北京2011年10月连续灰霾过程的特征与成因初探

Study on the Characteristics and Formation of a Multi-Day Haze in October 2011 in Beijing

选择2011年北京地区灰霾典型发生月——10月,利用在中国环境科学研究院监测的φ(SO2)、φ(O3)、φ(NO2)、φ(CO)、ρ(PM10)、ρ(PM2.5)、ρ(BC)等数据,对该地区秋季典型灰霾过程特征及成因进行了研究.在观测期间51.5%的时间内出现了灰霾,其中13.6%属于重度灰霾.对灰霾期间污染物时间分布特征的分析表明:在灰霾过程中ρ(PM1)、ρ(PM2.5)、ρ(PM10)及ρ(BC)较各自月均值的升幅均大于20%,ρ(PM1)ρ(PM2.5)(78.7%)也明显增大.大气能见度的降低与细颗粒物及亚微米颗粒物有直接关系.对观测期间的气象因素、气体污染物时间序列和颗粒物浓度累积特征的研究表明,10月连续灰霾过程的成因可能是该月频繁出现的鞍型场静稳天气及北京周边地区存在的基数较大的细颗粒物排放源所致.

The characteristics and formation of a multi-day haze episode that occurred in October 2011 in Beijing were studied based on analysis of the concentrations of the air pollutants SO2, 03, NO2, CO, PM10, PM2.5 and BC. During the observation period, haze occurred over 51.5% of the days, among which 13.6% were recognized as heavy haze episodes. During the haze, the coneentration of PM1 , PM25, PMI0 and BC were found to be increased by more than 20% , and the ratio of PMt over PM2.5 rose up to 78.7% . The relationship between PM mass concentration and visibility was analyzed, and the results showed that the appearance of haze was closely related to the mass concentration of fine and sub-micrometer PM. Study of the meteorological conditions, the time series of gaseous pollutants and the accumulation status of PM suggested that it was the frequently occurring cool pressure fields which promoted the formation of haze during the observation. Additionally, the huge amount of PM emissions in or around Beijing may be one of the major contributors of these episodes.