The NDACC data used in this publication were obtained as part of the Network for the Detection of Atmospheric Composition Change (NDACC) and are publicly available (see http://www.ndaccdemo.org/, last access: 1 June 2021). Rapid delivery data on NDACC are supported for selected sites by the CAMS27 project (https://cams27.aeronomie.be/, last access: 1 June 2021). The National Center for Atmospheric Research is sponsored by the National Science Foundation. The NCAR FTS observation programmes at Thule, GR, Boulder, CO, and Mauna Loa, HI, are supported under contract by the National Aeronautics and Space Administration (NASA). The Thule work is also supported by the NSF Office of Polar Programs (OPP). We wish to thank the Danish Meteorological Institute for support at the Thule site and NOAA for support of the Mauna Loa Observatory (MLO) site. The NDACC and TCCON stations (Ascension Island, Bremen, Garmisch, Izaña, Ny-Ålesund, Paramaribo and Karlsruhe) have been supported by the German Bundesministerium für Wirtschaft und Energie (BMWi) via DLR under grants 50EE1711A-E. The FTIR sites (Garmisch, Izaña, Karlsruhe, Kiruna and Zugspitze) have been supported by the Helmholtz Society via the research program ATMO. The NDACC/TCCON Izaña data benefit from the financial support from the Ministerio de Economía y Competitividad from Spain for the project INMENSE (CGL2016-80688-P). We thank the International Foundation High Altitude Research Stations Jungfraujoch and Gornergrat (HFSJG, Bern) for supporting the facilities needed to perform the FTIR observations at Jungfraujoch. The University of Liège contribution has been supported primarily by the Fonds de la Recherche Scientifique - FNRS under grant no. J.0147.18, by the GAW-CH program of MeteoSwiss, as well as by the CAMS project. Emmanuel Mahieu is a senior research associate of the F.R.S.-FNRS. The RUOA network "Red Universitaria de Observatorios Atmosféricos de la Universidad Nacional Autónoma de México" is acknowledged for the support of the Altzomoni site. Omar Lopez and Delibes Flores Roman are acknowledged for technical support. Alejandro Bezanilla and Noemie Taquet are acknowledged for helping with measurements and data processing. For the Altzomoni site, UNAM-DGAPA (grant nos. IN111418 and IN107417) and CONACYT (grant no. 290589) are acknowledged. The St. Petersburg State University with the financial support provided by the Russian Foundation for Basic Research (grant no. 18-05-00011). The scientific equipment is maintained by the Geomodel research centre of SPbU. The NDACC site at Rikubetsu is operated as parts of the joint research programme of the Institute for Space-Earth Environmental Research (ISEE), Nagoya University, and supported in part by the GOSAT series project. The Wollongong NDACC site is funded by the Australia Research Council (grant no. DP160101598). Measurements at Lauder and Arrival Heights are core funded by NIWA through New Zealand's Ministry of Business, Innovation and Employment Strategic Science Investment Fund. Dan Smale thanks Antarctica New Zealand for providing support for the measurements at Arrival Heights.

**Financial support.** This research has been supported by the European Space Agency (ESA/ESRIN, contract no. 4000117151/16/ILG) and the Belgian Federal Science Policy Office (BELSPO), the Royal Belgian Institute for Space Aeronomy (BIRA-IASB), the S5P Validation Team (S5PVT) AO project TCCON4S5P (ID

no. 28603, PI Mahesh Kumar Sha, BIRA-IASB) with national funding from the BELSPO through the ESA ProDEX projects TROVA and TROVA-E2 (PEA 4000116692).

**Review statement.** This paper was edited by Andreas Richter and reviewed by two anonymous referees.

## References

Bader, W., Bovy, B., Conway, S., Strong, K., Smale, D., Turner, A. J., Blumenstock, T., Boone, C., Collaud Coen, M., Coulon, A., Garcia, O., Griffith, D. W. T., Hase, F., Hausmann, P., Jones, N., Krummel, P., Murata, I., Morino, I., Nakajima, H., O'Doherty, S., Paton-Walsh, C., Robinson, J., Sandrin, R., Schneider, M., Servais, C., Sussmann, R., and Mahieu, E.: The recent increase of atmospheric methane from 10 years of ground-based NDACC FTIR observations since 2005, Atmos. Chem. Phys., 17, 2255–2277, https://doi.org/10.5194/acp-17-2255-2017, 2017.

Batchelor, R. L., Strong, K., Lindenmaier, R., Mittermeier, R. L., Fast, H., Drummond, J. R., and Fogal, P. F.: A New Bruker IFS 125HR FTIR Spectrometer for the Polar Environment Atmospheric Research Laboratory at Eureka, Nunavut, Canada: Measurements and Comparison with the Existing Bomem DA8 Spectrometer, J. Atmos. Ocean. Tech., 26, 1328–1340, https://doi.org/10.1175/2009JTECHA1215.1, 2009.

Baylon, J. L., Stremme, W., Grutter, M., Hase, F., and Blumenstock, T.: Background CO₂ levels and error analysis from ground-based solar absorption IR measurements in central Mexico, Atmos. Meas. Tech., 10, 2425–2434, https://doi.org/10.5194/amt-10-2425-2017, 2017.

Bergamaschi, P., Frankenberg, C., Meirink, J. F., Krol, M., Dentener, F., Wagner, T., Platt, U., Kaplan, J. O., Körner, S., Heimann, M., Dlugokencky, E. J., and Goede, A.: Satellite chartography of atmospheric methane from SCIAMACHY on board ENVISAT: 2. Evaluation based on inverse model simulations, J. Geophys. Res., 112, D02304, https://doi.org/10.1029/2006JD007268, 2007.

Bezanilla, A., Krüger, A., Stremme, W., and de la Mora, M. G.: Solar absorption infrared spectroscopic measurements over Mexico City: Methane enhancements, Atmósfera, 27, 173–183, 2014.

