Compensation for the systematic error of spectral measurements of the methane background in the Earth's atmosphere

Abstract

The article considers the errors of the passive location method when measuring the background concentration of methane in the atmosphere using the Sun as a radiation source in the area of the northeast of the Moscow region. In the course of processing the measurement results, it was found that, along with random errors, it is necessary to take into account the systematic error due to the infl uence of extraneous factors on the measurements of the methane background concentration when sounding at small angles to the horizon, when the path length noticeably increases. A possible infl uence on the magnitude of the systematic error is the scattering of light by aerosols and other impurity particles present in the Earth's atmosphere. After the introduction of compensation corrections, the systematic error was reduced to values close to zero. The proposed method for monitoring the background of methane makes it possible to carry out measurements over long periods of time with a relative accuracy of a few percent. The results of the measurements are consistent with the results of global measurements and confi rm the trend of increasing the background concentration of methane in the Earth's atmosphere in recent years.