Impact of Transport Schemes on Modeled Dust Concentrations

Abstract

A sensitivity study is performed with the CHIMERE-DUST chemistry transport model in order to evaluate the modeled mineral dust spread due to the horizontal transport scheme accuracy. Three different schemes are implemented in the model: the simple first-order UPWIND scheme, the second-order Van Leer scheme, and the third-order parabolic piecewise method (PPM) scheme. The results showed that a large part of the uncertainty in dust modeling may be due to the transport scheme only. Compared to the PPM scheme, it is shown that, over a large domain encompassing western Africa and the North Atlantic, a significant increase in the dust plume extension is locally diagnosed (+25% with Van Leer and +48% with UPWIND) and linked to a decrease in the dust maxima (?17% with Van Leer and ?32% with UPWIND) to PPM. Far from the sources, hourly surface concentration differences may be up to 30 ?g m?3 in Europe, highlighting the high uncertainty of dust modeling for air quality use.