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 Aragón (NE Spain). A high temperature day was established when air temperature was higher than 20 °C at 850 hPa. Temperature at 850 hPa was chosen because it properly characterizes the low troposphere state, and some of the problems that affect 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 behavior. The effects of those high temperatures days in large wildland fire patterns have been increasingly important in the last years of the series

Wildland fire typologies and extreme temperatures in NE Spain

“…Most of convective fires occurred under HTDs (more than 80% in terms of fire number and burned area). Additionally, the annual number of HTDs increased significantly in the study period in Aragón (Cardil et al 2013). This conspicuous increase could be part of the process detailed by Giannakopoulos et al (2009), who determined that in areas like Spain an increase in the occurrence of hot days and heat weaves is expected for the next decades.…”

“…Although the method did not find any significant shift at a point of the study period, we split the study period in two time intervals (1978-1993 and 1994-2012) addressing differences in HTD patterns to explore changes in terms of fire number, burned area and fire typologies. The second time interval includes the years with the highest values of number of HTDs (1994, 2003, 2012-Cardil et al 2013), large fires with extreme fire behavior occurred in Aragón and other regions as Catalonia or Valencia Community in these years and the annual number of HTDs was significantly higher than in the first period. Additionally, the periods were different due to socioeconomic, land abandonment and fire suppression changes.…”

“…This conspicuous increase could be part of the process detailed by Giannakopoulos et al (2009), who determined that in areas like Spain an increase in the occurrence of hot days and heat weaves is expected for the next decades. Paying attention to that change will be especially important, since more frequent HTDs will lead to a significant decrease in air humidity and fuel moisture (Cardil et al 2013), and then to the potential for extreme fire behavior (Cardil et al 2014a) and convective fire occurrence. The agricultural abandonment is the other factor to be considered.…”

Defining Extreme Wildfire Events: Difficulties, Challenges, and Impacts

“…Some authors prefer to use relative burnt area (BA) thresholds [25][26][27][28] but most of the definitions are based on absolute quantitative thresholds which can change in the course of time, as well as with the geographic area of reference [28,29]. In Europe, thresholds for LFs that have been proposed range from ≥ 100 ha (e.g., [30][31][32][33][34][35][36][37]) to ≥ 1000 ha [38]. In other regions in the world, the threshold ranges from the minimum values of ≥ 20 ha in Arizona (U.S.) [39], to 1000 ha in Australia [40], to 4950 ha in Boreal Shield ecozone of Ontario [41] and to 40,000 ha in the Western United States [42].…”

Calibration of FARSITE simulator in northern Iranian forests

“…The wildfire spread depends on complex interactions among terrain, fuel types, weather conditions, fire suppression and the heat released by the fire environment (Viegas et al, 1998;Forthofer and Butler, 2007;Fernandes, 2009;Lee et al, 2010;Sharples et al, 2012;Cardil et al, 2013). The use of fire spread models can help in the understanding of potential fire behavior, improve logistics and decision-making and thereby improve awareness and safety of firefighters.…”