层状云酸化过程的数值模拟

Simulation of Acidification of Stratiform Precipitation

修正和发展了一维层状云物理化学模式，该模式包括了详细的气、液相反应和光辐射传输，在我国东部地区平均污染水平下模拟了降水酸化过程。结果表明：光解系数在云顶为无云时的２～３倍，在云底则为无云时的０．２倍；自由基对Ｓ（Ⅳ）的氧化在降水后期可超过Ｈ２Ｏ２，并致使ＳＯ２－４和ＮＯ－３浓度在降水后期有逐渐增长的趋势；由于Ｈ２ＳＯ４和ＨＮＯ３的不断生成以及ＮＨ３和气溶胶的洗脱，地面雨水酸度持续上升。

D physicochemical stratiform cloud model was modified and developed to couple with gaseous and aqueous chemical mechanisms as well as with radiation transfer. Precipitation acidification is simulated under the condition of average polluted atmosphere in Eastern China by using this model. The results show that the photolysis coefficient has a factor of 2 3 at cloud top and only 0.2 in cloud base, compared with that in cloudless condition. The role of radical to oxidize S(Ⅳ) in precipitation is exceed H 2O 2, which results in sulfate and nitrate concentration increasing gradually in later term of precipitation. Thus ground rainwater is getting more and more acidic due to continuous production of H 2SO 4 and HNO 3 and washout of NH 3 and aerosol.