Sensitivities of WRF-Chem to dust emission schemes and land surface properties in simulating dust cycles during springtime over East Asia

The sensitivities of Weather Research and Forecasting model coupled with chemistry (WRF-Chem) to the Air Force Weather Agency (AFWA) and Shao2011 (S11) dust emission schemes, and to various land surface properties generated from United States Geological Survey (USGS) and Beijing Normal University (BNU) soil data over East Asia for spring 2012, are examined in this study. The results show that the dust emissions generated with the S11 scheme are 2-5 times that generated with the AFWA emission scheme, with emissions ranging from 0.2-1 Tg/d over East Asia in the relevant period. The AFWA emission scheme omits almost the entire Gobi desert and produces low dust emissions, whereas large amounts of dust emission in this region are produced with the S11 emission scheme, regardless of whether USGS or BNU soil data are used. The surface particulate matter 10 (PM10) concentrations are reasonably well reproduced by the model with different configurations. However, the S11 emission scheme has better performance in simulating the surface PM10 concentrations than the AFWA scheme, especially near the Gobi desert. Comparisons with satellite-based observations suggest that WRF-Chem gives better performance with S11 emission scheme in reproducing the horizontal and vertical distribution of aerosol optical properties. The discrepancy between the performances of the AFWA and S11 emission schemes is mainly due to the underestimation of the dust emission over the Gobi desert by the AFWA scheme, which scales the dust emission directly based on the erodibility factor, indicating that the erodibility factor over the Gobi desert is highly underestimated and highlighting an urgent need to improve the erodibility data set.