Parameterization schemes on dust deposition in northwest China: Model validation and implications for the global dust cycle

Abstract

Accurate estimation of dust deposition is of significance for modelling global radiation and the biochemical carbon cycle in the earth system. However, the paucity of dust deposition data precludes our ability to adequately verify estimations of dust deposition. Based on the environmental monitoring records in Xinjiang Province, northwest China, we conducted a numerical simulation of dust deposition using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) and compared observed and modelled deposition during the spring dust season (March–May). The performance of WRF-Chem on modelling dust deposition was tested and evaluated with adoption of Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) and Shao et al. (2011a) dust emission schemes. Our results indicate that the dry deposition schemes have the capability to predict size-resolved dust deposition. However, modelled and measured dust deposition differed by more than one order of magnitude. The modelled dust dry deposition does not satisfactorily agree well with field measurements. This study suggests significant distinctions exist among these two dust emission schemes when simulating mineral dust dry deposition in northwest China. Uncertainties in estimating the dry dust deposition are in a range of 77–96%. These uncertainties imply that parameterization in the current dust deposition schemes need to be further improved. We found that the estimation of dust deposition is highly underestimated by the Global Climate Model and Regional Climate Model (GCM/RCM). Thus global dust cycles and dust deposition may exceed our current estimates.