Wildfires play an important role in the Earth climate system by means of complex two-way couplings with climate change. Climate change is expected to increase the wildfire risk under various future scenarios. Although its importance is widely recognized, the fidelity of wildfire simulations remains relatively poor due to large uncertainties in the current global Earth system models (ESMs) and observational datasets. The major factors include (but not limited to) the coarse grid spacing and resolved dynamics of global ESMs, the missing physical representations (e.g., chemistry and aerosols), and deficiencies in the fire emission estimations.

In this study, we built a new global multiscale simulation framework integrating the cutting-edge developments of climate modeling and observational data to provide the end-to-end testbed capabilities considering these highly uncertain wildfire aspects. Leveraging on our diverse and specialized team, we are able to simulate large (i.e., generated pyrocumulonimbus) California wildfire events with the observationally constrained emissions and surface forcings, convection-permitting (a few kilometers) scale dynamics, and interactive chemistry and aerosols, and evaluate these wildfire simulations against high-frequency satellite datasets. The main developments consist of 1) hourly high-resolution (500 m) fire emissions, perimeters, and surface forcings based on VIIRS satellite measurements, 2) convection-permitting simulations in California extended from the Energy Exascale Earth System Model regionally refined model, 3) improved chemistry and aerosol treatments (e.g., fully interactive chemistry in troposphere and stratosphere and brown carbon), 4) plume rise parameterization, and 5) the dark target GEO_LEO merged satellite aerosol product.

Here we will present the results for a few recent wildfires in California, such as the 2020 Creek fire and the 2021 Dixie fire. These initial results show encouraging hints, and we hope to gain more understanding and insights of wildfire with this end-to-end framework in the follow up studies.

This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-852479