黄山地区气溶胶吸湿增长特性数值模拟研究

Numerical simulation study on hygroscopic growth of aerosols in Huangshan area

应用多种化学组分气溶胶的绝热气块分档模式,对2008年春季黄山地区气溶胶吸湿增长特性进行了模拟分析。结果表明:黄山地区气溶胶吸湿增长因子f的大小与粒子半径、相对湿度、粒子化学组分、上升速度及上升高度密切相关,且小粒子吸湿增长比大粒子显著。吸湿增长因子与相对湿度呈正相关,相对湿度越接近粒子的临界饱和比,吸湿增长因子变化越显著。可溶性有机气溶胶,通过增加溶液中溶质的百分比来影响临界饱和比,使吸湿增长因子增大。若不考虑不可溶粒子的成核作用,会高估粒子的吸湿性。随着上升速度增大,吸湿增长因子降低,降低程度与粒子初始高度的相对湿度有关。上升高度通过改变气块相对湿度的变化来影响气溶胶吸湿增长因子。

By using adiabatic air parcel method of multi-component aerosols, this paper analyzes hygroscopic growth characteristics of aerosols in Huangshan area in 2008. Some calculations show that The hygroscopic growth factor f defined as d p, wet/d p, dry, where d p,wet is the particle mobility diameter under a humidified condition, is closely bound up with particle radius, relative humidity （RH）, particle chemical components, vertical velocity and lifting height. The hygroscopic growth of small particles is more significant than that of the large ones. Relative humidity is positively related with the hygroscopic growth factor f. The more relative humidity approaches the critical relative humidity of particles, the more the hygroscopic growth factor f changes with relative humidity. Through increasing the solute soluble inorganic aerosol influences critical saturated ratio so as to make the hygroscopic growth factor f increase. If the role of unsolvable nucleation doesn＇t be taken into account, the hygroscopic growth of particles will be overestimated. With the velocity rising, the hygroscopic growth factor reduces, and the reduction degree depends on initial relative humidity. The lifting height can influence the hygroscopic growth factor through the change of relative humidity.