Blumenstock, T., Hase, F., Schneider, M., García, O. E., and Sepúlveda, E.: TCCON data from Izana (ES), Release GGG2014.R1, Version R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.IZANA01.R1, 2017.

Borsdorff, T., Tol, P., Williams, J. E., de Laat, J., aan de Brugh, J., Nédélec, P., Aben, I., and Landgraf, J.: Carbon monoxide total columns from SCIAMACHY 2.3 µm atmospheric reflectance measurements: towards a full-mission data product (2003–2012), Atmos. Meas. Tech., 9, 227–248, https://doi.org/10.5194/amt-9-227-2016, 2016.

Borsdorff, T., aan de Brugh, J., Hu, H., Hasekamp, O., Sussmann, R., Rettinger, M., Hase, F., Gross, J., Schneider, M., Garcia, O., Stremme, W., Grutter, M., Feist, D. G., Arnold, S. G., De Mazière, M., Kumar Sha, M., Pollard, D. F., Kiel, M., Roehl, C., Wennberg, P. O., Toon, G. C., and Landgraf, J.: Mapping carbon monoxide pollution from space down to city scales with
daily global coverage, Atmos. Meas. Tech., 11, 5507–5518, https://doi.org/10.5194/amt-11-5507-2018, 2018a.

Borsdorff, T., Aan de Brugh, J., Hu, H., Aben, I., Hasekamp, O., and Landgraf, J.: Measuring Carbon Monoxide With TROPOMI: First Results and a Comparison With ECMWF-IFS Analysis Data, Geophys. Res. Lett., 45, 2826–2832, https://doi.org/10.1002/2018GL077045, 2018b.

Borsdorff, T., aan de Brugh, J., Schneider, A., Lorente, A., Birk, M., Wagner, G., Kivi, R., Hase, F., Feist, D. G., Sussmann, R., Rettinger, M., Wunch, D., Warneke, T., and Landgraf, J.: Improving the TROPOMI CO data product: update of the spectroscopic database and destriping of single orbits, Atmos. Meas. Tech., 12, 5443–5455, https://doi.org/10.5194/amt-12-5443-2019, 2019.

Borsdorff, T., García Reynoso, A., Maldonado, G., Mar-Morales, B., Stremme, W., Grutter, M., and Landgraf, J.: Monitoring CO emissions of the metropolis Mexico City using TROPOMI CO observations, Atmos. Chem. Phys., 20, 15761–15774, https://doi.org/10.5194/acp-20-15761-2020, 2020.

Buchholz, R. R., Deeter, M. N., Worden, H. M., Gille, J., Edwards, D. P., Hannigan, J. W., Jones, N. B., Paton-Walsh, C., Griffith, D. W. T., Smale, D., Robinson, J., Strong, K., Conway, S., Sussmann, R., Hase, F., Blumenstock, T., Mahieu, E., and Langerock, B.: Validation of MOPITT carbon monoxide using ground-based Fourier transform infrared spectrometer data from NDACC, Atmos. Meas. Tech., 10, 1927–1956, https://doi.org/10.5194/amt-10-1927-2017, 2017.

Copernicus Sentinel-5P: TROPOMI Level 2 Carbon Monoxide total column products, Version 01, ESA (European Space Agency) [data set], https://doi.org/10.5270/S5P-1hkp7rp, 2018.

Copernicus Sentinel-5P: TROPOMI Level 2 Methane Total Column products, Version 01, ESA (European Space Agency) [data set], https://doi.org/10.5270/S5P-3p6lnwd, 2019.

De Mazière, M., Sha, M. K., Desmet, F., Hermans, C., Scolas, F., Kumps, N., Metzger, J.-M., Duflot, V., and Cammas, J.-P.: TCCON data from Réunion Island (RE), Release GGG2014.R1, Version R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.REUNION01.R1, 2017.

Deutscher, N. M., Griffith, D. W. T., Bryant, G. W., Wennberg, P. O., Toon, G. C., Washenfelder, R. A., Keppel-Aleks, G., Wunch, D., Yavin, Y., Allen, N. T., Blavier, J.-F., Jiménez, R., Daube, B. C., Bright, A. V., Matross, D. M., Wofsy, S. C., and Park, S.: Total column CO₂ measurements at Darwin, Australia – site description and calibration against in situ aircraft profiles, Atmos. Meas. Tech., 3, 947–958, https://doi.org/10.5194/amt-3-947-2010, 2010.

Deutscher, N. M., Notholt, J., Messerschmidt, J., Weinzierl, C., Warneke, T., Petri, C., and Grupe, P.: TCCON data from Bialystok (PL), Release GGG2014.R2, Version R2, CaltechDATA [data set], https://doi.org/10.14291/tccon.ggg2014.bialystok01.R2, 2019.

Duflot, V., Dils, B., Baray, J. L., De Mazière, M., Attié, J. L., Vahaelewyn, G., Senten, C., Vigouroux, C., Clain, G., and Delmas, R.: Analysis of the origin of the distribution of CO in the subtropical southern Indian Ocean in 2007, J. Geophys. Res., 115, D22106, https://doi.org/10.1029/2010JD013994, 2010.

ESA-EOPG-CSCOP-PL: Sentinel-5 Precursor Calibration and Validation Plan for the Operational Phase, Issue 1, Revision 1, 26 pp., available at: https://sentinel.esa.int/documents/247904/2474724/Sentinel-5P-Calibration-and-Validation-Plan.pdf (last access: 1 December 2020), 2017.

Feist, D. G., Arnold, S. G., John, N., and Geibel, M. C.: TCCON data from Ascension Island (SH), Release GGG2014.R0, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.ASCENSION01.R0/1149285, 2014.

