The Uncertainties of Asian Dust Forecasting over Taiwan During Spring 2002

This research coupled meteorological model, regional air quality model and incorporated dust module to forecast the arrival time, concentrations and impact areas of Asian dust over Taiwan during year 2002. Taiwan Air Quality Model was the 3-D Eulerian air quality model applied in this forecasting system, in which the outputs of hourly meteorological data obtained from Penn State/NCAR Mesoscale Model were used as inputs, and a dust module was developed and incorporated. The physical processes of dust including emissions, transport, diffusion, depositions were considered, and the dust emissions from Wang et al.­]2000­^were adopted. The system automatically forecasted the dust concentrations within the next 4 days over the East Asia nearby Taiwan during February to May. The results indicated that the predicted and observed dust arrival time were within several hours of discrepancy, and the initial and boundary conditions of MM5 obtained from the global model outputs from National Centers for Environmental Prediction (NCEP) significantly affected the forecasting ability. The predicted dust concentrations were determined by the parameterization of dust emissions as well as the transport mechanisms in the air quality models. The mechanisms of the dry and wet depositions, and the model horizontal and vertical resolutions were also important factors to affect the forecasting ability and will be discussed.