Data-driven surrogate model with latent data assimilation: Application to wildfire forecasting.

The large and catastrophic wildfires have been increasing across the globe in the recent decade, highlighting the importance of simulating and forecasting fire dynamics in near real-time. This is extremely challenging due to the complexities of physical models and geographical features. Running physics-based simulations for large wildfire events in near real-time are computationally expensive, if not infeasible. In this work, we develop and test a novel data-model integration scheme for fire progression forecasting, that combines Reduced-order modelling, recurrent neural networks (Long-Short-Term Memory), data assimilation, and error covariance tuning. The Reduced-order modelling and the machine learning surrogate model ensure the efficiency of the proposed approach while the data assimilation enables the system to adjust the simulation with observations. We applied this algorithm to simulate and forecast three recent large wildfire events in California from 2017 to 2020. The deep-learning-based surrogate model runs around 1000 times faster than the Cellular Automata simulation which is used to generate training data-sets. The daily fire perimeters derived from satellite observation are used as observation data in Latent Assimilation to adjust the fire forecasting in near real-time. An error covariance tuning algorithm is also performed in the reduced space to estimate prior simulation and observation errors. The evolution of the averaged relative root mean square error (R-RMSE) shows that data assimilation and covariance tuning reduce the RMSE by about 50% and considerably improves the forecasting accuracy. As a first attempt at a reduced order wildfire spread forecasting, our exploratory work showed the potential of data-driven machine learning models to speed up fire forecasting for various applications. • We are the first to train ML surrogate models for dynamical fire diffusion problems with a stochastic simulation code. • We combine ROM, RNN, DA and error covariance tuning for real-time wildfire nowcasting coupled with satellite observations. • The proposed surrogate model is thousands of times faster than either Cellular Automata or CFD-based simulations. • We prove why the DI01 cov-tuning diverges when the background and observation matrices have the same correlation structure. • The algorithm scheme proposed in this work can be easily applied/extended to other dynamical systems. [ABSTRACT FROM AUTHOR]