Wildfire impact on environment thermodynamics and severe convective storms

Tuesday, December 11, 2018 - 08:00
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Wildfire is one type of climate extreme, and its frequency, burning season and area have been increasing globally. Besides a globally important source of aerosol particles that could impact cloud, precipitation and radiation, biomass burning heats the environment dramatically and could significantly perturb the environment thermodynamics if the burned area is large. However, this impact on environment thermodynamics and the subsequent severe convective storms has never been investigated. In this study, we developed a model capability for the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) by considering the heat fluxes from wildfires into the atmosphere. We evaluate our model development with several wildfire events in simulating the thermodynamics observed from soundings. Particularly, we conduct model simulations for the Mallard fire pyrocumulonimbus event occurring in Texas and Oklahoma on May 11-12, 2018, to explore how the large fire that began in early May in the region modify the thermodynamics of atmosphere and aerosol properties and how these changes affect the initiation and development of the pyrocumulonimbus clouds, which produce quite amount of hailstone and lightning. We evaluate our model simulations with observations from radar, sounding and satellite measurements. With the thermodynamic effect of fire plume considered, the initiation and the intensity of the convection is much better simulated, which suggests the importance of the impact of wildfire to environment thermodynamics and the severe storm development.

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