一次光化学污染过程中O_3和NOx的垂直梯度观测研究

为了研究2008年北京奥运会前期污染物浓度变化特征,对北京气象塔3层高度上的大气污染物(NO2和O3)进行加强观测,分析其变化特征。观测结果表明,由于北京奥运会前期采取了严格的空气质量控制措施,NO2浓度相对车辆限行前下降了45.3%,且随着高度递增逐渐降低;O3浓度最大值和日均值有所降低,其最大值出现时间较10年前提前了1~2 h,且有4 h左右处于相对平稳状态。O3浓度峰值主要是受NO2的控制,O3浓度峰值出现时间提前反映出北京大气氧化效率不断提高。对于观测期间出现光化学污染事件,利用同期气象资料和大气污染监测数据分析,发现造成这次大气污染的主要原因是气象因子:地面多处于弱高压场控制中,大气层结稳定,风力较弱(小于2 m/s),并伴随着连续高温、强辐射和低湿。

Studies on gradient observation of O3 and NOx in an atmospheric photochemical pollution

In order to study atmospheric pollution concentration changes during the 2008 Olympic Games in Beijing, atmospheric pollutants( NO_2 and O_3) at 3 altitude levels of Beijing meteorological tower were observed, and their variations were analyzed. The results indicate that by the strict measures for improving the air quality before Olympic Games, NO_2 concentration reduced by 45. 3% and decreased gradually with the increasing height; both the maximum of O_3 concentrations and the daily average O_3 concentrations decreased. The appear-ance time of O_3 maximum concentration was brought forward about 1～2 h than 10 years ago, and kept stably a-round 4 h. The O_3 peak concentrations were mainly influenced by NO_2. The O_3 concentration peak appeared a-head of schedule,which showed that Beijing atmospheric oxidation efficiency continued to increase. According to the analysis meteorological data and atmospheric pollution monitoring data the meteorological factors for photo-chemical pollution event were found as follows: weak-rield control of high-voltage, stable atmospheric stratifica-tion, weaker wind force ( the wind velocity was less than 2 m/s) , and accompanied by a continuous high temper-ature, strong radiation and low humidity.