Adding the impacts of biological crusts on sand and dust storm emission in Asia

Although biological crusts (biocrusts) grant stability to dust source areas by inhibiting dust emission, only a few models have explicitly considered their inhibitory effect. In this study, we used the China Meteorological Administration Unified Atmospheric Chemistry Environment/ Dust model and combined retrieved biocrust information with two biocrust inhibition schemes (roughness length and biocrust strength schemes) to study numerically the inhibitory effect of biocrusts on a strong dust storm that occurred in Central and East Asia on 25-30 Mar. 2018. The inhibitory effect of biocrusts on dust emission increased with biocrust coverage. The total dust emission forecasted by the roughness length and biocrust strength schemes was reduced by approximately 56.7% and 47.9% on average, respectively. In downstream sites in China, the surface mass concentrations of PM10 forecasted by the roughness length and biocrust strength schemes decreased by 36%-57% and 24%-41%, respectively. When biocrusts were considered, the forecast for stations near the dust source area considerably improved and that for stations distant from the source area became more reasonable but with larger bias under the combined effects of emission, transport and deposition.