Document Type

Conference Paper

Publication Date

2014

Publication Title

Geophysical Research Abstracts

Volume

16

Pages

EGU2014-6873

Conference Name

European Geosciences Union, 12-17 April 2014, Vienna, Austria

Abstract

The majority of fluorine in the atmosphere has resulted from the anthropogenic emission of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Most tropospheric fluorine is present in its emitted 'organic' form due to the molecules having long lifetimes. At the top of the stratosphere most of the fluorine is present as the 'inorganic' product HF, which, due to its extreme stability, is an almost permanent reservoir of stratospheric fluorine. The second most abundant stratospheric 'inorganic' fluorine reservoir is carbonyl fluoride (COF₂). The major sources of COF₂ are from the atmospheric degradation of CFC-12 (CCl₂F₂), which is now banned under the Montreal Protocol, and HCFC-22 (CHF₂Cl), the most abundant HCFC and classed as a transitional substitute under the Montreal Protocol. Although the amount of CFC-12 in the atmosphere is slowly decreasing, HCFC-22 is still on the increase. The amounts of COF₂, HF, and total fluorine in the atmosphere are all still increasing.

Vertical profiles of COF₂ in the atmosphere have previously been determined from measurements taken by the Atmospheric Trace Molecule Spectrometry Experiment (ATMOS) instrument which flew four times on NASA space shuttles between 1985 and 1994. Additionally, there have been several studies into the seasonal variability of COF₂ columns above Jungfraujoch using ground-based Fourier transform infrared (FTIR) solar observations. The concentration of COF₂ in the atmosphere slowly increases with altitude up to the middle of the stratosphere, above which it decreases as photolysis becomes more efficient, leading to the production of HF.

The use of satellite remote-sensing techniques allows the measurement of COF₂ atmospheric abundances with impressive global coverage, and the investigation more fully of COF₂ trends, and seasonal and latitudinal variability. This work presents global distributions of COF₂ using data from two satellite limb instruments: the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS), onboard the SCISAT-1 satellite, which has been recording atmospheric spectra since 2004, and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument onboard the ENVIronmental SATellite (Envisat), which has recorded thermal emission atmospheric spectra between 2002 and 2012. The observations are compared with the output of SLIMCAT, a state-of-the-art three-dimensional chemical transport model (CTM). The model aids in the interpretation of the COF₂ satellite observations, and the comparison provides a validation of emission inventories and the atmospheric degradation reaction schemes used in the model.

Rights

© The Authors 2014

Published under the terms of a Creative Commons Attribution 3.0 Unported (CC BY 3.0) License.

Original Publication Citation

Harrison, J., Cai, S., Dudhia, A., Chipperfield, M., Boone, C., & Bernath, P. (2014). Retrievals of carbonyl fluoride (COF₂) from ACE-FTS and MIPAS spectra and their comparison with SLIMCAT CTM calculations. Geophysical Research Abstracts, 16, EGU2014-6873.

ORCID

0000-0002-1255-396X (Bernath)

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