地形数据输入范围对AERMOD预测结果的影响

Impact of Input Range of Terrain Data on the AERMOD Prediction

为验证复杂地形条件下地形数据输入范围对AERMOD模型预测结果的影响,试验分别给定1个10 m低架源和1个100 m的高架源,在输入10 km×10 km、15 km×15 km、20 km×20 km 3种范围地形数据,其他参数不变的条件下,计算污染源在同样的10 km×10 km区域内小时值、日均值、年均值落地浓度的变化。结果表明,地形数据输入范围的不同对AERMOD模型计算出的污染物落地浓度预测结果有着显著的影响,试验结果中变化的网格点最大占到总网格点的23.96%,变化幅度最大可达99.96%。在某些情况下,很有可能使得部分敏感点计算结果从达标变成超标,从而造成大气环境影响评价结论的误差。通过对AERMOD和AERMAP公式的分析可知,地形数据输入范围对AERMAP确定的受体山体控制高度有一定影响,造成了AERMOD临界分流高度和烟羽权重参数计算值的变化,从而影响了AERMOD对受体处浓度的计算结果。

To examine the impact of terrain data domain difference on the output of AERMOD＇s complex terrain predictions, the concentration in 10 km×l0 km of discharged pollutants are calculated by the AERMOD model assuming a 10 m and a 100 m point source under certain conditions. Subsequently, terrain data domain is changed from 10 km×l0 km to 15 km×15 km and 20 km×20 km for model recalculation. And the model gives an array of dissimilar results, 23.96% of all grid points change and the biggest concentration change is 99.96% in the worst case. In some conditions, it is likely making the concentration of some grid points become excessive. According to the description of the formulas of the AERMOD model, that changing terrain data domain may vary the hill height scale in AERMAP＇s output. The hill height scale change can cause the variation of the critical dividing streamline height and plume state weighting function, which ultimately influences the values of concentration.