北京大气中常规污染物的垂直分布特征

近地层大气中的污染物的垂直变化对地面空气质量有直接影响.2004年9月22日─10月30日，以北京325 m气象塔为观测平台，分别在气象塔的8，47，120和280 m处，对大气中的O₃，CO，NO，SO₂和NO_x 5种污染物及温度、湿度、风向和风速4项气象要素进行同步连续观测.5种污染物在各层日变化均明显，其中8，47和120 m 3层的变化一致，但280 m处的φ(O₃)高于其下3层，夜间尤其明显.当φ(NO₂)/φ(NO)小于25时，φ(O₃)与该比值表现出很强的相关性，8，47，120和280 m处的相关系数分别为0.86，0.72，0.58和0.57.主成分分析中，280 m处各主成分组成与其下3层完全不同，进一步表明该处的污染物与低层污染物分布规律不同，该处的污染物除受局地湍流扩散影响外，还显著受到区域水平输送作用的影响. 

Characteristics of Vertical Air Pollutants in Beijing

The vertical variation of air pollutants has very close relation with near-surface air quality. Data on the concentrations of five atmospheric pollutants (O₃, CO, NO, SO₂ and NO_x) and four meteorological parameters (wind speed, wind direction, relative humidity and air temperature) were measured at 8, 47, 120, and 280　m respectively on the Beijing 325　m meteorological tower fromSeptember 22 to October 30, 2004. Distinct diurnal variations were observed forall the pollutants at 8, 47 and 120 m during the observed period, but the pollutants at 280 m have different variation characteristics. The concentration of O₃ at 280　m was much higher than that at other layers especially at night. The concentration of O₃ showed strong correlation with φ(NO₂)/φ(NO) ratio, when the φ(NO₂)/φ(NO) ratio was under 25. The correlation decreased gradually as the height increased from 0.86 to 0.57. Through principal component (PC) analysis, it was found that the composing of PCs and variances explained by each PC at 280 m was different from that atthe lower layers, which indicated that the advection transportation had important influence on the 280 m pollutants.