Reducing Resolution Dependency of Dust Emission Modeling Using Albedo-Based Wind Friction

Abstract

Numerical simulations of dust emission processes are essential for dust cycle modeling and dust-atmosphere interactions. Models have coarse spatial resolutions which, without tackling sub-grid scale heterogeneity, bias finely resolved dust emission. Soil surface wind friction velocity (us*) drives dust emission non-linearly with increasing model resolution, due mainly to thresholds of sediment entrainment. Albedo is area-integrated, scales linearly with resolution, is related to us* and hence represents its sub-grid scale heterogeneity. Calibrated albedo-based global dust emission estimates decreased by only 2 Tg y−1 (10.5%) upscaled from 0.5 to 111 km, largely independent of resolution. Without adjusting wind fields, this scaling uncertainty is within recent estimates of global dust emission model uncertainty (±14.9 Tg y−1). This intrinsic scaling capability of the albedo-based approach offers considerable potential to reduce resolution dependency of dust cycle modeling and improve the representation of local dust emission in Earth system models and operational air quality forecasting.