天津大气污染物日变化特征的WRF-Chem数值模拟

Numerical simulation of diurnal variation of major pollutants with WRF-Chem model in Tianjin

利用大气化学完全耦合模式WRF-Chem对天津市环境空气中特征污染物CO、NOx、O3、PM2.5的时间变化规律和空间分布特征进行了数值模拟研究,并与实际观测资料进行了对比.结果表明,天津市CO、NOx、O3、PM2.5具有明显的时空变化特征:O3浓度在中午出现最高值,夜间浓度较低;NOx、O3、PM2.5在晚上和清晨出现高浓度,午后至傍晚浓度较低.O3在空间分布上表现为中午市区比郊区浓度高,夜间郊区浓度高.其他污染物则均表现为市区浓度高于郊区.在当日东北风情况下,周边地区对天津市污染的影响较小,4类污染物主要是受本地源的影响.

The numerical simulation of the temporal variation and spatial distribution of the concentrations of CO, NOx, O3 and PM2.5 were conducted with WRF-Chem model in Tianjin. The uncertainties of the model were evaluated by comparing with the observed data. The temporal variations and spatial distribution of the concentrations of CO, NOx, O3 and PM2.5 were significant in Tianjin area. Concentrations of O3 were higher at noon and lower at night, while concentrations of CO, NOx and PM2.5 were higher in the morning and night, and lower in the afternoon. In addition, concentrations of O3 in urban area were higher than it in suburban area in the early afternoon, but the reverse was true at nighttime. The concentrations of CO, NOx and PM2.5 in urban area were higher than it in the suburban area all the time. On the typical day with the northeastern wind, the four pollutants above were mainly from the local sources, the long distance transportation of these pollutants was insignificant.