大气中的水汽对940nm附近的太阳辐射吸收较强，利用水汽吸收透过率与水汽量的关系可以反演大气柱水汽总量。介绍了基于太阳辐射计反演大气柱水汽总量的方法，并对合肥地区2005年至2006年间的晴空观测数据进行反演，结果表明合肥地区夏季水汽含量最高，冬季水汽含量最低，春夏季水汽含量高于秋冬季；在水汽含量高的7月和含量低的3月，大气垂程水汽总量在一天中的相对标准偏差分别为2．34%和6．27%，表明晴好天气时合肥地区的水汽量日变化不大。

There is water vapor absorption near 940 nm band, so the water vapor abundance can be retrieved on the basis of its functional dependence on the transmission in the 940 nm band. The method for determining water vapor abundance by using sunphotometers is described in detail. The clear-sky data of Hefei from 2005 to 2006 are analyzed. The results show that in Hefei the vertical water vapor abundance in spring and summer is higher than that in autumn and winter. In July and March its daily relative standard deviations are 2.34% and 6.27% respectively, so the water vapor abundance daily variation is small in clear days.