title: Deciphering the impact of uncertainty on the accuracy of large wildfire spread simulations.
abstract: Predicting wildfire spread is a challenging task fraught with uncertainties. 'Perfect' predictions are unfeasible since uncertainties will always be present. Improving fire spread predictions is important to reduce its negative environmental impacts. Here, we propose to understand, characterize, and quantify the impact of uncertainty in the accuracy of fire spread predictions for very large wildfires. We frame this work from the perspective of the major problems commonly faced by fire model users, namely the necessity of accounting for uncertainty in input data to produce reliable and useful fire spread predictions. Uncertainty in input variables was propagated throughout the modeling framework and its impact was evaluated by estimating the spatial discrepancy between simulated and satellite-observed fire progression data, for eight very large wildfires in Portugal. Results showed that uncertainties in wind speed and direction, fuel model assignment and typology, location and timing of ignitions, had a major impact on prediction accuracy. We argue that uncertainties in these variables should be integrated in future fire spread simulation approaches, and provide the necessary data for any fire model user to do so.
authors.affiliation: Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, Lisboa, Portugal. Electronic address: aklibenali@gmail.com.
authors.forename: Akli
authors.initials: A
authors.lastname: Benali
authors.affiliation: LAETA, IDMEC, Instituto Superior Técnico, Universidade Lisboa, Departamento de Engenharia Mecânica, LASEF, Av. Rovisco Pais, 1, Lisboa, Portugal.
authors.forename: Ana R
authors.initials: AR
authors.lastname: Ervilha
authors.affiliation: Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, Lisboa, Portugal.
authors.forename: Ana C L
authors.initials: ACL
authors.lastname: Sá
authors.affiliation: Centro de Investigação e de Tecnologias Agro-Ambientais e Biológicas, Universidade de Trás-os-Montes e Alto Douro, Quinta de Prados, Vila Real, Portugal.
authors.forename: Paulo M
authors.initials: PM
authors.lastname: Fernandes
authors.affiliation: Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, Lisboa, Portugal.
authors.forename: Renata M S
authors.initials: RMS
authors.lastname: Pinto
authors.affiliation: Instituto Dom Luís, Faculdade de Ciências da Universidade de Lisboa, Campo Grande Edifício C8, Piso 3, Lisboa, Portugal.
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Trigo
authors.affiliation: Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, Lisboa, Portugal.
authors.forename: José M C
authors.initials: JMC
authors.lastname: Pereira
keywords: FARSITE; Fire behavior; Hotspots; MODIS; Satellite; Spatial discrepancy