Numerical study on bioaerosol dispersion over southeast coast of China
东南沿海生物气溶胶的扩散模拟研究

In this study, the Offshore and Coastal Dispersion (OCD) was nested in a regional dispersion model and then integrated in the Regional Air Quality Model System (RegAQMS). Meteorological and turbulent fields needed for RegAQMS were calculated with the Weather Research and Forecasting (WRF) model and the Atmospheric Boundary Layer model, respectively. The process of dry deposition, wet scavenging, temperature decay, humidity decay, biological aging, and ultra-violet radiation decay of bioaerosols were also incorporated into RegAQMS to describe distribution patterns of bioaerosol concentrations. In the case study of July and August 2008 at southeast coast of China, sensitivity tests of physical and biological process of foot-and-mouth virus were conducted with the improved RegAQMS and the simulated virus concentrations were used for risk and infection assessments. Results of sensitivity tests showed that the average surface concentrations in July and August reduced by 61.9% and 65.6%, respectively, and the contaminated areas reduced by 25.6% and 50.1% if all biological and physical processes were taken into account. Temperature decay was the principal process which affected virus concentration in summer. Biological aging, dry deposition, and wet scavenging were also significant. Relative humidity however had little influence on the concentration. Results of risk and infection assessments showed that most of the research areas were safe or at low level of risk, as reported by previous study. The areas with high level of risk were small, which primarily concentrated at the downwind of two dominating flow directions in the form of narrow strips. The areas of risk regions in July and August were 61.6% and 54.2%, respectively. Infection regions accounted for less than 1% of the whole research region. Ordered flow fields from inshore water and strait terrain contributed to a small diurnal fluctuation of wind direction and horizontal turbulent intensity, which resulted in wider virus diffusion and higher infection risk.