Determining Both Tropospheric and Stratospheric СО2 Contents Using a Ground-Based IR Spectroscopic Method

Results obtained from ground-based high spectral resolution measurements of solar IR radiation absorption spectra are analyzed. These measurements have been carried out in Peterhof for different ranges of electromagnetic waves to determine the atmospheric total content of СО2 and its contents in the two atmospheric layers—the troposphere and stratosphere. Two spectral schemes to measure solar spectra within ranges of 2600 and 3100–3300 cm–1 are chosen based on an analysis of errors in measurements using different spectral schemes and comparisons with independent measurements and simulation data. Time variations in the tropospheric and stratospheric contents of СО2 for the 2018–2019 period are studied. Within this period, the ХСО2 values in the troposphere mostly exceed those in the stratosphere, and such an excess reached 5–10 ppm. The reverse situation is observed in summer and early fall, when the ХСО2 values in the stratosphere exceed those in the troposphere, which is associated with photosynthesis processes (absorption of СО2 by vegetation in the troposphere). Comparisons of ground-based measurement results with CAMS simulation data and satellite OCO-2 and ACE data show a good agreement for the total content of СО2 and its tropospheric and stratospheric contents. The errors are within 1% if systematic discrepancies are excluded.