Total Carbon Column Observing Network

The Total Carbon Column Observing Network (TCCON) is a global network of instruments that measure the amount of carbon dioxide, methane, carbon monoxide, nitrous oxide and other trace gases in the Earth's atmosphere. The TCCON (/ˈtiːkɒn/ TEE-kon) began in 2004 with the installation of the first instrument in Park Falls, Wisconsin, USA, and has since grown to 23 operational instruments worldwide, with 7 former sites.[1]

Total Carbon Column Observing Network
AbbreviationTCCON
Formation26 May 2004 (2004-05-26)
TypeInternational collaborative network
Productscolumn GHG measurements
Methodsnear-IR solar spectroscopy
Chair
Debra Wunch (2020-23)
Co-chair (Europe / Africa)
Thorsten Warneke (2020-23)
Co-chair (W. Pacific / Asia)
Nicholas Deutscher (2020-23)
Regions- InstrumentationBruker 125HR spectrometer
SoftwareGGG2014 / GGG2020
Sites23 (2015)
Primary Gases (columns)CO2, CH4, CO, N2O, HF, H2O

The TCCON is designed to investigate several things, including the flow (or flux) of carbon between the atmosphere, land, and ocean (the so-called carbon budget or carbon cycle). This is achieved by measuring the atmospheric mass of carbon (the airborne fraction). The TCCON measurements have improved the scientific community's understanding of the carbon cycle,[2][3] and urban greenhouse gas emissions.[4]

The TCCON supports several satellite instruments by providing an independent measurement to compare (or validate) the satellite measurements of the atmosphere over the TCCON site locations.[5][6] The TCCON provides the primary measurement validation dataset for the Orbiting Carbon Observatory (OCO-2) mission,[7] and has been used to validate other space-based measurements of carbon dioxide.

History

The TCCON was established partly because of modeling errors between mixing efficiency between the PBL and the free troposphere.[2] Because TCCON measurements are of the entire column of atmosphere above a site (PBL and free troposphere are simultaneously measured) the measurements are an improvement over the traditional in situ near surface measurements in this regard. TCCON has improved the CO2 mass gradient measurements between the northern and southern hemispheres.

The first annual TCCON meeting was in San Francisco, California in 2005. Every year a meeting is held in a location that rotates between North America, the Western Pacific, and Europe hosted by a participating institution. In 2015 the meeting was held at the University of Toronto.[8]

Cartoon oversimplification of column gas measurements by TCCON & satellite. O2 & the gas of interest are measured & ratioed for a column averaged amount.
Cartoon oversimplification of column gas measurements by TCCON & satellite. O2 & the gas of interest are measured & ratioed for a column averaged amount.

Measurement technique

The main instrument at each TCCON site is a Bruker IFS 125HR (HR for high resolution, ~0.02 cm−1) or occasionally 120HR Fourier transform spectrometer. Sunlight is directed into the spectrometer by solar tracking mirrors and other optics. The spectrometers measure the absorption of direct sunlight by atmospheric trace gases primarily in the near infrared region. This remote sensing technique produces a precise and accurate measurement of the total column abundance of the trace gas. The main limitation to this technique is that measurements can not be recorded when it is not sunny (i.e. there are no measurements available at nighttime or when there is heavy cloud cover).[9]

Participating sites and Institutions

Current TCCON sites are located in the United States, China, Canada, Germany, Poland, France, Japan, Australia, New Zealand, South Korea, Réunion, and Ascension Island.[1] A former site was in Brazil. Sites can change when an instrument needs to be moved to a new location.

TCCON members collaborate from a variety of different institutions. In North America some of these include Caltech, JPL, Los Alamos National Laboratory, NASA Ames, and the University of Toronto. In Europe some of these include Karlsruhe Institute of Technology, Max Planck Institute for Biogeochemistry, University of Bremen, Agencia Estatal de Meteorología, Royal Belgian Institute for Space Aeronomy, Finnish Meteorological Institute, and Pierre and Marie Curie University. In the western Pacific some of these include University of Wollongong, National Institute of Water and Atmospheric Research, National Institute for Environmental Studies, JAXA, and National Institute of Meteorological Research of the Republic of Korea.

