一次大雾天气下PM2.5二次无机粒子的数值模拟

A Numerical Analysis of Secondary Aerosol Inorganic Particles of PM2.5 in a Strong Fog

利用多尺度空气质量模式系统(Models-3/CMAQ)对2002年12月1—3日北京及周边地区发生的一次大雾天气进行数值模拟,分析了大雾天气下PM2.5二次无机粒子的演变及其影响。结果表明,白天相对湿度降低,雾滴蒸发脱水后PM2.5二次无机粒子会悬浮在大气中;夜间在水汽凝结成雾滴的过程中,大量的PM2.5二次无机粒子提供了充足的凝结核,促进大雾天气的进一步发展。午后PM2.5二次无机粒子积聚及较高的相对湿度是造成北京及周边地区低能见度的重要原因,并推断该区域很可能是霾天气。

Fine aerosol particles （ PM2.5 ） are a kind of contamination, which can cause serious pollution. By using the multiscale air quality models system （Models-3/CMAQ）, a numerical simulation was conducted for a thick fog in Beijing and its peripheral areas on December 1--3,2002. Based on the high-resolution outputs of the model, a detailed analysis was carried out for the development of secondary inorganic particles of PM2.5 and their influence on visibility. The results show that fog gradually disappeared with decline in relative humidity and secondary inorganic particles of PM2.5 began to accumulate and suspended in the air in the daytime. At the night, plenty of secondary inorganic particles of PM2.5 facilitated the formation of fog by providing ample condensation nucleus. After noon, the accumulation of secondary inorganic particles of PM2.5 and high relative humidity were important reasons for the low visibility in Beijing and its peripheral areas. It was likely the weather of haze in these areas.