中文摘要：

黑碳气溶胶（BC）是大气气溶胶中的重要成分,在可见光和红外光都具有强烈吸收作用,对局地和全球气候有重要的影响。利用兰州大学半干旱气候环境观测站（SACOL）历时近一年的观测资料结合常规气象资料对我国半干旱地区的BC浓度特征进行研究。结果表明,该地区全年平均BC浓度为1797.3ng·m-3,低于我国城市地区;测站BC浓度日变化趋势呈双峰特征,日最高浓度多出现在第一个波峰,第二个波峰的浓度值较小且峰型不如前者明显;降水可以有效地清除大气中16%～40%的BC。

英文摘要：

Black carbon （BC） is a very important component of the aerosols. It contributes significantly to the regional and global climate changes,due to its strong absorption in the visible and infrared range. The used data are observed during April 2007 to March 2008 at the Semi-Arid Climate and Environment Observatory of Lanzhou University （SACOL）,Gansu Province. The variation characteristics of the BC concentrations are discussed combined with the meteorological observational data. The means concentration of BC at SACOL is 1797.3 ng·m-3,which is lower than that in the cities.The variation of BC concentration is controlled by the diurnal and seasonal variations of the local circulation and local anthropogenic activity. The hourly means of the BC concentrations show a diurnal variation characterized by a pronounced double-peak pattern with the high values in the morning and the evening,and the concentration is getting higher and higher in winter. Precipitation is an effective way of cleaning BC.