Development of a region-specific wildfire scheme in the Community Land Model of the CESM

Abstract:

Wildfire is a key perturbation in the earth system to modulate climate variability by changing emissions and energy budget. Fire activities show broad spatial and temporal variability with distinct regional and seasonal characteristics. To improve modeling capability for fire activities, we newly developed a region-specific fire model with emission estimation and plume rise module in the latest Community Land Model (CLM) of the Community Earth System Model (CESM). Using the observations in the past decade, we improve the fire model by applying natural and socioeconomic constraints for fire occurrence and spread separately for 14 regions and as a function of major Plant Functional Type (PFT) categories. We then add an emission module into the fire model that accounts for the interactions between fire activities and climate variability. Plume rise processes are also incorporated into this emission module for better vertical allocation of aerosol emissions from fires, which are important for simulating long-range transport of fire aerosols and their climate effects. Observation-based evaluation of simulation results using the new fire model demonstrates enhanced modeling performance for both global intensity and regional variability of wildfires, which lay the foundation for investigating wildfire feedback to regional and global climate. The impacts on improving the modeling capability of assessing the radiative forcing of fire aerosols are assessed.