Institute of Meteorology and Climate Research

MIPAS measures global CCl4 fields


Altitude-latitude cross-section of CCl4 in July 2008 as measured by MIPAS.

For the retrieval of CCl4 it is important to consider the interference of emissions of peroxyacetylnitrate (PAN), which is best accounted for by jointly fitting both these species. Further, line mixing in the Q-branch of CO2, which emits in the same spectral region, has to be considered. The use of new absorption cross-sections by J. Harrison has removed the high bias of the CCl4 retrieval. The decadal trend of MIPAS CCl4 data shows the hemispheric asymmetry also observed with numerous other MIPAS gases and supports the hypothesis of a shift of the subtropical mixing barriers as proposed by Stiller et al. (2017).
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