Abstract
Abstract. The column-averaged dry-air mole fractions of CO2 (XCO2), CH4 (XCH4) and CO (XCO) have been measured with a Bruker IFS 125HR Fourier-transform infrared (FTIR) spectrometer at Xianghe (39.75∘ N, 116.96∘ E, north China) since June 2018. This paper presents the site, the characteristics of the FTIR system and the measurements. The instrumental setup follows the guidelines of the Total Carbon Column Observing Network (TCCON): the near-infrared spectra are recorded by an InGaAs detector together with a CaF2 beam splitter, and the HCl cell measurements are recorded regularly to derive the instrument line shape (ILS) showing that the instrument is correctly aligned. The TCCON standard retrieval code (GGG2014) is applied to retrieve XCO2, XCH4 and XCO. The resulting time series between June 2018 and July 2019 are presented, and the observed seasonal cycles and day-to-day variations in XCO2, XCH4 and XCO at Xianghe are discussed. In addition, the paper shows comparisons between the data products retrieved from the FTIR measurements at Xianghe and co-located Orbiting Carbon Observatory-2 (OCO-2) and Tropospheric Monitoring Instrument (TROPOMI) satellite observations. The comparison results appear consistent with validation results obtained at TCCON sites for XCO2 and XCH4, while for XCO they highlight the occurrence of frequent high-pollution events. As Xianghe lies in a polluted area in north China where there are currently no TCCON sites, this site can fill the TCCON gap in this region and expand the global coverage of the TCCON measurements. The Xianghe FTIR XCO2, XCH4 and XCO data can be obtained at https://doi.org/10.18758/71021049 (Yang et al., 2019).
Highlights
The rapid economic growth of China has contributed to 28.5 % of the global total carbon dioxide (CO2) emissions from fossil fuel consumption and cement production (Jackson et al, 2017)
The absolute differences between Orbiting Carbon Observatory-2 (OCO-2) v9 lite data and Xianghe FTIR data are comparable with the results found for the v7 lite products in Wunch et al (2017) for other Total Carbon Column Observing Network (TCCON) stations with biases ranging from −0.7 ± 1.32 ppm (Wollongong) to 0.9 ± 1.49 ppm (Karlsruhe) in land glint mode and ranging from −0.1 ± 1.04 ppm (Wollongong) to 1.6 ± 2.05 ppm (Garmisch) in nadir mode
A new ground-based FTIR Bruker 125HR instrument has been in operation since 14 June 2018 at Xianghe (39.75◦ N, 116.96◦ E) in north China
Summary
The rapid economic growth of China has contributed to 28.5 % of the global total carbon dioxide (CO2) emissions from fossil fuel consumption and cement production (Jackson et al, 2017). The Total Carbon Column Observing Network (TCCON) uses ground-based FTIR spectrometers to measure the direct solar radiation in the near-infrared spectral region, from which the total column-averaged dry-air mole fractions of CO2, CH4, N2O, CO, hydrogen fluoride (HF), H2O and semi-heavy water (HDO) are retrieved (Wunch et al, 2011b). Because of their relatively high precision and accuracy, TCCON data are widely used in satellite validations and model comparisons (Zhou et al, 2016; Ostler et al, 2016; Crisp et al, 2017; Borsdorff et al, 2018; Velazco et al, 2019).
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