中文摘要：

针对2012年珠江三角洲地区出现的2个典型灰霾个例（3月18-21日，10月13∽15日），利用广州番禺大气成分综合观测基地的同期观测资料集，包括：能见度（VIS）、大气颗粒物质量浓度（PM10／PM2.5／PM1）、黑碳浓度（BC）等观测数据，分析过程中的气溶胶物理光学特征；配合过程的天气类型，气象要素和后向气流轨迹等对过程的成因进行综合分析．结果表明：在两个典型灰霾过程中，番禺日均能见度低至5．3km，黑碳浓度小时均值最高达19．0μg／m3 PM25浓度小时均值最高达163．0μg／m3,细粒子与黑碳粒子污染特征较为明显．两次典型灰霾过程分别受到冷锋前-均压场-冷锋前天气形势和台风外围-准均压场-冷锋前天气类型等不利于污染物输送扩散的气象条件影响．珠江三角洲地区低能见度的霾天气主要发生在高相对湿度的条件下，并可推断在珠江三角洲地区湿季的气溶胶吸湿能力明显高于干季．

英文摘要：

Two typical hazy weather events which occurred in the Pearl River Delta （PRD） cities from Mar. 18 to Mar. 21 and from Oct. 13 to Oct. 15, 2012respectively were selected in this paper. A comprehensive analysis of the causes of the events was made by using the in situ measurement of visibility （VIS）, aerosol mass concentration （PMI0/PM2.5/PM1）, the concentration of black carbon （BC） at an integrated observation base for atmospheric composition in Panyu, Guangzhou, the weather type, meteorological elements and backward airflow trajectory during these events. The results are shown as follows： Daily visibility was as low as 5.3km, black carbon＇s hourly concentration value was up to 19.0μg/m3, PM2.s＇s hourly concentration was 163.0μg/m3at its highest. These two events were affected by the weather conditions which weren＇t conducive to the transport or spread of pollutants. In PRD, low visibility of haze weather occurs mainly in condition of high relative humidity. It is deduced that aerosol has greater hygroscopicity in the dry season than in the wet season in this region.