Modeling study of Asian dust: Assessment of various dust emission schemes using WRF/Chem

Many dust emission schemes have been developed to simulate dust events. They produce dust phenomena reasonably. However, the amounts of simulated dust emission are much different among various dust emission schemes. It is required to assess different dust emission parameterizations and their effects on dust simulations for developing dust models.

This study intends to investigate recent dust emission schemes in detail and compare them under the same numerical and meteorological conditions by implementing several dust emission parameterizations into WRF/Chem. We implemented two different parameterizations for the following procedures: calculation of threshold friction velocity, soil moisture correction, roughness element correction, and horizontal sand flux. For the vertical flux, three well-known dust emission parameterizations, namely, those of Marticorena and Bergametti (1995), Lu and Shao (1999), and Shao (2004) were implemented into WRF/Chem.

Sensitivity tests for soil moisture, vegetation cover and soil texture type were conducted to identify the influence of the input parameters in the calculation of dust emission amounts, and step-by-step comparisons of different parameterizations were carried out. Using observation data from the Japanese Australian Dust Experiment (JADE), comparison between calculated horizontal sand flux from several parameterizations and observed sand flux was conducted. Model simulations were performed for a severe Asian dust event that occurred in the spring of 2007 to evaluate various dust emission schemes and model results were compared with observation data such as satellite data and PM10 concentration.