IMG evidence of chlorofluorocarbon absorption in the atmospheric window region 800–900 cm−1

Abstract

Infrared spectra recorded by the interferometric monitoring of greenhouse gases sensor have been analysed to assess the effect of the molecule CCl3F in the atmospheric window region 800–900cm−1. The analysis has been carried out at a sampling rate of 0.25cm−1 which is typical of next generation space borne infrared sensors such as the European infrared atmospheric sounding interferometer. It has been found that at this spectral resolution absorption by CCl3F is clearly evident and mostly effective in the spectral range 840–860cm−1 where it may account for up to 1K depletion in the brightness temperature spectrum. It will be shown that a CCl3F concentration of 270pptv (mixing ratio) fits very well to the spectral observations. Our findings show that chlorofluorocarbons may play an interfering role in determining surface or close to surface geophysical parameters. On the other hand, the fact that these compounds are clearly identifiable in infrared spectra opens the way to an effective monitoring of their presence and abundance from space.