香格里拉区域大气本底站地面臭氧浓度的变化特征

对2009年香格里拉区域大气本底站地面臭氧观测结果进行分析,研究其浓度水平、变化特征、影响因素及其区域代表性。结果表明:香格里拉站地面O₃月均值浓度在21.8~57.7 ppb,年平均值为38.0±12.1 ppb,在春季最高,平均值为54.1 ppb,在夏季最低,平均值为28.0 ppb。O₃小时均值浓度超过60 ppb的小时数占总有效小时数的6.6%,超过40 ppb的小时数占43.0%。与相近纬度中国东部地区区域大气本底站地面臭氧观测结果相比,香格里拉站体现出不同的O₃日变化和季节变化特征,具有特殊的地域特征。影响香格里拉站的气流主要来自于其西南方向,3 d的后向轨迹可追溯到孟加拉湾东北部地区。偏南的气流主要出现在夏秋季节,O₃浓度相对低,偏北的气流以冬春为主,O₃浓度相对高。

CHARACTERISTICS OF THE SURFACE OZONE AT SHANGRI-LA REGIONAL ATMOSPHERIC BACKGROUND STATION

The observation results of the surface ozone (O₃) at Shangri-la regional atmospheric background station in 2009 were studied and the concentration level, the seasonal and diurnal variation, the affecting factors and the regional representativeness were presented. The monthly O₃ at the station varied from 21.8 ppb to 57.7 ppb. The yearly average value was 38.0±12.1 ppb, with a peak value in spring (54.1 ppb) and a valley value in summer (28.0 ppb). The hours with the hourly concentration larger than 60 ppb and larger than 40 ppb accounted for 6.6% and 43.0% of the total observation hours, respectively. When compared with the observation results at the two regional atmospheric background stations with a similar latitude located in the eastern China, it showed a different diurnal and seasonal variation pattern of O₃ at Shangri-la station, reflecting a unique ecosystem and environmental conditions surrounded. The airflow influencing the station is mainly from the southwest direction, which can be from as far as the northeast area in Bay of Bengal under a 3-days moving trajectory. The airflow coming from the south mainly occurred in summer-autumn period with a relatively lower ozone concentration and the airflow coming from the north mainly occurred in winter-spring period with a relatively higher ozone values.