New sites are admitted into the network when site investigators demonstrate required hardware, and data processing ability. Uniformity is maintained across the network by using the same FTS model and the same retrieval software. GGG is the software of the TCCON.[1] It includes the I2S (interferogram to spectrum) FFT, and GFIT spectral fitting subroutines. GFIT is also the fitting algorithm that was used for ATMOS which flew on the Space Shuttle,[10] and is used for spectral fitting of spectra obtained by a balloon borne spectrometer.[11]

Map
TCCON sites around the globe, as of January 2020.[8]   green = active and public data available,   cyan = active and no public data yet,   white= former and public data,   yellow = potential future site

Highlights of Data Use

Data from each site is processed by the investigators that head that particular site. Atmospheric abundances of gases are uploaded and saved in uniform formats and data are hosted at Caltech with the Caltech Library and are available from http://tccondata.org. Data are made publicly available provided the data license is followed.[12]

Data have been used for a variety of analyses. Some of these include

  • Emission estimates of methane and carbon monoxide were made for the South Coast Air Basin containing Los Angeles using TCCON measurements and the CARB inventory.[13]
  • Characterization of biosphere fluxes in the Southern Hemisphere [14]
  • Evaluation of the seasonal exchange of CO2 between the biosphere and the atmosphere [15]
  • Numerous satellite validation projects [16][17][18]
  • Validation projects involving comparison of CO2 and CH4 measured by TCCON with that measured by lower-resolution instruments[19][20]
  • Covariation between surface temperature and CO2 in boreal regions[21]
  • Distinguishing between which of two power plants (~2000 MW each) plumes of polluted air came from in conjunction with a Pandora NO2 spectrometer[22]

Satellite support

The satellite missions supported by the TCCON include the Greenhouse Gases Observing Satellite (GOSAT),[23][24][25] SCIAMACHY,[26] and the Orbiting Carbon Observatory-2 (OCO-2).[7]

