Spectroscopic measurements of the total methane content in the atmosphere near St Petersburg

Results of determination of the daily mean values of the total methane content (omega(CH4)) from the spectra of the direct solar radiation, measured in the LR spectral range during 1991-1993, are presented. The seasonal variations of omega(CH4) are revealed. The variations are characterized by a well. pronounced maximum in the fall-spring period and by a minimum in summer, and by the amplitude oi about 10% of the averaged for all the period of measurements value of omega(CH4) = 1.39 atm cm. Based on the interpretation results of the measured spectra it is suggested that in the point of spectral measurements there may exist an inhomogeneity of the methane vertical distribution due to an influence of industrial objects. Comparison of the obtained results with the results of similar measurements during the same period of time in Zvenigorod and Obninsk demonstrate a significant disagreement of the methane total content variations in all three points of measurements.