Wildland fire potential outlooks for Portugal using meteorological indices of fire danger

Abstract

Abstract. Portugal is recurrently affected by large wildfire events that have serious impacts at the socio-economic and environmental levels and dramatic consequences associated with the loss of lives and the destruction of the landscape. Accordingly, seasonal forecasts are required to assist fire managers, thus contributing to alter the historically-based purely reactive response. In this context, we present and discuss a statistical model to estimate the probability that the total burned area during summer will exceed a given threshold. The statistical model uses meteorological information that rates the accumulation of thermal and vegetation stress. Outlooks for the 39-year study period (1980–2018) show that, when the statistical model is applied from May 26 to June 30, out of the six severe years, only one year is not anticipated as potentially severe and, out of the six weak years, only one is not anticipated as potentially weak. The availability of outlooks of wildfire potential with an anticipation of up to one month before the starting of the fire season, such as the one proposed here, may serve to provide clear directions for the fire community when planning prevention and combating fire events.

Consideration of compound drivers and impacts in the disaster risk reduction cycle

“… 25 [4] Wildfires Multivariate Thermal and vegetation stress Improving wildfire forecasting driving anticipatory actions [S] Nunes et al. 26 [5] Wildfires Preconditioning Antecedent drought, rare meteorology and human drivers [N] Ramos 27 [6] Crop failures Multivariate Hot and wet conditions Improving forecasting of crop failures [S] Ben-Ari et al. 28 [7] Ecosystem carbon uptake Multivariate Hot and dry conditions Seasonal forecasting of summer extremes guided by interactions between carbon and water uptakes [S] Bastos et al.…”

“…Examples of analyses of historic events are the 1816 European year without a summer, driven by a combination of a major volcanic eruption and a regional atmospheric circulation 24 ; a large number of ice storms in China in 2008 25 ; extensive coastal-fluvial flooding in Ireland due to exceptionally wet autumn in 2009 23 ; an “Aqua Alta” compounding high water event in Venice 59 ; and precursors of fire weather conditions in Portugal since 1980. 26 For the wildfires in Portugal in October 2017—with nearly 200,000 ha of burnt area in just 24 h and 50 fatalities—several compounding features were playing a role. 27 These included a long-term preconditioning leading to cumulative hydric stress of vegetation, the passage of hurricane Ophelia off the Coast of Portugal advecting large masses of hot and dry air, and a negligent human driver of ignitions associated with agricultural practices.…”