{"DOI":"10.5194/amt-5-1387-2012","abstract":"<p><strong>Abstract.</strong> The TROPOspheric Monitoring Instrument (TROPOMI) will be part of ESA's Sentinel-5 Precursor (S5P) satellite platform scheduled for launch in 2015. TROPOMI will monitor methane and carbon monoxide concentrations in the Earth's atmosphere by measuring spectra of back-scattered sunlight in the short-wave infrared (SWIR). <br><br> S5P will be the first satellite mission to rely uniquely on the spectral window at 4190\u20134340 cm<sup>\u22121</sup> (2.3 \u03bcm) to retrieve CH<sub>4</sub> and CO. In this study, we investigated if the absorption features of the three relevant molecules CH<sub>4</sub>, CO, and H<sub>2</sub>O are adequately known. To this end, we retrieved total columns of CH<sub>4</sub>, CO, and H<sub>2</sub>O from absorption spectra measured by two ground-based Fourier transform spectrometers that are part of the Total Carbon Column Observing Network (TCCON). The retrieval results from the 4190\u20134340 cm<sup>\u22121</sup> range at the TROPOMI resolution (0.45 cm<sup>\u22121</sup>) were then compared to the CH<sub>4</sub> results obtained from the 6000 cm<sup>\u22121</sup> region, and the CO results obtained from the 4190\u20134340 cm<sup>\u22121</sup> region at the higher TCCON resolution (0.02 cm<sup>\u22121</sup>). <br><br> For TROPOMI-like settings, we were able to reproduce the CH<sub>4</sub> columns to an accuracy of 0.3% apart from a constant bias of 1%. The CO retrieval accuracy was, through interference, systematically influenced by the shortcomings of the CH<sub>4</sub> and H<sub>2</sub>O spectroscopy. In contrast to CH<sub>4</sub>, the CO column error also varied significantly with atmospheric H<sub>2</sub>O content. Unaddressed, this would introduce seasonal and latitudinal biases to the CO columns retrieved from TROPOMI measurements. We therefore recommend further effort from the spectroscopic community to be directed at the H<sub>2</sub>O and CH<sub>4</sub> spectroscopy in the 4190\u20134340 cm<sup>\u22121</sup> region.</p>\n ","author":[{"family":"Galli"},{"family":"Butz"},{"family":"Scheepmaker"},{"family":"Hasekamp"},{"family":"Landgraf"},{"family":"Tol"},{"family":"Wunch"},{"family":"Deutscher"},{"family":"Toon"},{"family":"Wennberg"},{"family":"Griffith"},{"family":"Aben"}],"id":"unknown","issued":{"date-parts":[[2012,6,19]]},"language":"en","page-first":"1387","publisher":"Copernicus GmbH","title":"CH4, CO, and H2O spectroscopy for the Sentinel-5 Precursor mission: an assessment with the Total Carbon Column Observing Network measurements","type":"article-journal"}