Parameterizing agricultural fires inducing mineral dust emission

• Applicant: Professorin Dr. Kerstin Schepanski
• Subject Area: Atmospheric Science
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 432456920

Aerosol, tiny particles suspended in the atmosphere, is ubiquitous in atmosphere and takes part in many climate-relevant processes determining the Earth energy budget and ultimately the Earth thermostat. However, large uncertainties are still associated with aerosol source description, emission, and feedback processes limiting the accuracy of Earth system models and climate projections.Aerosol is divers regarding its sources, properties and impact. Natural aerosol is emitted from natural sources like deserts where bare soil is prone to wind erosion. Carbonaceous combustion aerosol is emitted from wild fires fueled by vegetation. Both mineral dust aerosol particle, entrained into the atmosphere by wind, and carbonaceous aerosol injected into the atmosphere by the fire's pyro-convective updraft, is a naturally occurring process, but can also be induced by human activity. E.g. agricultural land use can increase the land surface's susceptibility to wind erosion. Land management practices such as prescribed fires lit to burn-off vegetation residues significantly contribute to the local atmospheric burden of combustion aerosols. Furthermore, the burn-off of vegetation residues increases the wind erosion potential in two ways: First, the removal of vegetation increases the surface's susceptibility to wind erosion. Second, the pyro-convection enhances the ambient wind field and increases the atmospheric turbulence, which increases the wind-driven dust entrainment.In the light of the complexity of environmental conditions and processes controlling and driving natural aerosol emission, investigations on the emission process and its accurate representation in mathematical-physical models is inevitable. Although individual parameterizations for different aerosol emission processes exists, they are used mutually independent. The joint consideration is in particular relevant for prescribed fires in agricultural regions, where the vegetation otherwise inhibits wind erosion. To address this missing link, the project aims at developing a parameterization suite describing mineral dust emission induced by agricultural fires, which will be tested for south-east Australia. There, agricultural fires and wind erosion are common phenomena.

• DFG Programme: Research Grants