北京近地层O3、NOx、CO及相关气象因子的分析

Analysis of O_3, NO_x, CO and correlation meteorological factor at the ground layer in Beijing

利用2004年9月——2005年7月北京市区近地层O3、NOx、CO和气象要素的连续观测资料,分析了近地层O3及其前体物体积分数的分布特征和日变化特征,同时采用非参数统计方法分析了近地层O3及其前体物体积分数的季节变化特征及局地气象要素对它们的影响。结果表明,CO和NO2的体积分数近似于Lorentz分布;O3、NO和NOx的体积分数满足指数分布。O3体积分数的日变化呈单峰型结构,午后15:00左右出现峰值,凌晨7:00左右出现最低值;而其前体物NOx和CO体积分数的日变化呈双峰型结构,早上7:00左右出现第一次峰值,午后15:00左右达到最低值,凌晨0:00左右出现第二次峰值;NO2第一次峰值的出现时间滞后于NO和CO;此外,NO2的最低体积分数晚上与白天几乎相当。O3体积分数的季节变化表现为夏季高,冬季低;与其相反,NO、NO2、NOx和CO几乎均表现为冬季高,夏季低。相对湿度、温度、风速与O3及其前体物的体积分数均具有显著的相关性。风速大于4.0m/s时,O3的平均体积分数仍然增大。

The continuous measurement of O3, NOx, CO and meteorological parameters at the ground layer was carried out from September 2004 to July 2005. The temporal variations and characteristics of concentration of ozone and its precursors, was analyzed. Then, the seasonal variations of ozone and its precursors, and the effects of local meteorological elements on O3, NOx and CO are studied by non-parametric statistics. The results show that, CO and NO2 were similar to the Lorentz distribution, and O3, NO and NOx were belonging to the exponential decay distribution. The diurnal variation in ozone accompanied with unimodal distribution shows a peak value around 15：00 at noon and a foot value around 7：00 in the morning, while the precursors accompanied with bimodal distribution show the first peak around 7：00 in the morning, the secondary one around 0：00 at daybreak, and a foot value around 15：00 at noon. The appearance of a first peak of NO2 is late to that of NO and CO. The lowest concentration of NO2 during late night is equal to that during daytime. The seasonal variation in ozone shows high concentration in summer and low concentration in winter; on the contrary, NO, NO2, NOx and CO show high concentrations in winter and low concentrations in summer. Relative humidity, temperature and wind speed have a significant correlation in ozone and its precursors. Mean concentration of ozone still increases while the wind speed is more than 4.0m/s.