Calibrating the US National Fire Danger Rating System for Sardinia ^†

Abstract

Over the last two decades, extreme wildfires across Sardinia have challenged firefighting efforts and heavily impacted communities. Heatwaves may become more frequent, increasing wildfire occurrence and intensity across Mediterranean Europe. As conditions changes, fire managers need the best tools available to evaluate changes in local weather conditions and to assess their subsequent impact on fire potential in order to effectively prepare for and respond to wildfires, especially in fire-prone vegetation types like the Mediterranean maquis. Fire danger rating systems can fill this crucial need if properly calibrated. Here we explore the calibration of the fuel moisture models of the US National Fire Danger Rating System in the Mediterranean maquis of Northwest Sardinia. We leverage field measured near-surface weather, 10-h dead fuel moisture observations and live fuel moisture measurements to calibrate the dead and live fuel moisture models of the US National Fire Danger Rating System. We used grid search optimization to calibrate model parameters which improved relationships between measured and modeled fuel moistures. We then use calibrated fuel moistures to assess seasonal variations in the Energy Release Component and Burning Index from the US National Fire Danger Rating System and we evaluate model performance during extreme wildfire events across Sardinia. Ultimately, this calibrated model can contribute to the development and implementation of robust fire danger rating system to support fire management across Sardinia.