Numerical Simulation of Chemical Process in Stratiform Precipitation
ZHANG Yuanbang;ZHANG Xingjun;LI Jinlong(Center of Environmental Scicnces,Peking University,Beijing 100871)QIN Yu(Department of Geophysics,Peking University,Beijing 100871)
A more detailed chemical process involved in an one-dimensional,time-dependent,physi-cochemical model of stratiform clouds is studied.The transmission process between gaseous and aque-ous phases, he transformation of cloud water to rainwater and the collision process are deaIt with by means of chemical equations. Based on the above approach the acidification of precipitation and wet re-moval of pollutants are simulated.The numerical tests show that the concentrations of components in the upper cloud and rainwater decrease with time gradually,but to the rainwater on the ground,it has peak profiles. In later precipitation the pH of rainwater depends mainly on the concentrations of O_3 and SO_2. In rainwater,the majority of results from aerosols,from NH3 gas,and from gases and aerosols equally.In average,the below-cloud scavenging of ,,or has a proportion between 60%and 80%.The oxidation of S(Ⅳ)by H_2O_2 is more im-portant than that by O_3 in initial precipitation,but less important in late precipitation.