半干旱区冬春季黑碳气溶胶吸收特性的观测研究

Observational Study on Aerosol Absorption Properties in Winter and Spring in Semiarid Area

利用2006年4月和12月锡林浩特观象台黑碳灰度仪的观测资料,分析了半干旱地区黑碳气溶胶浓度的变化特征,讨论了引起这些变化特征的影响因子。结果表明,黑碳气溶胶浓度冬季远大于春季,日变化呈明显的双峰型;讨论了风速对黑碳气溶胶浓度不同影响的范围,可知风速在较小的情况下（小于3.5 m·s^-1）,黑碳气溶胶浓度值随风速的增大而减小;在3.5～4.5 m·s^-1之间,风速增大,黑碳气溶胶浓度值也增大;风速较大（大于4.5 m·s^-1）后,黑碳气溶胶浓度与风速之间没有明显的相关性。冬季12月由于黑碳气溶胶吸收作用造成的消光占总气溶胶消光的25%。

The aerosol absorption properties were measured with an aethalometer in April and December 2006. Analyzing these real-time black carbon （BC） mass concentration data, we found that the BC mass concentration in winter was much larger than in spring, the daily variations of concentration in the two seasons present a curve of bi-peaks. We specially analyzed the wind speed range which has different influence on BC concentration, and found that when the wind speed is slow（less than 3.5 m·s^-1）, there has an significantly dilution effect to BC concentration. When the wind speed is between 3.5-4.5 m·s^-1, the BC concentration increases as the wind speed increased. When the wind speed is larger than 4.5 m·s^-1, no apparent relevance is occurred. We also discussed the relationship between the absorption coefficient and the visibility, and we found that the extinction due to aerosol absorption is 25 % of the total extinction which due to aerosol absorption and scattering in winter.