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Trends of atmospheric CFCs and substitutes derived from 15 years of IASI measurements

par De Longueville, Hélène ;Clarisse, Lieven ;Franco, Bruno ;Whitburn, Simon ;Clerbaux, Cathy ;Coheur, Pierre
Référence Living Planet Symposium 2022 (23-27 May 2022: Bonn, Germany)
Publication Non publié, 2022-05-26

Poster de conférence

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Résumé :

The emissions of halocarbons have profoundly modified the chemical and radiative equilibrium of our atmosphere. These halogenated compounds are known to be powerful greenhouse gases and contribute, for chlorinated and brominated compounds, to the depletion of stratospheric ozone and to the development of the ozone hole. Their monitoring is therefore essential. The aim of this work is to assess the potential of infrared satellite sounders operating in the nadir geometry, to contribute to this monitoring and thereby to complement existing surface measurement networks. This work is centered on the exploitation of the measurements from the infrared satellite sounder IASI. The instrument stability and the consistency between the different instruments on the successive Metop platforms (A, B and C) is remarkable and makes it a reference for climate monitoring. Among other things, IASI offers the potential to investigate trends in the atmospheric abundance of various species better than with any other hyperspectral IR sounder. The low noise of the IASI radiances is also such that even weakly absorbing halocarbons can be identified. Recently, we managed to detect the spectral signatures of eight halocarbons: CFC-11, CFC-12, HCFC-22, HCFC-142b, HFC-134a, CF4, SF6 and CCl4. In this work we exploit the 15 years record of continuous IASI measurements to give a first assessment of the trend evolution of these species. This is done by targeting various geographical areas on the globe and examining the remote oceanic and continental source regions separately. The trend evolution in the different chemical species, either negative or positive, is validated against what is observed with ground-based measurement networks and other remote sensors. We conclude by assessing the usefulness of IASI and follow-on missions to contribute to the global monitoring of halocarbons.