Spectroscopic database for TROPOMI/Sentinel-5P: CO and H2O at 2.3μm

Abstract

The TROPOspheric Monitoring Instrument (TROPOMI) aboard the European Space Agency's Copernicus Sentinel-5 Precursor satellite, to be launched this year, mandates high-accuracy spectral reference data for CO and H2O in the 2.3μm region [1]. We present measurements of absorption line parameters for H2O and for the 2-0 rovibrational band of CO to be used in TROPOMI atmospheric retrievals. The experiments were carried out on a Bruker IFS 125HR Fourier transform spectrometer and a multispectrum fitting software developed at DLR was used for parameter retrieval [2] using the Hartmann-Tran-Profile [3,4]. In the case of carbon monoxide, we report line intensities, air-broadening and -shift parameters for lines of the 2-0 rovibrational band, which serve as a useful validation of the HITRAN2012 spectral database [5] while our analysis of Dicke narrowing, speed dependence and Rosenkranz line mixing emphasizes the importance of modern line shape functions. Comparisons with previous studies of these non-Voigt parameters (e.g. [6]) show good agreement. As for H2O, spectral parameters were measured in the 4190cm-1-4340cm-1 spectral range. Comparisons of measured line intensities of the ν3 band show remarkable agreement (<1.5% deviation on average) with ab initio values [7,8] and we will present air-broadening, -narrowing and -shift parameters together with their temperature dependences. References [1] J.P. Veefkind et al, Remote Sensing of Environment 120, 70 (2012) [2] J. Loos et al, 13th HITRAN database conference, 2014 (doi: 10.5281/zenodo.11156) [3] N.H. Ngo et al, JQSRT 129, 89 (2013) [4] N.H. Ngo et al, JQSRT 134, 105 (2014) [5] L.S. Rothman et al, JQSRT 130, 4 (2013) [6] V.M. Devi et al, JQSRT 113, 1013 (2012) [7] L. Lodi et al, J Chem Phys 135, 034113 (2011) [8] J. Tennyson, University College London, Private communication