Demonstration of Navy's operational dust storm forecasting for Southwest Asia

Real-time dust forecasting using US Navy's Coupled Ocean-Atmospheric Mesoscale Prediction System (COAMPS) with an inline dust aerosol model is being conducted by US Fleet Numerical Meteorology and Oceanography Center. Daily forecasts of dust concentration, visibility and optical depth are produced out to 72 hrs on nested grids of 9, 27 and 81 km with two-way nest interaction. A high-resolution dust source database has been developed to support the dust forecasting in this region. Dependence of dust prediction on source resolution is studied in an Afghanistan storm by using different databases to prove the importance of accurate representation of fine source points and streaks. Parallel dust forecasts of single-bin and multi-bin modeling are performed in simulating a severe storm over the Arabian Peninsula to compare the similarities and differences between forecast products and provide evidence for the choice of the optimal number of bins in operations. The model performance is evaluated for a special period of the Iraq War in the spring of 2003 using ground weather reports, visibility observations, and enhanced satellite retrievals. The verification shows COAMPS predicted the arrival and retreat of major dust events within 2 hours, the intensity of storms (reduction in visibility) with an error of less than one kilometer, and the spatial distribution of dust fronts and plumes being consistent with observations. An extensive statistical analysis of dust-related visibility is conducted to examine the model bias, RMS and relative errors, as well as forecast rates and threat score. Overall COAMPS predicted more than 85% of the observed dust and non-dust weather events in the evaluation period.