Assessing fire intensity and burned area in Portugal: the influence of meteorological variables using copula functions

Fire activity is intrinsically linked to severe meteorological conditions, which explain most of the interannual variability of burned area (BA). Nonetheless, the effect of weather conditions on fire intensity is less understood. Using copula functions, the relationship between fire intensity and burned area with meteorological conditions in northern and central Portugal was studied. The occurrence of high weekly Fire Radiative Power (FRP) and BA under extreme wind speed and temperature was assessed at four time periods from March to October. Results indicate that wind speed was the main driver of both FRP and BA, with the probability of high fire activity exceeding 80%. The influence of northwesterly (NW) winds intensified across the fire season, whereas southeasterly (SE) winds exhibited the inverse pattern. However, divergent patterns emerged early in the season: Northern and westerly (NW) wind patterns yielded a significantly higher probability of elevated BA relative to FRP, while southerly and easterly (SE) winds conversely suppressed BA potential. In comparison, temperature exerted a lower relative influence, with peak probabilities of high fire activity reaching 70% for FRP and 60% for BA. Like before, opposite results were obtained at the beginning of the season, which were much higher for BA. This study contributes to a better understanding of the role of extreme fire weather along the fire season, thus contributing to improving fire management strategies.