Intercomparison of atmospheric CO 2 and CH 4 abundances on regional scales in boreal areas using Copernicus Atmosphere Monitoring Service (CAMS) analysis, COllaborative Carbon Column Observing Network (COCCON) spectrometers, and Sentinel-5 Precursor satellite observations

• Published in: Atmospheric Measurement Techniques
• Main Authors: Q. Tu, F. Hase, T. Blumenstock, R. Kivi, P. Heikkinen, M. K. Sha, U. Raffalski, J. Landgraf, A. Lorente, T. Borsdorff, H. Chen, F. Dietrich, J. Chen
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2020
• Subjects: Environmental engineering; TA170-171; Earthwork. Foundations; TA715-787; Kiruna; Sodankylä
• Online Access: https://doi.org/10.5194/amt-13-4751-2020; https://doaj.org/article/d0a98d46ccfc4f868ace603ed3c58685

We compare the atmospheric column-averaged dry-air mole fractions of carbon dioxide ( XCO 2 ) and methane ( XCH 4 ) measured with a pair of COllaborative Carbon Column Observing Network (COCCON) spectrometers at Kiruna and Sodankylä (boreal areas). We compare model data provided by the Copernicus Atmosphere Monitoring Service (CAMS) between 2017 and 2019 with XCH 4 data from the recently launched Sentinel-5 Precursor (S5P) satellite between 2018 and 2019. In addition, measured and modeled gradients of XCO 2 and XCH 4 ( Δ XCO 2 and Δ XCH 4 ) on regional scales are investigated. Both sites show a similar and very good correlation between COCCON retrievals and the modeled CAMS XCO 2 data, while CAMS data are biased high with respect to COCCON by 3.72 ppm ( ±1.80 ppm) in Kiruna and 3.46 ppm ( ±1.73 ppm) in Sodankylä on average. For XCH 4 , CAMS values are higher than the COCCON observations by 0.33 ppb ( ±11.93 ppb) in Kiruna and 7.39 ppb ( ±10.92 ppb) in Sodankylä. In contrast, the S5P satellite generally measures lower atmospheric XCH 4 than the COCCON spectrometers, with a mean difference of 9.69 ppb ( ±20.51 ppb) in Kiruna and 3.36 ppb ( ±17.05 ppb) in Sodankylä. We compare the gradients of XCO 2 and XCH 4 ( Δ XCO 2 and Δ XCH 4 ) between Kiruna and Sodankylä derived from CAMS analysis and COCCON and S5P measurements to study the capability of detecting sources and sinks on regional scales. The correlations in Δ XCO 2 and Δ XCH 4 between the different datasets are generally smaller than the correlations in XCO 2 and XCH 4 between the datasets at either site. The Δ XCO 2 values predicted by CAMS are generally higher than those observed with COCCON with a slope of 0.51. The Δ XCH 4 values predicted by CAMS are mostly higher than those observed with COCCON with a slope of 0.65, covering a larger dataset than the comparison between S5P and COCCON. When comparing CAMS Δ XCH 4 with COCCON Δ XCH 4 only in S5P overpass days (slope = 0.53), the correlation is close to that between S5P and COCCON (slope = 0.51). CAMS, ...