Assessment of biomass burning smoke influence on environmental conditions for multiyear tornado outbreaks by combining aerosol‐aware microphysics and fire emission constraints. Issue 17 (15th September 2016)

• Record Type: Journal Article
• Authors: Saide, Pablo E.; Thompson, Gregory; Eidhammer, Trude; da Silva, Arlindo M.; Pierce, R. Bradley; Carmichael, Gregory R.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 17(2016)
• Page Start: 10, 294
• Page End: 10, 311
• Publication Date: 2016-09-15
• Subjects: biomass burning -- severe weather -- tornadoes -- fires -- aerosol‐cloud‐radiation interactions -- WRF; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2016JD025056
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: We use the Weather Research and Forecasting (WRF) system to study the impacts of biomass burning smoke from Central America on several tornado outbreaks occurring in the U.S. during spring. The model is configured with an aerosol‐aware microphysics parameterization capable of resolving aerosol‐cloud‐radiation interactions in a cost‐efficient way for numerical weather prediction (NWP) applications. Primary aerosol emissions are included, and smoke emissions are constrained using an inverse modeling technique and satellite‐based aerosol optical depth observations. Simulations turning on and off fire emissions reveal smoke presence in all tornado outbreaks being studied and show an increase in aerosol number concentrations due to smoke. However, the likelihood of occurrence and intensification of tornadoes is higher due to smoke only in cases where cloud droplet number concentration in low‐level clouds increases considerably in a way that modifies the environmental conditions where the tornadoes are formed (shallower cloud bases and higher low‐level wind shear). Smoke absorption and vertical extent also play a role, with smoke absorption at cloud‐level tending to burn‐off clouds and smoke absorption above clouds resulting in an increased capping inversion. Comparing these and WRF‐Chem simulations configured with a more complex representation of aerosol size and composition and different optical properties, microphysics, and activation schemes, we find similarities in terms of the simulated aerosol optical depths and aerosol impacts on near‐storm environments. This provides reliability on the aerosol‐aware microphysics scheme as a less computationally expensive alternative to WRF‐Chem for its use in applications such as NWP and cloud‐resolving simulations. Key Points: WRF with aerosol‐aware microphysics is used to study smoke impacts on multiple tornado outbreaks Although smoke is always present, changes in environmental conditions due to smoke are highly variable WRF and WRF‐Chem simulations can produce similar AOD and smoke impacts