Representations of dynamics size distributions of mineral dust over East Asia by a regional sand and dust storm model

摘要

Particles larger than 5.0 μm in diameter are important to keep the size distribution for mineral dust but it is difficult to represent them in numerical models due to the complex emission process and quick gravitational deposition. To improve this situation, the cumulative distribution function of the Weibull distribution is used to represent the instant wind larger than the model grid-mean wind speeds of the sectional dust forecast model, China Meteorological Administration Unified Atmospheric Chemistry Environment/Dust (CUACE/Dust). Size distributions for dessert soil texture in China and mass median diameters for the three lognormal populations of dust flux released are also improved from observations in Asian source areas. With all these updating, the mass size distribution of dust flux from the model is much closer to the observed value, which changes the original unreasonable single-peak distribution, coming close to the distribution trend with increasing particle size bins. It then improves the emission for coarse particles larger than 10.0 μm in source areas. Moreover, both the varied values and changing shape patterns of column volume particle size distributions simulated in the downwind areas compatible to the observed by the global AErosol RObotic NETwork (AERONET) achieving an obvious improvement for the size distribution of coarse particles larger than 5.0 μm in these downwind areas.