Modeling of Mineral Dust Emissions with a Weibull Wind Speed Distribution Including Subgrid-Scale Orography Variance

Abstract

AbstractThe modeling of mineral dust emissions requires an extensive knowledge of the wind speed close to the surface. In regional and global models, Weibull distributions are often used to better represent the subgrid-scale variability of the wind speed. This distribution mainly depends on a k parameter, itself currently parameterized as a function of the wind speed value. In this study we propose to add the potential impact of the orography variance in the wind speed distribution by changing the k parameter value. Academic test cases are designed to estimate the parameters of the scheme. A realistic test case is performed over a large domain encompassing the northern part of Africa and Europe and for the period 1 January?1 May 2012. The results of the simulations are compared to particulate matter (PM10) surface concentrations and Aerosol Robotic Network (AERONET) aerosol optical depth and aerosol size distribution. We show that with the orography variance, the simulation results are closer to the ones without variance, showing that this additional variability is not the main driver of possible errors in mineral dust modeling.