Griffith, D. W. T., Deutscher, N. M., Velazco, V. A., Wennberg, P. O., Yavin, Y., Keppel-Aleks, G., Washenfelder, R. A., Toon, G. C., Blavier, J.-F., Paton-Walsh, C., Jones, N. B., Kettlewell, G. C., Connor, B. J., Macatangay, R. C., Roehl, C., Ryczek, M., Glowacki, J., Culgan, T., and Bryant, G. W.: TCCON data from Darwin (AU), Release GGG2014.R0, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.DARWIN01.R0/1149290, 2014a.

Griffith, D. W. T., Velazco, V. A., Deutscher, N. M., Paton-Walsh, C., Jones, N. B., Wilson, S. R., Macatangay, R. C., Kettlewell, G. C., Buchholz, R. R., and Riggenbach, M. O.: TCCON data from Wollongong (AU), Release GGG2014.R0, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.WOLLONGONG01.R0/1149291, 2014b.

Hannigan, J. W., Coffey, M. T., and Goldman, A.: Semiautonomous FTS Observation System for Remote Sensing of Stratospheric and Tropospheric Gases, J. Atmos. Ocean. Tech., 26, 1814–1828, https://doi.org/10.1175/2009JTECHA1230.1, 2009.

Hase, F., Hannigan, J., Coffey, M., Goldman, A., Höpfner, M., Jones, N., Rinsland, C., and Wood, S.: Intercomparison of retrieval codes used for the analysis of high-resolution, ground-based FTIR measurements, J. Quant. Spectrosc. Ra., 87, 25–52, https://doi.org/10.1016/j.qsrt.2003.12.008, 2004.

Hase, F., Blumenstock, T., Dohe, S., Groß, J., and Kiel, M.: TCCON data from Karlsruhe (DE), Release GGG2014.R1, Version GGG2014.R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.KARLSRUHE01.R1/1182416, 2015.

Hasekamp, O., Lorente, A., Hu, H., Butz, A., aan de Brugh, J., and Landgraf, J.: Algorithm Theoretical Baseline Document for Sentinel-5 Precursor Methane Retrieval, SRON Netherlands Institute for Space Research, Document no.: SRON-S5P-LEV2-RP-001, available at: https://sentinel.esa.int/documents/247904/2476257/Sentinel-5P-TROPOMI-ATBD-Methane-retrieval (last access: 1 December 2020), 2019.

Hedelius, J. K., He, T.-L., Jones, D. B. A., Baier, B. C., Buchholz, R. R., De Mazière, M., Deutscher, N. M., Dubey, M. K., Feist, D. G., Griffith, D. W. T., Hase, F., Iraci, L. T., Jeseck, P., Kiel, M., Kivi, R., Liu, C., Morino, I., Notholt, J., Oh, Y.-S., Ohyama, H., Pollard, D. F., Rettinger, M., Roche, S., Roehl, C. M., Schneider, M., Shiomi, K., Strong, K., Sussmann, R., Sweeney, C., Té, Y., Uchino, O., Velazco, V. A., Wang, W., Warneke, T., Wennberg, P. O., Worden, H. M., and Wunch, D.: Evaluation of MOPITT Version 7 joint TIR–NIR $X_{CO}$ retrievals with TCCON, Atmos. Meas. Tech., 12, 5547–5572, https://doi.org/10.5194/amt-12-5547-2019, 2019.

Hochstaffl, P., Schreier, F., Lichtenberg, G., and Gimeno García, S.: Validation of Carbon Monoxide Total Column Retrievals from SCIAMACHY Observations with NDACC/TCCON Ground-Based Measurements, Remote Sens., 10, 223, https://doi.org/10.3390/rs10020223, 2018.

Hu, H., Hasekamp, O., Butz, A., Galli, A., Landgraf, J., Aan de Brugh, J., Borsdorff, T., Scheepmaker, R., and Aben, I.: The
operational methane retrieval algorithm for TROPOMI, Atmos. Meas. Tech., 9, 5423-5440, https://doi.org/10.5194/amt-9-5423-2016, 2016.

Iraci, L. T., Podolske, J. R., Hillyard, P. W., Roehl, C., Wennberg, P. O., Blavier, J.-F., Landeros, J., Allen, N., Wunch, D., Zavaleta, J., Quigley, E., Osterman, G. B., Albertson, R., Dunwoody, K., and Boyden, H.: TCCON data from Edwards (US), Release GGG2014.R1, Version GGG2014.R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.EDWARDS01.R1/1255068, 2016.

Iwasaki, C., Imasu, R., Bril, A., Yokota, T., Yoshida, Y., Morino, I., Oshchepkov, S., Wunch, D., Griffith, D. W. T., Deutscher, N. M., Kivi, R., Pollard, D., Roehl, C. M., Velazco, V. A., Sussmann, R., Warneke, T., and Notholt, J.: Validation of GOSAT SWIR XCO₂ and XCH₄ Retrieved by PPDF-S Method and Comparison with Full Physics Method, SOLA, 13, 168–173, https://doi.org/10.2151/sola.2017-031, 2017.

Kawakami, S., Ohyama, H., Arai, K., Okumura, H., Taura, C., Fukamachi, T., and Sakashita, M.: TCCON data from Saga (JP), Release GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.SAGA01.R0/1149283, 2014.

Kiel, M., Hase, F., Blumenstock, T., and Kirner, O.: Comparison of XCO abundances from the Total Carbon Column Observing Network and the Network for the Detection of Atmospheric Composition Change measured in Karlsruhe, Atmos. Meas. Tech., 9, 2223–2239, https://doi.org/10.5194/amt-9-2223-2016, 2016.