See also

References
  1. Wunch, D.; Toon, G. C.; Sherlock, V.; Deutscher, N. M.; Liu, X.; Feist, D. G.; Wennberg, P. O. (2015). The Total Carbon Column Observing Network's GGG2014 Data Version (PDF). Oak Ridge, Tennessee, U.S.A.: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory. doi:10.14291/tccon.ggg2014.documentation.R0/1221662. Retrieved 12 May 2016.
  2. Yang, Z., R. A. Washenfelder, G. Keppel-Aleks, N. Y. Krakauer, J. T. Randerson, P. P. Tans, C. Sweeney, and P. O. Wennberg (2007), New constraints on Northern Hemisphere growing season net flux, Geophysical Research Letters, 34(12), 1-6, doi:10.1029/2007GL029742. Available from: http://www.agu.org/pubs/crossref/2007/2007GL029742.shtml
  3. Chevallier, F. et al. (2011), Global CO 2 fluxes inferred from surface air-sample measurements and from TCCON retrievals of the CO2 total column, Geophysical Research Letters, 38(24), 1-5, doi:10.1029/2011GL049899. Available from: http://www.agu.org/pubs/crossref/201...GL049899.shtml
  4. Verifying Greenhouse Gas Emissions: Methods to Support International Climate Agreements, http://www.nap.edu/catalog/12883.html
  5. "About GOSAT - GOSAT Project". www.gosat.nies.go.jp. Archived from the original on 2008-11-01.
  6. Boland, S. et al. (2009), The Need for Atmospheric Carbon Dioxide Measurements from Space : Contributions from a Rapid Reflight of the Orbiting Carbon Observatory, http://www.nasa.gov/pdf/363474main_OCO_Reflight.pdf
  7. NASA.gov
  8. TCCON Webpage, https://tccon-wiki.caltech.edu/Sites, accessed February 6, 2016
  9. Wunch, D., G. C. Toon, J.-F. L. Blavier, R. A. Washenfelder, J. Notholt, B. J. Connor, D. W. T. Griffith, V. Sherlock, and P. O. Wennberg (2011), The total carbon column observing network, Philosophical Transactions of the Royal Society - Series A: Mathematical, Physical and Engineering Sciences, 369(1943), 2087-2112, doi:10.1098/rsta.2010.0240. Available from: http://rsta.royalsocietypublishing.o.../2087.full.pdf
  10. JPL NASA ATMOS webpage, http://remus.jpl.nasa.gov/atmos/onshuttle.html, accessed February 6, 2016
  11. NASA JPL MkIV interferometer webpage https://airbornescience.nasa.gov/instrument/MkIV, accessed February 6, 2016
  12. TCCON data use policy webpage https://tccon-wiki.caltech.edu/Network_Policy/Data_Use_Policy, accessed February 6, 2016
  13. Wunch, D., P. O. Wennberg, G. C. Toon, G. Keppel-Aleks, and Y. G. Yavin (2009), Emissions of greenhouse gases from a North American megacity, Geophys. Res. Lett., 36, L15810, doi:10.1029/2009GL039825.
  14. Deutscher, N. M., Sherlock, V., Mikaloff Fletcher, S. E., Griffith, D. W. T., Notholt, J., Macatangay, R., Connor, B. J., Robinson, J., Shiona, H., Velazco, V. A., Wang, Y., Wennberg, P. O., and Wunch, D.: Drivers of column-average CO2 variability at Southern Hemispheric Total Carbon Column Observing Network sites, Atmos. Chem. Phys., 14, 9883-9901, doi:10.5194/acp-14-9883-2014, 2014.
  15. Messerschmidt, J., Parazoo, N., Wunch, D., Deutscher, N. M., Roehl, C., Warneke, T., and Wennberg, P. O.: Evaluation of seasonal atmosphere–biosphere exchange estimations with TCCON measurements, Atmos. Chem. Phys., 13, 5103-5115, doi:10.5194/acp-13-5103-2013, 2013.
  16. Wunch, D., et al.: A method for evaluating bias in global measurements of CO2 total columns from space, Atmos. Chem. Phys., 11, 12317-12337, doi:10.5194/acp-11-12317-2011, 2011.
  17. Dils, B., Buchwitz, M., Reuter, M., Schneising, O., Boesch, H., Parker, R., Guerlet, S., Aben, I., Blumenstock, T., Burrows, J. P., Butz, A., Deutscher, N. M., Frankenberg, C., Hase, F., Hasekamp, O. P., Heymann, J., De Mazière, M., Notholt, J., Sussmann, R., Warneke, T., Griffith, D., Sherlock, V., and Wunch, D.: The Greenhouse Gas Climate Change Initiative (GHG-CCI): comparative validation of GHG-CCI SCIAMACHY/ENVISAT and TANSO-FTS/GOSAT CO2 and CH4 retrieval algorithm products with measurements from the TCCON, Atmos. Meas. Tech., 7, 1723-1744, doi:10.5194/amt-7-1723-2014, 2014.
  18. M. Buchwitz et al.: The Greenhouse Gas Climate Change Initiative (GHG-CCI): Comparison and quality assessment of near-surface-sensitive satellite-derived CO2 and CH4 global data sets., Remote Sens. Environ., 162, 344-362, doi:10.1016/j.rse.2013.04.024, 2015.
  19. Gisi, M., Hase, F., Dohe, S., Blumenstock, T., Simon, A., and Keens, A.: XCO2-measurements with a tabletop FTS using solar absorption spectroscopy, Atmos. Meas. Tech., 5, 2969-2980, doi:10.5194/amt-5-2969-2012, 2012.
  20. Petri, C., Warneke, T., Jones, N., Ridder, T., Messerschmidt, J., Weinzierl, T., Geibel, M., and Notholt, J.: Remote sensing of CO2 and CH4 using solar absorption spectrometry with a low resolution spectrometer, Atmos. Meas. Tech., 5, 1627-1635, doi:10.5194/amt-5-1627-2012, 2012.
  21. Wunch, D., Wennberg, P. O., Messerschmidt, J., Parazoo, N. C., Toon, G. C., Deutscher, N. M., Keppel-Aleks, G., Roehl, C. M., Randerson, J. T., Warneke, T., and Notholt, J.: The covariation of Northern Hemisphere summertime CO2 with surface temperature in boreal regions, Atmos. Chem. Phys., 13, 9447-9459, doi:10.5194/acp-13-9447-2013, 2013.
  22. Rodica Lindenmaier, Manvendra K. Dubey, Bradley G. Henderson, Zachary T. Butterfield, Jay R. Herman, Thom Rahn, and Sang-Hyun Lee. Multiscale observations of CO2, 13CO2, and pollutants at Four Corners for emission verification and attribution. PNAS 2014 111 (23) 8386-8391; published ahead of print May 19, 2014, doi:10.1073/pnas.1321883111
  23. Crisp, D. et al.: The ACOS XCO2 retrieval algorithm, Part 2: Global XCO2 data characterization, Atmos. Meas. Tech. Discuss., 5, 1-60, doi:10.5194/amtd-5-1-2012, 2012, http://www.atmos-meas-tech-discuss.net/5/1/2012/amtd-5-1-2012.html
  24. Butz, A. et al. (2011), Toward accurate CO2 and CH4 observations from GOSAT, Geophysical Research Letters, 38(14), 2-7, doi:10.1029/2011GL047888, http://www.agu.org/pubs/crossref/2011/2011GL047888.shtml
  25. Morino, I. et al. (2011), Preliminary validation of column-averaged volume mixing ratios of carbon dioxide and methane retrieved from GOSAT short-wavelength infrared spectra, Atmospheric Measurement Techniques, 4(6), 1061-1076, doi:10.5194/amt-4-1061-2011, http://www.atmos-meas-tech.net/4/1061/2011/
  26. Buchwitz, M. et al. (2006), Atmospheric carbon gases retrieved from SCIAMACHY by WFM-DOAS: version 0.5 CO and CH4 and impact of calibration improvements on CO2 retrieval, Atmospheric Chemistry and Physics, 6(9), 2727-2751, doi:10.5194/acp-6-2727-2006, http://www.atmos-chem-phys.net/6/2727/2006/
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