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© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

  27 Aug 2020

27 Aug 2020

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This preprint is currently under review for the journal ESSD.

Ship-borne measurements of XCO2, XCH4, and XCO above the Pacific Ocean and comparison to CAMS atmospheric analyses and S5P/TROPOMI

Marvin Knapp1, Ralph Kleinschek1, Frank Hase2, Anna Agustí-Panareda3, Antje Inness3, Jérôme Barré3, Jochen Landgraf4, Tobias Borsdorff4, Stefan Kinne5, and André Butz1,6 Marvin Knapp et al.
  • 1Institute of Environmental Physics, Heidelberg University, Germany
  • 2Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK-ASF), Karlsruhe, Germany
  • 3European Centre for Medium-Range Weather Forecasts, Shinfield Park, Reading, RG2 9AX, UK
  • 4Netherlands Institute for Space Research, SRON, Utrecht, the Netherlands
  • 5Max Planck Institute for Meteorology, Hamburg, Germany
  • 6Heidelberg Center for the Environment (HCE), Heidelberg University, Germany

Abstract. Measurements of atmospheric column-averaged dry-air mole fractions of carbon dioxide (XCO2), methane (XCH4), and carbon monoxide (XCO) have been collected across the Pacific ocean during the Measuring Ocean REferences 2 (MORE-2) campaign in June 2019. We deployed a ship-borne variant of the EM27/SUN Fourier Transform Spectrometer (FTS) on board the German research vessel Sonne which, during MORE-2, crossed the Pacific ocean from Vancouver, Canada, to Singapore. Equipped with a specially manufactured fast solar tracker, the FTS operated in direct-sun viewing geometry during the ship cruise reliably delivering solar absorption spectra in the shortwave infrared spectral range (4000 to 11 000 1/cm). After filtering and bias correcting the dataset, we report on XCO2, XCH4, and XCO measurements for 22 days along a trajectory that largely aligns with 30° N of latitude between 140° W and 120° E of longitude. The dataset has been scaled to the Total Carbon Column Observing Network (TCCON) station in Karlsruhe, Germany, before and after the MORE-2 campaign through side-by-side measurements. The precision for hourly means of XCO2, XCH4, and XCO during the campaign is found 0.24 ppm, 1.1 ppb, and 0.75 ppb, respectively. Comparing concentration fields analysed by the Copernicus Atmosphere Monitoring Service (CAMS) to our data, we find excellent agreement of 0.52 ± 0.31 ppm for XCO2, 0.9 ± 4.1 ppb for XCH4, and 3.2 ± 3.4 ppb for XCO (mean difference ± standard deviation of differences for entire record). Likewise, we find excellent agreement to within 2.2 ± 6.6 ppb with the XCO observations of the TROPOspheric MOnitoring Instrument (TROPOMI) on the Sentinel-5 Precursor satellite (S5P). The ship-borne measurements are accessible at (Knapp et al., 2020).

Marvin Knapp et al.

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Marvin Knapp et al.

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Column-averaged dry-air mole fractions of CO2, CH4, and CO from direct sunlight measurements above the Pacific during the MORE-2 campaign 2019 Marvin Knapp, Ralph Kleinschek, and André Butz

Marvin Knapp et al.


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Latest update: 21 Sep 2020
Short summary
We developed a ship-borne variant of a remote sensing spectrometer for direct sunlight measurements of column-averaged atmospheric mixing ratios of carbon dioxide, methane, and carbon monoxide. The instrument was deployed on the research vessel Sonne during a longitudinal transect over the Pacific during June 2019. The campaign yielded more than 32 000 observations which compare excellently to atmospheric composition data from a state of the art model (CAMS) and satellite observations (TROPOMI).
We developed a ship-borne variant of a remote sensing spectrometer for direct sunlight...