利用常规观测的总辐射和散射辐射日曝辐量资料,结合NASAGISS的月平均平流层气溶胶光学厚度(AOD)产品,反演计算了北京等12个台站1961~2005年0.75μm对流层AOD和气溶胶标高数据.基于这些数据,分析了各站AOD、气溶胶标高和地面能见度的年、季、月变化特征.结果表明:①就12个站45a总平均而言,光学厚度为0.276,年增长为0.0034;气溶胶标高为1.65km,年增加为0.015km;能见度为17.1km,年变化值为-0.08km;AOD春夏较大,秋冬较小;气溶胶标高夏季最高,春季次之,冬季最低.②各站点45a平均AOD范围为0.116—0.387;除格尔木外,各站AOD均有增长,年变化值为0.0010~0.0079.③20世纪70、80年代AOD增加明显;20世纪90年代以来,多数站点AOD有所下降,能见度有转好趋势.
The tropospheric aerosol optical depths (AOD) at 0.75μm were retrieved by a new method using the daily global and diffuse insolations and the NASA GISS monthly mean stratospheric AOD data at 12 meteorological stations in China from 1961 to 2005. Analyses on the characteristics of AOD, aerosol scaling height (ASH) and surface visibility were made based on the monthly mean tropospheric AODs. It was found that the yearly mean AODs showed an increasing trend at most stations during the last 45 years. The mean values of AOD, ASH and visibility from all stations were O. 276, 1.65 km and 17.1 km, respectively and their annual increments were 0. 0034·a^-1, 0.015km·a^-1 and - 0.08km·a^-1, respectively. AOD in spring and summer was greater than that in autumn and winter. The highest ASH appeared in summer, while the lowest in winter. For individual stations, the mean AOD over all 45 years ranged from O. 116 to O. 387. Iucreasing trends of AOD were observed at all stations except Geermu, with annual increments ranging from 0.0010 to 0.0079. AOD reached the highest level in most stations during the 1980s, with an average increment of O. 101 relative to that of the 1960s. Since 1990, a slight decreasing trend was found in AOD. along with an increase in visibility.