Kirschke, S., Bousquet, P., Ciais, P., Saunois, M., Canadell, J. G., Dlugokencky, E. J., Bergamaschi, P., Bergmann, D., Blake, D. R., Bruhwiler, L., Cameron-Smith, P., Castaldi, S., Chevallier, F., Feng, L., Fraser, A., Heimann, M., Hodson, E. L., Houweling, S., Josse, B., Fraser, P. J., Krummel, P. B., Lamarque, J.-F., Langenfelds, R. L., Le Quéré, C., Naik, V., O'Doherty, S., Palmer, P. I., Pison, I., Plummer, D., Poulter, B., Prinn, R. G., Rigby, M., Ringeval, B., Santini, M., Schmidt, M., Shindell, D. T., Simpson, I. J., Spahni, R., Steele, L. P., Strode, S. A., Sudo, K., Szopa, S., van der Werf, G. R., Voulgarakis, A., van Weele, M., Weiss, R. F., Williams, J. E., and Zeng, G.: Three decades of global methane sources and sinks, Nat. Geosci., 6, 813–823, https://doi.org/10.1038/ngeo1955, 2013.

Kivi, R. and Heikkinen, P.: Fourier transform spectrometer measurements of column CO₂ at Sodankylä, Finland, Geosci. Instrum. Method. Data Syst., 5, 271–279, https://doi.org/10.5194/gi-5-271-2016, 2016.

Kivi, R., Heikkinen, P., and Kyrö, E.: TCCON data from Sodankylä (FI), Release GGG2014.R0, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.SODANKYLA01.R0/1149280, 2014.

Kulawik, S., Wunch, D., O'Dell, C., Frankenberg, C., Reuter, M., Oda, T., Chevallier, F., Sherlock, V., Buchwitz, M., Osterman, G., Miller, C. E., Wennberg, P. O., Griffith, D., Morino, I., Dubey, M. K., Deutscher, N. M., Notholt, J., Hase, F., Warneke, T., Sussmann, R., Robinson, J., Strong, K., Schneider, M., De Mazière, M., Shiomi, K., Feist, D. G., Iraci, L. T., and Wolf, J.: Consistent evaluation of ACOS-GOSAT, BESD-SCIAMACHY, CarbonTracker, and MACC through comparisons to TCCON, Atmos. Meas. Tech., 9, 683–709, https://doi.org/10.5194/amt-9-683-2016, 2016.

Lambert, J.-C., Compernolle, S., Eichmann, K.-U., de Graaf, M., Hubert, D., Keppens, A., Kleipool, Q., Langerock, B., Sha,

M. K., Verhoelst, T., Wagner, T., Ahn, C., Argyrouli, A., Balis, D., Chan, K., De Smedt, I., Eskes, H., Fjæraa, A., Garane, K., Gleason, J., Goutail, F., Granville, J., Hedelt, P. Heue, K.-P., Jaross, G., Koukouli, M., Landgraf, J., Lutz, R., Nanda, S., Niemejer, S., Pazmiño, A., Pinardi, G., Pommereau, J.-P., Richter, A., Rozemeijer, N., Sniep, M., SteinZweers, D., Theys, N., Tilstra, G., Torres, O., Valks, P., van Geffen, J., Vigouroux, C., Wang, P., and Weber, M.: Quarterly Validation Report of the Copernicus Sentinel-5 Precursor Operational Data Products #08: April 2018–August 2020, Document ID S5P-MPC-IASB-ROCVR-08.01.01-20200921, 170 pp., available at: https://mpc-vdaf.tropomi.eu/ProjectDir/reports/pdf/S5P-MPC-IASB-ROCVR-08.01.01-20200921_FINAL.pdf (last access: 1 December 2020), 2020.

Landgraf, J., aan de Brugh, J., Scheepmaker, R., Borsdorff, T., Hu, H., Houweling, S., Butz, A., Aben, I., and Hasekamp, O.: Carbon monoxide total column retrievals from TROPOMI short-wave infrared measurements, Atmos. Meas. Tech., 9, 4955–4975, https://doi.org/10.5194/amt-9-4955-2016, 2016.

Landgraf, J., aan de Brugh, J., Scheepmaker, R., Borsdorff, T., Houweling, S., and Hasekamp, O.: Algorithm Theoretical Baseline Document for Sentinel-5 Precursor: Carbon Monoxide Total Column Retrieval, SRON Netherlands Institute for Space Research, Document no.: SRON-S5P-LEV2-RP-002, 82 pp., available at: https://sentinel.esa.int/documents/247904/2476257/Sentinel-5P-TROPOMI-ATBD-Carbon-Monoxide-Total-Column-Retrieval (last access: 1 December 2020), 2018.

Langerock, B., De Mazière, M., Hendrick, F., Vigouroux, C., Desmet, F., Dils, B., and Niemeijer, S.: Description of algorithms for co-locating and comparing gridded model data with remote-sensing observations, Geosci. Model Dev., 8, 911–921, https://doi.org/10.5194/gmd-8-911-2015, 2015.

Lorente, A., Borsdorff, T., Butz, A., Hasekamp, O., aan de Brugh, J., Schneider, A., Wu, L., Hase, F., Kivi, R., Wunch, D., Pollard, D. F., Shiomi, K., Deutscher, N. M., Velazco, V. A., Roehl, C. M., Wennberg, P. O., Warneke, T., and Landgraf, J.: Methane retrieved from TROPOMI: improvement of the data product and validation of the first 2 years of measurements, Atmos. Meas. Tech., 14, 665–684, https://doi.org/10.5194/amt-14-665-2021, 2021.

Makarova, M. V., Kirner, O., Timofeev, Y. M., Poberovskii, A. V., Imkhasin, K. K., Osipov, S. I., and Makarov, B. K.: Annual cycle and long-term trend of the methane total column in the atmosphere over the St. Petersburg region, Izvestiya, Atmospheric and Oceanic Physics, 51, 431–438, https://doi.org/10.1134/S0001433815040088, 2015.

