SELF BROADENING COEFFICIENTS AND IMPROVED LINE INTENSITIES FOR THE v7 BAND OF C2H4 NEAR 10.5 µm, AND IMPACT ON ETHYLENE RETRIEVALS FROM JUNGFRAUJOCH SOLAR SPECTRA

Relying on high-resolution Fourier transform infrared (FTIR) spectra, the present work
involved extensive measurements of individual line intensities and self-broadening
coefficients for the ν7 band of 12C2H4. The measured self-broadening coefficients exhibit
a dependence on both J and Ka. Compared to the corresponding information available in
the latest edition of the HITRAN spectroscopic database, the measured line intensities
were found to be higher by about 10 % for high J lines in the P branch and lower by about
5 % for high J lines of the R branch, varying between these two limits roughly linearly with
the line positions. The impact of the presently measured line intensities on retrievals of
atmospheric ethylene in the 949.0–952.0cm 1 microwindow was evaluated using a
subset of ground-based high-resolution FTIR solar spectra recorded at the Jungfraujoch
station. The use of HITRAN 2012 with line intensities modified to match the present
measurements led to a systematic reduction of the measured total columns of ethylene by
-4.1 +/- 0.1 %.