Turbulence-chemistry interactions in fresh wildland fire plumes: implications from high-resolution LES-chemistry simulations

Abstract:

Wildland fires emit a wide array of trace gases and aerosol particles into the atmosphere, affecting the air quality, human health, and global climate. The chemical evolution of the wildland fire plumes remains poorly understood, partially due to the complex entangle between fire-induced turbulence and chemistry. In this work, a high-resolution large eddy simulation (LES) in the WRF package (WRF-LES) is coupled to chemistry to study the physical and chemical evolution of a fresh wildfire plume. The plume rise is driven by the heat release from the fire source, rather than empirical parameterizations widely used in other models. The chemical mechanism includes conceptual O3/NOx/VOC/aerosol chemistry to mimic the chemical evolution in fire plumes, with special focus on HOx radicals, HONO, and PAN. The model online calculates photolysis frequencies using FTUV, considering the impacts of fire-emitted aerosols. This work is focusing on the following aspects: (1) Impacts of turbulence and plume dynamics on chemistry. (2) Oxidative capacity within fire plume: core vs edge. (3) Plume physical and chemical ages. This theoretical study also provides implications for airborne data analysis, as well as the fire emission parameterization in 3-D air quality and chemistry-climate models.