Morino, I., Matsuzaki, T., and Horikawa, M.: TCCON data from Tsukuba (JP), 125HR, Release GGG2014.R2, Version R2, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.TSUKUBA02.R2, 2018a.

Morino, I., Velazco, V. A., Hori, A., Uchino, O., and Griffith, D. W. T.: TCCON data from Burgos, Ilocos Norte (PH), Release GGG2014.R0, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.BURGOS01.R0, 2018b.

Morino, I., Yokozeki, N., Matsuzaki, T., and Horikawa, M.: TCCON data from Rikubetsu (JP), Release GGG2014.R2, Version
R2, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.RIKUBETSU01.R2, 2018c.

Notholt, J., Petri, C., Warneke, T., Deutscher, N. M., Palm, M., Buschmann, M., Weinzierl, C., Macatangay, R. C., and Grupe, P.: TCCON data from Bremen (DE), Release GGG2014.R0, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.BREMEN01.R0/1149275, 2014a.

Notholt, J., Warneke, T., Petri, C., Deutscher, N. M., Weinzierl, C., Palm, M., and Buschmann, M.: TCCON data from Ny Ålesund, Spitsbergen (NO), Release GGG2014.R0, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.NYALESUND01.R0/1149278, 2014b.

Novelli, P. C., Masarie, K. A., and Lang, P. M.: Distributions and recent changes of carbon monoxide in the lower troposphere, J. Geophys. Res., 103, 19015–19033, https://doi.org/10.1029/98JD01366, 1998.

O'Dell, C. W., Eldering, A., Wennberg, P. O., Crisp, D., Gunson, M. R., Fisher, B., Frankenberg, C., Kiel, M., Lindqvist, H., Mandrake, L., Merrelli, A., Natraj, V., Nelson, R. R., Osterman, G. B., Payne, V. H., Taylor, T. E., Wunch, D., Drouin, B. J., Oyafuso, F., Chang, A., McDuffie, J., Smyth, M., Baker, D. F., Basu, S., Chevallier, F., Crowell, S. M. R., Feng, L., Palmer, P. I., Dubey, M., García, O. E., Griffith, D. W. T., Hase, F., Iraci, L. T., Kivi, R., Morino, I., Notholt, J., Ohyama, H., Petri, C., Roehl, C. M., Sha, M. K., Strong, K., Sussmann, R., Te, Y., Uchino, O., and Velazco, V. A.: Improved retrievals of carbon dioxide from Orbiting Carbon Observatory-2 with the version 8 ACOS algorithm, Atmos. Meas. Tech., 11, 6539–6576, https://doi.org/10.5194/amt-11-6539-2018, 2018.

Olsen, K. S., Strong, K., Walker, K. A., Boone, C. D., Raspollini, P., Plieninger, J., Bader, W., Conway, S., Grutter, M., Hannigan, J. W., Hase, F., Jones, N., de Mazière, M., Notholt, J., Schneider, M., Smale, D., Sussmann, R., and Saitoh, N.: Comparison of the GOSAT TANSO-FTS TIR CH₄ volume mixing ratio vertical profiles with those measured by ACE-FTS, ESA MIPAS, IMKIAA MIPAS, and 16 NDACC stations, Atmos. Meas. Tech., 10, 3697–3718, https://doi.org/10.5194/amt-10-3697-2017, 2017.

Ortega, I., Buchholz, R. R., Hall, E. G., Hurst, D. F., Jordan, A. F., and Hannigan, J. W.: Tropospheric water vapor profiles obtained with FTIR: comparison with balloon-borne frost point hygrometers and influence on trace gas retrievals, Atmos. Meas. Tech., 12, 873–890, https://doi.org/10.5194/amt-12-873-2019, 2019.

Ostler, A., Sussmann, R., Rettinger, M., Deutscher, N. M., Dohe, S., Hase, F., Jones, N., Palm, M., and Sinnhuber, B.-M.: Multistation intercomparison of column-averaged methane from NDACC and TCCON: impact of dynamical variability, Atmos. Meas. Tech., 7, 4081–4101, https://doi.org/10.5194/amt-7-4081-2014, 2014.

Petri, C., Rousogenous, C., Warneke, T., Vrekoussis, M., Sciare, J., and Notholt, J.: TCCON data from Nicosia, Cyprus (CY), Release GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/tccon.ggg2014.nicosia01.R0, 2019.

Plaza-Medina, E. F., Stremme, W., Bezanilla, A., Grutter, M., Schneider, M., Hase, F., and Blumenstock, T.: Ground-based remote sensing of O₃ by high- and medium-resolution FTIR spectrometers over the Mexico City basin, Atmos. Meas. Tech., 10, 2703–2725, https://doi.org/10.5194/amt-10-2703-2017, 2017.

Pollard, D. F., Robinson, J., and Shiona, H.: TCCON data from Lauder (NZ), Release GGG2014.R0, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.R0, 2019.

Pouatchev, N. S., Connor, B. J., and Rinsland, C. P.: Infrared measurements of the ozone vertical distribution above Kitt Peak, J. Geophys. Res., 100, 16689–16697, https://doi.org/10.1029/95JD01296, 1995.

Rodgers, C. D. and Connor, B. J.: Intercomparison of remote sounding instruments, J. Geophys. Res., 108, 4116, https://doi.org/10.1029/2002JD002299, 2003.

Schneising, O., Buchwitz, M., Reuter, M., Bovensmann, H., Burrows, J. P., Borsdorff, T., Deutscher, N. M., Feist, D. G., Griffith, D. W. T., Hase, F., Hermans, C., Iraci, L. T., Kivi, R., Landgraf, J., Morino, I., Notholt, J., Petri, C., Pollard, D. F., Roche, S., Shiomi, K., Strong, K., Sussmann, R., Velazco, V. A., Warneke, T., and Wunch, D.: A scientific algorithm to simultaneously retrieve carbon monoxide and methane from TROPOMI onboard Sentinel-5 Precursor, Atmos. Meas. Tech., 12, 6771–6802, https://doi.org/10.5194/amt-12-6771-2019, 2019.

