Abstract: Based on data from a comprehensive atmospheric dispersion experiment of high temporal and spatial resolution over a complex hilly-valley area in Hunan province, the applicability of USEPA (United States Environmental Protection Agency) recommended guideline model CALPUFF (California Puff Model) in near field over complex terrain was investigated. Using diagnostic wind fields of different temporal resolutions and various dispersion schemes, the near-field concentration distributions under various meteorological conditions were simulated and compared with the observed tracer concentrations. The results show that using the measured turbulence profiles to calculate dispersion parameters can better simulate near-field concentration distributions. The modeling results can be improved if the fitted relationships between standard deviations of turbulent velocities and stability parameters are used instead of the default CALPUFF turbulence parameterization scheme. The modeling results are not sensitive to the temporal resolution of wind fields and dispersion schemes when the wind speed is high and wind direction is steady. However, under low and variable wind conditions, the 10 min wind field is needed to model the ground concentration distributions. The modeling results of measured turbulence scheme are higher than those of similarity scheme and closer to the observed values. Overall, CALPUFF modeling system can well simulate the near-field peak concentrations over this hilly-valley complex terrain by using either the hourly wind field and turbulent measurement or 10 min wind field and modified similarity scheme.

Key words: CALPUFF model, complex terrain, near-field concentration distribution, atmospheric dispersion experiment

摘要： 利用在湖南省丘陵河谷地区开展的高时空分辨率大气扩散综合实验资料, 研究美国国家环保局(USEPA)推荐的导则模式CALPUFF (California Puff Model)在复杂地形条件下近场应用的适用性。采用不同时间分辨率的诊断风场和不同扩散参数计算方案, 模拟不同气象条件下的近场地面浓度分布。通过与示踪实验实测采样浓度对比分析, 得到: 采用实测湍流廓线资料计算扩散参数能够较好地模拟近场浓度分布; 将实测湍流速度标准差与稳定度参数的拟合关系替代CALPUFF默认的湍流参数化方案, 能够改进默认相似性理论方案的模拟结果; 风速较大、风向稳定时, 模拟结果对风场的时间分辨率和扩散参数计算方案的敏感性较弱; 风速较小、风向多变时, 需采用逐10 min风场模拟地面浓度场分布, 且实测湍流方案模拟结果相较于相似性理论方案模拟值偏大, 并更接近实测值。总之, 采用逐时风场和实测湍流方案, 或逐10 min风场和修正后的相似性理论方案的CALPUFF模式能较好地模拟研究区域复杂地形的近场峰值浓度。

关键词: CALPUFF模式, 复杂地形, 近场浓度分布, 大气扩散实验