Infrared absorption cross sections for methanol

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Infrared absorption cross sections for methanol, CH3OH, have been determined near 3.4 and 10μm from spectra recorded using a high-resolution FTIR spectrometer (Bruker IFS 125HR) and a multipass cell with a maximum optical path length of 19.3m. Methanol/dry synthetic air mixtures were prepared and spectra were recorded at 0.015cm−1 resolution (calculated as 0.9/MOPD) at a number of temperatures and pressures (50–760Torr and 204–296K) appropriate for atmospheric conditions. Intensities were calibrated using composite methanol spectra taken from the Pacific Northwest National Laboratory (PNNL) IR database. The new measurements in the 10μm region indicate problems with the existing methanol spectroscopic line parameters in the HITRAN database, which will impact the accuracy of satellite retrievals.