Schneising, O., Buchwitz, M., Reuter, M., Bovensmann, H., and Burrows, J. P.: Severe Californian wildfires in November 2018 observed from space: the carbon monoxide perspective, Atmos. Chem. Phys., 20, 3317–3332, https://doi.org/10.5194/acp-20-3317-2020, 2020a.

Schneising, O., Buchwitz, M., Reuter, M., Vanselow, S., Bovensmann, H., and Burrows, J. P.: Remote sensing of methane leakage from natural gas and petroleum systems revisited, Atmos. Chem. Phys., 20, 9169–9182, https://doi.org/10.5194/acp-20-9169-2020, 2020b.

Sepúlveda, E., Schneider, M., Hase, F., García, O. E., Gomez-Pelaez, A., Dohe, S., Blumenstock, T., and Guerra, J. C.: Long-term validation of tropospheric column-averaged CH₄ mole fractions obtained by mid-infrared ground-based FTIR spectrometry, Atmos. Meas. Tech., 5, 1425–1441, https://doi.org/10.5194/amt-5-1425-2012, 2012.

Sepúlveda, E., Schneider, M., Hase, F., Barthlott, S., Dubravica, D., García, O. E., Gomez-Pelaez, A., González, Y., Guerra, J. C., Gisi, M., Kohlhepp, R., Dohe, S., Blumenstock, T., Strong, K., Weaver, D., Palm, M., Sadeghi, A., Deutscher, N. M., Warneke, T., Notholt, J., Jones, N., Griffith, D. W. T., Smale, D., Brailsford, G. W., Robinson, J., Meinhardt, F., Steinbacher, M., Aalto, T., and Worthy, D.: Tropospheric CH₄ signals as observed by NDACC FTIR at globally distributed sites and comparison to GAW surface in situ measurements, Atmos. Meas. Tech., 7, 2337–2360, https://doi.org/10.5194/amt-7-2337-2014, 2014.

Sha, M. K., Langerock, B., De Mazière, M., Dils, B., Feist, D. G., Sussmann, R., Hase, F., Schneider, M., Blumenstock, T., Notholt, J., Warneke, T., Petri, C., Kivi, R., Te, Y., Wennberg, P. O., Wunch, D., Iraci, L. T., Strong, K., Griffith, D. W. T., Deutscher, N. M., Velazco, V. A., Morino, I., Ohyama, H., Uchino, O., Shiomi, K., Goo, T. Y., Pollard, D. F., Borsdorff, T., Hu, H., Hasekamp, O. P., Landgraf, J., Roehl, C. M., Kiel, M., Toon, G., and TCCON team: First results of the Sentinel-5 Precursor CO and CH₄ validation using TCCON data (ESA AO project TC-CON4S5P) and NDACC CO data, in: NDACC-IRWG-TCCON Annual Meeting, Mexico City, Mexico, 11–15 June 2018, available at: https://sites.google.com/site/irwgtccon2018/ (last access: 1 December 2020), 2018a.

Sha, M. K., Langerock, B., De Mazière, M., Dils, B., Feist, D. G., Sussmann, R., Hase, F., Schneider, M., Blumenstock, T., Notholt, J., Warneke, T., Petri, C., Kivi, R., Te, Y., Wennberg, P. O., Wunch, D., Iraci, L. T., Strong, K., Griffith, D. W. T., Deutscher, N. M., Velazco, V. A., Morino, I., Ohyama, H., Uchino, O., Shiomi, K., Goo, T. Y., Pollard, D. F., Borsdorff, T., Hu, H., Hasekamp, O. P., Landgraf, J., Roehl, C. M., Kiel, M., Toon, G., and TCCON team: First results of the Sentinel-5 Precursor CO and CH₄ validation using TCCON data (ESA AO project TC-CON4S5P) and NDACC CO data, in: NDACC-IRWG-TCCON Annual Meeting, Mexico City, Mexico, 11–15 June 2018, available at: https://sites.google.com/site/irwgtccon2018/ (last access: 1 December 2020), 2018a.
T., Notholt, J., Warneke, T., Petri, C., Kivi, R., Te, Y., Wennberg, P. O., Wunch, D., Iraci, L. T., Strong, K., Griffith, D. W. T., Deutscher, N. M., Velazco, V. A., Morino, I., Ohyama, H., Uchino, O., Shiomi, K., Goo, T. Y., Pollard, D. F., Borsdorff, T., Hu, H., Hasekamp, O. P., Landgraf, J., Roehl, C. M., Kiel, M., Toon, G., TCCON team, and NDACC team: VDAF CO validation results & ESA AO # 28603 project TCCON4S5P first CO validation results using TCCON and NDACC data, in: S5P First products release workshop, ESA-Esrin, Frascati (Rome), Italy, 25-26 June 2018, available at: https://nikal.eventsair.com/QuickEventWebsitePortal/sentinel-5p-first-product-release-workshop/sentinel-5p (last access: 1 December 2020), 2018b.

Sha, M. K., De Mazière, M., Notholt, J., Blumenstock, T., Chen, H., Dehn, A., Griffith, D. W. T., Hase, F., Heikkinen, P., Hermans, C., Hoffmann, A., Huebner, M., Jones, N., Kivi, R., Langerock, B., Petri, C., Scolas, F., Tu, Q., and Weidmann, D.: Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO₂, CH₄, and CO, Atmos. Meas. Tech., 13, 4791–4839, https://doi.org/10.5194/amt-13-4791-2020, 2020.

