EXTREME METHOD FOR SOLAR PHOTOMETERS CALIBRATION

Abstract

Solar photometers are currently one of the main meteorological instruments with which the optical thickness of atmospheric aerosol and the total amount of water vapor in the atmosphere can be measured. These devices are also functionally suitable for estimating the total amount of ozone in the atmosphere, which confirms the importance of solar photometers for meteorological science. At present, aerosol measurement networks based on such devices are being built everywhere. The most important condition for the normal functioning of a solar photometer is the accurate calibration of this device. The article is devoted to the development of a new method of calibration of solar photometers, in which the influence of atmospheric aerosol instability is almost completely eliminated. It is shown that the total calibration error of solar photometers consists of two components: (a) the error caused by the instability of atmospheric aerosol; (b) the error of the geometric construction of the Langley diagram. The first of these components is practically considered unrecoverable by existing methods, and the second can be eliminated using previously proposed computational methods. The developed extreme method of calibration of solar photometers eliminates the need to construct a Langley diagram for several hours, during which the atmospheric aerosol, due to its variability, introduces a significant error in the calibration result. Thus, the main drawback of the classical Langley method is eliminated. The effect of increasing the accuracy of calibration is achieved by forming an additional informative indicator and further investigation of the extremum of this newly introduced indicator. Quantitative indicators of the achieved effect of increasing accuracy are given. As an example, it is shown that despite some high duration of implementation of the proposed method, it becomes possible to eliminate the aerosol error of 2.74 % that occurs when the optical thickness of the atmosphere is less than 0.1, and when this indicator is unstable by 10 percent during the implementation of the Langley method. The functional optical scheme of the device and the algorithm for implementing the proposed calibration method are given.