SUN-PHOTOMETER CALIBRATION AND ITS APPLICATION

Sun-photometer has been widely used to investigate various optical properties of the atmosphere.In order to derive an accurate atmospheric optical depth,great care in the sun-photometer calibration is required.In this paper,the feature of a new sun-photometer is described.Calibration results based on the Langley method at Mt.Huangshan are reported.Effect of the atmospheric instability on retrieving the calibration values is discussed and errors in calibration at Mt.Huangshan due to temporal variation of aerosol concentration are estimated.It is shown that the calibrated sun-photometer can be used to derive the atmospheric optical depth to an accuracy of 5%.As one of its applications,examples of determination of turbidity parameters and columnar aerosol size distribution are presented.