and strengthened if we stick to the period 1950-2008. Finally, the results for the calculation of the ETCCDMI daily indices confirm and detail the results obtained at coarser resolution. Thus, the indices computed from the temperature series show an increase in extreme warm days and a decrease of their opposites. For precipitation rates, significant trends were not found for the period 1935-2008, while several indices did show statistically significant decreasing values for the sub-period 1950-2008.