Urban air quality and regional haze weather forecast for Yangtze River Delta region

Air pollution and haze weather have become more and more important environmental and meteorological issues in Yangtze River Delta (YRD) region of China. In order to foster urban and regional air quality management and realize operational prediction and early warning of air pollution and haze weather episode, an urban air quality forecasting system based on the new generation of weather research forecast and chemistry model WRF-Chem and a regional haze weather forecasting system based on Regional Atmospheric Environment Modeling System (RegAEMS) were applied in Shanghai, Nanjing and YRD area. More than one year runs and typical case studies show that WRF-Chem performed well in urban air quality forecast on surface concentrations of air pollutants such as SO2, NO2 and PM10. The accuracy rate of prediction on urban Air Pollution Index (API) is 50–83% and 80% for Shanghai and Nanjing, respectively. RegAEMS presents relatively good ability in forecast on regional haze weather. A new classification standard on haze level was proposed, which take the key parameters such as relative humidity, PM2.5 and visibility into account. It is estimated that RegAEMS predicts haze level with accuracy rate of 58 and 77% for Nanjing and Shanghai in YRD region. Many factors, including meteorology, emission inventory and chemical processes can be attributable to the forecast bias. However, from this study, it is highly suggested that improvements of emission inventory from construction dust, fugitive dust, soil dust, transportation and biomass burning are very crucial to get better performance on air quality and haze weather prediction.