Trends in adverse weather patterns and large wildland fires in Aragón (NE Spain) from 1978 to 2010

Abstract

This work analyzes the effects of high temperature days on large wildland fires during 1978–2010 in Arag ́ on (NE Spain). A high temperature day was established when air temperature was higher than 20 ◦ C at 850 hPa. Tempera- ture at 850 hPa was chosen because it properly characterizes the low troposphere state, and some of the problems that af- fect surface reanalysis do not occur. High temperature days were analyzed from April to October in the study period, and the number of these extreme days increased significantly. This temporal trend implied more frequent adverse weather conditions in later years that could facilitate extreme fire be- havior. The effects of those high temperatures days in large wildland fire patterns have been increasingly important in the last years of the series.

We are thankful to the University of Lleida and Pau Costa Foundation for supporting this study through a partial grant to fund Cardil’s PhD studies. We also thank Joaquim García-Codina, Miguel Lazaro and Luis Besold for help in the classification of HTDs and other detailed checking in the official wildland fire data base, and finally to Marta Fajo-Pascual and Antonio Muñoz for help in the statistical analysis and the EGIF Database