Optimization of spectral measurements of small atmospheric gases in the visible wavelength range
The paper considers the problem of optimizing daytime zenith integrated measurements of atmospheric gases over a certain wavelength range against the background of atmospheric aerosol, taking into account the known modification of the Angstrom formula given by King and Byrne. It has been taken into account that the coefficients available in this formula and characterizing the curvature of the characteristics of the dependence of the aerosol optical thickness on the wavelength depend on the time of day, the nature of the measurement zone (coast/continent; city /village), as well as the type of aerosol (fine, coarse). Considering the above, this article forms and solves the problem of optimizing multispectral measurements of small atmospheric gases throughout the day. During the specified time interval, the aerosol, characterized by high variability in time, introduces significant uncertainty in the results of the measurements. A method for optimizing multispectral daytime measurements of small atmospheric gases is proposed. Speaking of daytime measurements of the optical thickness of small atmospheric gases, we mean that such measurements can be carried out using a solar photometer or spectrometer. We assume that the results of the measurements carried out have a random multiplicative error due to the aerosol of the atmosphere. If some functional relationship exists between the selected measurement wavelength and the optical air mass, i.e. the measurement time during the day, measurement optimization has been determined to be achieved at the minimum value of the total optical thickness of the aerosol during the measurement period, which is equivalent to increasing reliability of the measurement results.