Sherlock, V., Connor, B., Robinson, J., Shiona, H., Smale, D., and Pollard, D. F.: TCCON data from Lauder (NZ), 125HR, Release GGG2014.R0, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.LAUDER02.R0/1149298, 2014.

Stocker, T. F., Qin, D., Plattner, G.-K., Alexander, L., Allen, S., Bindoff, N., Bréon, F.-M., Church, J., Cubasch, U., Emori, S., Forster, P., Friedlingstein, P., Gillett, N., Gregory, J., Hartmann, D., Jansen, E., Kirtman, B., Knutti, R., Kumar, K. K., Lemke, P., Marotzke, J., Masson-Delmotte, V., Meehl, G., Mokhov, I., S.Piao, Ramaswamy, V., Randall, D., Rhein, M., Rojas, M., Sabine, C., Shindell, D., Talley, L., Vaughan, D., and Xie, S.-P.: Technical Summary, in: Climate Change 2013: The Physical Science Basis, Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Stocker, T. F., Qin, D., Plattner, G.-K., Tignor, M., Allen, S. K., Boschung, J., Nauels, A., Xia, Y., Bex, V., and Midgley, P. M., Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2013.

Stremme, W., Grutter, M., Rivera, C., Bezanilla, A., Garcia, A. R., Ortega, I., George, M., Clerbaux, C., Coheur, P.-F., Hurtmans, D., Hannigan, J. W., and Coffey, M. T.: Top-down estimation of carbon monoxide emissions from the Mexico Megacity based on FTIR measurements from ground and space, Atmos. Chem. Phys., 13, 1357–1376, https://doi.org/10.5194/acp-13-1357-2013, 2013.

Strong, K., Roche, S., Franklin, J. E., Mendonca, J., Lutsch, E., Weaver, D., Fogal, P. F., Drummond, J. R., Batchelor, R., and Lindenmaier, R.: TCCON data from Eureka (CA), Release GGG2014.R3, Version R3, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.EUREKA01.R3, 2019.

Sussmann, R. and Rettinger, M.: TCCON data from Garmisch (DE), Release GGG2014.R2, Version R2, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.GARMISCH01.R2, 2018a.

Sussmann, R. and Rettinger, M.: TCCON data from Zugspitze (DE), Release GGG2014.R1, Version R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.ZUGSPITZE01.R1, 2018b.

Té, Y., Jeseck, P., Franco, B., Mahieu, E., Jones, N., Paton-Walsh, C., Griffith, D. W. T., Buchholz, R. R., Hadji-Lazaro, J., Hurtmans, D., and Janssen, C.: Seasonal variability of surface and column carbon monoxide over the megacity Paris, high-altitude Jungfraujoch and Southern Hemispheric Wollongong stations, Atmos. Chem. Phys., 16, 10911–10925, https://doi.org/10.5194/acp-16-10911-2016, 2016.

Té, Y., Jeseck, P., and Janssen, C.: TCCON data from Paris (FR), Release GGG2014.R0, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.PARIS01.R0/1149279, 2014.

Toon, G. C. and Wunch, D.: A stand-alone a priori profile generation tool for GGG2014 release, Version GGG2014.R0, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.PRIORS.R0/1221661, 2015.

Total Carbon Column Observing Network (TCCON) Team: 2014 TCCON Data Release, Version GGG2014, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014, 2017.

Veefkind, J., Aben, I., McMullan, K., Förster, H., de Vries, J., Otter, G., Claas, J., Eskes, H., de Haan, J., Kleipool, Q., van Weele, M., Hasekamp, O., Hoogeveen, R., Landgraf, J., Snel, R., Tol, P., Ingmann, P., Voors, R., Kruizinga, B., Vink, R., Visser, H., and Levelt, P.: TROPOMI on the ESA Sentinel-5 Precursor: A GMES mission for global observations of the atmospheric composition for climate, air quality and ozone layer applications, Remote Sens. Environ., 120, 70–83, https://doi.org/10.1016/j.rse.2011.09.027, 2012.

Velazco, V., Morino, I., Uchino, O., Hori, A., Kiel, M., Bukosa, B., Deutscher, N., Sakai, T., Nagai, T., Bagtasa, G., Izumi, T., Yoshida, Y., and Griffith, D.: TCCON Philipines: First Measurement Results, Satellite Data and Model Comparisons in Southeast Asia, Remote Sensing, 9, 1228, https://doi.org/10.3390/rs9121228, 2017.

Vellalassery, A., Pillai, D., Marshall, J., Gerbig, C., Buchwitz, M., Schneising, O., and Ravi, A.: Using TROPOspheric Monitoring Instrument (TROPOMI) measurements and Weather Research and Forecasting (WRF) CO modelling to understand the contribution of meteorology and emissions to an extreme air pollution event in India, Atmos. Chem. Phys., 21, 5393–5414, https://doi.org/10.5194/acp-21-5393-2021, 2021.

Warneke, T., Messerschmidt, J., Notholt, J., Weinzierl, C., Deutscher, N. M., Petri, C., and Grupe, P.: TCCON data from Orléans (FR), Release GGG2014.R1, Version R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.ORLEANS01.R1, 2019.

Wennberg, P. O., Wunch, D., Roehl, C. M., Blavier, J.-F., Toon, G. C., and Allen, N. T.: TCCON data from Caltech (US), Release GGG2014.R1, Version GGG2014.R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.PASADENA01.R1/1182415, 2015.

Wennberg, P. O., Roehl, C. M., Blavier, J.-F., Wunch, D., and Allen, N. T.: TCCON data from Jet Propulsion Laboratory (US), 2011, Release GGG2014.R1, Version GGG2014.R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.JPL02.R1/1330096, 2016a.

Wennberg, P. O., Wunch, D., Roehl, C. M., Blavier, J.-F., Toon, G. C., and Allen, N. T.: TCCON data from Lamont (US), Re-
lease GGG2014.R1, Version GGG2014.R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.LAMONT01.R1/1255070, 2016b.

