Shipborne measurements of XCO 2 , XCH 4 , and XCO above the Pacific Ocean and comparison to CAMS atmospheric analyses and S5P/TROPOMI

[摘要] Measurements of atmospheric column-averaged dry-air mole fractions of carbon dioxide ( XCO 2 ), methane ( XCH 4 ), 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 shipborne variant of the EM27/SUN Fourier transform spectrometer (FTS) on board the German R/V  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 11000  cm −1 ). After filtering and bias correcting the dataset, we report on XCO 2 , XCH 4 , and XCO  measurements for 22 d 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 1 σ repeatability of hourly means of XCO 2 , XCH 4 , and XCO  is found to be 0.24  ppm , 1.1  ppb , and 0.75  ppb , respectively. The Copernicus Atmosphere Monitoring Service (CAMS) models gridded concentration fields of the atmospheric composition using assimilated satellite observations, which show excellent agreement of 0.52±0.31   ppm for XCO 2 , 0.9±4.1   ppb for XCH 4 , and 3.2±3.4   ppb for XCO  (mean difference ± SD, standard deviation, of differences for entire record) with our observations. 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 shipborne measurements are accessible at https://doi.org/10.1594/PANGAEA.917240 ( Knapp et al. ,  2020 ) .

[学科分类] 眼科学