上海市气象场与SO2浓度数值模拟

采用地形坐标系下适合于复杂地形且满足地-气耦合的静力学三维中-β尺度气象预报模式,使用08时的实测流场经变分法初始化后得到的初始流场,模拟研究了上海地区的局地流场时空演变特征。模式较细致地考虑了湍流、长短波辐射、凝结、蒸发、地表热力平衡等因子,在此基础上,使用有限元法数值求解一阶闭合的三维欧拉平流扩散方程,模拟了上海地区的SO₂浓度分布。结果表明:上海的局地流场具有明显的日变化特征,受海陆温差的影响明显,日间风速较夜间风速大,风向呈顺时针旋转;在不稳定层结情况下,高架点源排放的高空污染物对地面的污染物浓度有贡献,会造成地面污染物浓度升高。

Numerical Simulation of Meteorological Fields and SO2 Concentration in Shanghai

The temporal and spatial variation characters of local flow fields in Shanghai are simulated and investigated in this paper by using the 0800 BST observed meteorological element fields as the initial fields and by employing a 3-D terrain-following coordinate atmospheric meso-β scale hydrostatic model,in which some physical processes are considered in detail such as turbulent excharge,long-and short-wave radiation,condensation,evaporation and surface heat energy budget.Then the Eulerian advection-diffusion equation solved by the finite element method is used to simulate the distribution of sulphur dioxide concentration.The results show that the local flow fields exhibit a distinct diurnal variation,and are obviously affected by the sea-land temperature differences;the wind velocity in day time is greater than that at night and the wind rotates clockwisely from daytime to night;under the condition of unstable stratification the air pollutants from elevated point source can be transported to the ground leading to an increase in the surface SO₂ concentration.