海岸地区空气污染物输送与扩散的数值模拟

本文建立了求解三维扩散方程的数值模式,以经过处理地形影响经连续方程调整模式计算得到的三维风场和实测铅直湍流扩散系数作为输入,模拟了沿海城市秦皇岛地区海陆风演变过程中空气污染物(SO_2)浓度的时空分布(x-y和y-z两个剖面)。模式的数值求解,在水平方向采用伪谱方法,铅直方向采用上游格式和六点格式,对三维扩散方程运用分步求解的数值方法,用计算所得的地面SO_2浓度分布和实测值比较,一致性相当好。显示在早晨和傍晚出现极大值,午后出现极小值。计算所得的日平均浓度与实测结果相比,也相当吻合。分析表明,本文所建模式行之有效,且数值计算稳定性表现良好。

NUMERICAL SIMULATIONS OF ATMOSPHERIC POLLUTANT TRANSPORT AND DIFFUSION IN THE COASTAL REGION

In this paper, a 3-dimensional numerical model was set up and used to compute the surface concentrations of SO₂ in the coastal region of Qinhuangdao city as the land-sea breeze prevailing. The atmospheric diffusion equation was solved by using the method of fractional steps, the techniques used to represent terms involving the derivatives in the spatial coordinates of these differential equation including; pseudospectral method in horizontal, upstream and Crank-Nicolson method in vertical. The computed 24-hour averaged surface concentrations of SOZ over this region showed a good agreement with the observed values. The computed tendency of diurnal variation of SO₂ concentrations at port station coincides fairly well with observational ones. The analysis showed that the performance of the model in this paper is good and numerical calculation is stable.