Comparison between the Spectra of Outgoing Infrared Radiation for Different Years

—Comparisons of outgoing IR radiation spectra measured bу Fourier SI-1 spectrometer in 1977 and 1979 from the Meteor-28 and -29 satellites to numerical calculations on the basis of the modern LBLRTM code and data of atmospheric radio sounding are carried out. In most cases, mean differences between measurements and calculations do not exceed 2 mW/(m 2 sr cm –1 ) in the 660–1600 cm –1 spectral range. Standard deviations and mean square differences are, on average, 2–4 mW/(m 2 sr cm –1 ). These values are greater bу about 1 mW/(m 2 sr cm –1 ) than relevant differences between calculations and measurements for modern IKFS-2 spectrometer. Comparisons of experimental spectra of 1977, 1979 and 2015–2016 have shown that, on average, the intensity of outgoing IR radiation measured bу the IKFS-2 device, is bу 0.5–3.0 mW/(m 2 sr cm –1 ) less than SI-1 radiation measurements onboard Meteor-28 and -29 satellites obtained 40 years ago. This effect may be associated with the СО 2 increase in the atmosphere and the resulting raising of radiating atmosphere layers to tropospheric layers with а smaller temperature.