Toward resolution-independent dust emissions in global models: Impacts on the seasonal and spatial distribution of dust

Abstract

Simulating the emission of mineral dust and sea-salt aerosol is nonlinear with surface winds and therefore requires accurate representation of surface winds. Consequently, the resolution of a simulation affects emission and is often corrected with nonphysical scaling in coarse resolution global models. We examine the resolution dependence of emissions in the GEOS-Chem model and find that globally, annual emissions at 4° × 5° resolution are 59% of those simulated at 2° × 2.5° and only 33% of emissions at 0.25° × 0.3125°. The spatial and seasonal distribution of dust emissions vary substantially, indicating that applying a uniform scaling is inappropriate. We demonstrate the benefit of characterizing the subgrid surface wind as a Weibull probability distribution, reconciling much of the difference in emissions between resolutions for dust. Such a representation is shown to have little impact on sea-salt emissions.