CMAQ-DDM-3D在细微颗粒物(PM_(2.5))来源计算中的应用

Application of CMAQ-DDM-3D in the source analysis of fine particulate matter (PM_(2.5))

应用MM5(Fifth-Generation NCAR/Penn State Mesoscale Model)-Models-3/CMAQ(Community Multi-Scale Air Quality)空气质量模拟系统对京津冀地区进行了模拟,分别采用Brute Force方法和DDM-3D(Decoupled Direct Method in 3 Dimensions)技术对两个代表性城市石家庄、北京的PM2.5来源进行了分析计算.结果表明,两种方法的计算结果具有显著相关性,相关系数在0.950～0.989之间;其次,在某一地区浓度贡献较低的情况下,两种方法的计算结果非常接近,但随着浓度贡献的增加,Brute Force方法的计算结果逐渐高于DDM-3D方法,直线拟合的斜率在1.14～2.05之间.以石家庄为例,Brute Force和DDM-3D方法估算的河北南部地区排放的浓度贡献分别为54.7%和64.4%,相差10%左右.浓度贡献空间分布的对比表明,Brute Force方法计算出的浓度影响范围更大,出现某些离散的负值点,或某些负值点与很大的正值点相邻,反映了数值计算带来的计算误差;相比之下,DDM-3D方法的计算结果则更为合理.

MM5 （Fifth-Generation NCAR/Penn State Mesoscale Model）-Models-3/CMAQ （Community Multi-Scale Air Quality） air quality modeling system was applied to simulate the air quality over the Beijing-Tianjin-Hebei area. The Brute Force and DDM-3D （ Decoupled Direct Method in 3 Dimensions） method were used to estimate the regional contributions to PM2.5 in Shijiazhuang and Beijing, respectively. The resuhs indicate that there is a high correlation between the two methods, with the correlation coefficients ranging between O. 950 to 0. 989. Second, the results of the two methods are quite close when the contribution from one region is relatively low. Along with the increase of the concentration contributions, the results of Brute Force method are increasingly higher than those of DDM-3 D ; the slope of the linear fitting is between 1.14 to 2.05. For example, Brute Force method estimates emissions from southern Hebei area contribute around 54.7% of the PM2.5 in the Shijiazhuang city, while DDM-3D method estimates around 64.4%. Moreover, Brute Force method indicates a larger impacting area, and it brings discrete negative points and some of these points are close to large positive numbers, indicating numerical errors in the model calculation. In comparison, the DDM-3D results are more reasonable.