用MM5模式和阻力模型计算硫化物的干沉降速度

使用NCEP资料，由中尺度气象模式MM5产生中国东部及附近地区详细的边界层气象场，使用类似于RADM中的阻力模型，计算了该地区2000年3月22—27日硫化物(SO2、SO4^2-)的干沉降速度的区域分布，以及典型地区的干沉降速度随时间的演变；讨论了不同阻力对硫化物干沉降速度的影响．结果表明：随着下垫面类型和气象条件的不同，硫化物的干沉降速率有着明显的时空变化，尤其是当有天气系统(如锋面)时，污染物的干沉降速率明显增大．对SO2来说，不同的下垫面条件、不同的气象条件下，三种阻力的相对重要性不同；对SO4^2-来说，其干沉降速度主要决定于分子扩散阻尼和表面阻尼．

SO2 and SO2-4 Dry Deposition Velocities Computed Using Resistance Model and MM5

The spatial and temporal distribution of SO 2 and SO 2- 4 dry deposition velocities under typical weather conditions over eastern China and the neighboring areas were calculated using the resistance model and the detailed meteorological fields in the boundary layer produced by the mesoscale meteorological model MM5, and the effects of different resistances on the dry deposition velocities were discussed. It was found that the SO 2 and SO 2- 4 dry deposition velocities have obvious spatial and temporal variations with changes in the underlying and meteorological conditions. When there are intensive weather systems, the dry deposition velocities increase notably. As for SO 2, with different underlying surface and meteorological conditions, the relative importance of the three resistances are different, while the dry deposition velocity of SO 2- 4 is mainly decided by the molecular diffusion resistance and the surface resistance.