Wennberg, P. O., Roehl, C. M., Wunch, D., Toon, G. C., Blavier, J.-F., Washenfelder, R., Keppel-Aleks, G., Allen, N. T., and Ayers, J.: TCCON data from Park Falls (US), Release GGG2014.R1, Version GGG2014.R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.PARKFALLS01.R1, 2017.

Wiacek, A., Taylor, J. R., Strong, K., Saari, R., Kerzenmacher, T. E., Jones, N. B., and Griffith, D. W. T.: Ground-Based Solar Absorption FTIR Spectroscopy: Characterization of Retrievals and First Results from a Novel Optical Design Instrument at a New NDACC Complementary Station, J. Atmos. Ocean. Tech., 24, 432–448, https://doi.org/10.1175/JTECH1962.1, 2007.

Wunch, D., Toon, G. C., Blavier, J.-F. L., Washenfelder, R. A., Notholt, J., Connor, B. J., Griffith, D. W. T., Sherlock, V., and Wennberg, P. O.: The Total Carbon Column Observing Network, Philos. T. Roy. Soc. A, 369, 2087–2112, https://doi.org/10.1098/rsta.2010.0240, 2011.

Wunch, D., Toon, G. C., Sherlock, V., Deutscher, N. M., Liu, C., Feist, D. G., and Wennberg, P. O.: The Total Carbon Column Observing Network's GGG2014 Data Version, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A., Version: GGG2014.R0, 42 pp., https://doi.org/10.14291/tccon.ggg2014/documentation.R0/1221662, 2015.

Wunch, D., Wennberg, P. O., Osterman, G., Fisher, B., Naylor, B., Roehl, C. M., O'Dell, C., Mandrake, L., Viatte, C., Kiel, M., Griffith, D. W. T., Deutscher, N. M., Velazco, V. A., Notholt, J., Warneke, T., Petri, C., De Mazière, M., Sha, M. K., Sussmann, R., Rettinger, M., Pollard, D., Robinson, J., Morino, I., Uchino, O., Hase, F., Blumenstock, T., Feist, D. G., Arnold, S. G., Strong, K., Mendonca, J., Kivi, R., Heikkinen, P., Iraci, L., Podolske, J., Hillyard, P. W., Kawakami, S., Dubey, M. K., Parker, H. A., Sepulveda, E., García, O. E., Te, Y., Jeseck, P., Gunson, M. R., Crisp, D., and Elderling, A.: Comparisons of the Orbiting Carbon Observatory-2 (OCO-2) $X_{CO_2}$ measurements with TCCON, Atmos. Meas. Tech., 10, 2209–2238, https://doi.org/10.5194/amt-10-2209-2017, 2017.

Wunch, D., Mendonca, J., Colebatch, O., Allen, N. T., Blavier, J.-F., Roche, S., Hedelius, J., Neufeld, G., Springett, S., Worthy, D., Kessler, R., and Strong, K.: TCCON data from East Trout Lake, SK (CA), Release GGG2014.R1, Version R1, CaltechDATA [data set], https://doi.org/10.14291/TCCON.GGG2014.EASTTROUTLAKE01.R1, 2018.

Yang, Y., Zhou, M., Langerock, B., Sha, M., Hermans, C., Wang, T., Ji, D., Vigouroux, C., Kumps, N., Wang, G., De Mazière, M., and Wang, P.: Ground-based FTIR CO2, CH4 and CO measurements at Xianghe, China, Royal Belgian Institute for Space Aeronomy [data set], https://doi.org/10.18758/71021049, 2019.

Yurganov, L. N., Blumenstock, T., Grechko, E. I., Hase, F., Hyer, E. J., Kasischke, E. S., Koike, M., Kondo, Y., Kramer, I., Leung, F.-Y., Mahieu, E., Mellqvist, J., Notholt, J., Novelli, P. C., Rinsland, C. P., Scheel, H. E., Schulz, A., Strandberg, A., Sussmann, R., Tanimoto, H., Velazco, V., Zander, R., and Zhao, Y.: A quantitative assessment of the 1998 carbon monoxide emission anomaly in the Northern Hemisphere based on total column and surface concentration measurements, J. Geophys. Res., 109, D15305, https://doi.org/10.1029/2004JD004559, 2004.

Zeng, G., Wood, S. W., Morgenstern, O., Jones, N. B., Robinson, J., and Smale, D.: Trends and variations in CO, $C_2H_6$, and HCN in the Southern Hemisphere point to the declining anthropogenic emissions of CO and $C_2H_6$, Atmos. Chem. Phys., 12, 7543–7555, https://doi.org/10.5194/acp-12-7543-2012, 2012.

Zhou, M., Langerock, B., Vigouroux, C., Sha, M. K., Ramonet, M., Delmotte, M., Mahieu, E., Bader, W., Hermans, C., Kumps, N., Metzger, J.-M., Duflot, V., Wang, Z., Palm, M., and De Mazière, M.: Atmospheric CO and $CH_4$ time series and seasonal variations on Reunion Island from ground-based in situ and FTIR (NDACC and TCCON) measurements, Atmos. Chem. Phys., 18, 13881–13901, https://doi.org/10.5194/acp-18-13881-2018, 2018.

Zhou, M., Langerock, B., Vigouroux, C., Sha, M. K., Hermans, C., Metzger, J.-M., Chen, H., Ramonet, M., Kivi, R., Heikkinen, P., Smale, D., Pollard, D. F., Jones, N., Velazco, V. A., García, O. E., Schneider, M., Palm, M., Warneke, T., and De Mazière, M.: TCCON and NDACC $X_{CO}$ measurements: difference, discussion and application, Atmos. Meas. Tech., 12, 5979–5995, https://doi.org/10.5194/amt-12-5979-2019, 2019.