Numerical Dust Models

Abstract

Models of dust emission, transport and deposition are used as a tool to understand the various aspects that control distributions and impacts of dust. While global models of the dust cycle are used to investigate dust at large scales and long-term changes, regional dust models are the ideal tool to study in detail the processes that influence dust distribution as well as individual dust events. Simulating dust emissions, which depend non-linearly on surface wind speed, is a critical issue in dust transport models. Surface wind fields used to compute emission fluxes must be available at appropriate resolution to resolve the processes responsible for dust emissions. A major problem in model-based assessments of dust effects is that atmospheric models are often unable to reproduce the small-scale wind events that are responsible for a large part of dust emission. Recent satellite-retrieved surface roughness data for desert regions considerably improve dust emission computations. Model intercomparison studies highlight that the averages and seasonal variability of vertically integrated mineral dust parameters like optical thickness and Angstrom exponent agree within a factor of two with observations. Less agreement is found for surface concentration and deposition fields of mineral dust particles.