Space-based measurements of carbon dioxide

Artist's conception of OCO-2, the second successful high precision (better than 0.3%) CO2 observing satellite.

Space-based measurements of carbon dioxide (CO2) are used to help answer questions about Earth's carbon cycle. There are a variety of active and planned instruments for measuring carbon dioxide in Earth's atmosphere from space. The first satellite mission designed to measure CO2 was the Interferometric Monitor for Greenhouse Gases (IMG) on board the ADEOS I satellite in 1996. This mission lasted less than a year. Since then, additional space-based measurements have begun, including those from two high-precision (better than 0.3% or 1 ppm) satellites (GOSAT and OCO-2). Different instrument designs may reflect different primary missions.

Purposes and highlights of findings

There are outstanding questions in carbon cycle science that satellite observations can help answer. The Earth system absorbs about half of all anthropogenic CO2 emissions.[1] However, it is unclear exactly how this uptake is partitioned to different regions across the globe. It is also uncertain how different regions will behave in terms of CO2 flux under a different climate. For example, a forest may increase CO2 uptake due to the fertilization or β-effect,[2] or it could release CO2 due to increased metabolism by microbes at higher temperatures.[3] These questions are difficult to answer with historically spatially and temporally limited data sets.

Even though satellite observations of CO2 are somewhat recent, they have been used for a number of different purposes, some of which are highlighted here.

  • Megacity CO2 enhancements were observed with the GOSAT satellite and minimum observable space-based changes in emissions were estimated.[4]
  • Satellite observations have been used for visualizing how CO2 is distributed globally,[5] including studies that have focused on anthropogenic emissions.[6]
  • Flux estimates were made of CO2 into and out of different regions.[7][8]
  • Correlations were observed between anomalous temperatures and CO2 measurements in boreal regions.[9]
  • Zonal asymmetric patterns of CO2 were used to observe fossil fuel signatures.[10]
  • Emission ratios with methane were measured from forest fires.[11]
  • CO2 emission ratios with carbon monoxide (a marker of incomplete combustion) measured by the MOPITT instrument were analyzed over major urban regions across the globe to measure developing/developed status.[12]
  • OCO-2 observations were used to estimate CO2 emissions from wildfires in Indonesia in 2015.[13]
  • OCO-2 observations were also used to estimate the excess land-ocean flux due to the 2014–16 El Niño event.[14]

Challenges

Remote sensing of trace gases has several challenges. Most techniques rely on observing infrared light reflected off Earth's surface. Because these instruments use spectroscopy, at each sounding footprint a spectrum is recorded—this means there is a significantly (about 1000×) more data to transfer than what would be required of just an RGB pixel. Changes in surface albedo and viewing angles may affect measurements, and satellites may employ different viewing modes over different locations; these may be accounted for in the algorithms used to convert raw into final measurements. As with other space-based instruments, space debris must be avoided to prevent damage.

Water vapor can dilute other gases in air and thus change the amount of CO2 in a column above the surface of the Earth, so often column-average dry-air mole fractions (XCO2) are reported instead. To calculate this, instruments may also measure O2, which is diluted similarly to other gases, or the algorithms may account for water and surface pressure from other measurements.[15] Clouds may interfere with accurate measurements so platforms may include instruments to measure clouds. Because of measurement imperfections and errors in fitting signals to obtain XCO2, space-based observations may also be compared with ground-based observations such as those from the TCCON.[16]

List of instruments

Instrument/satellitePrimary institution(s)Service datesApproximate usable
daily soundings		Approximate
sounding size		Public dataNotesRefs
HIRS-2/TOVS (NOAA-10)NOAA (U.S.)July 1987–
June 1991		100 × 100 kmNoMeasuring CO2 was not an original mission goal[17]
IMG (ADEOS I)NASDA (Japan)17 August 1996–
June 1997		508 × 8 kmNoFTS system[18]
SCIAMACHY (Envisat)ESA, IUP University of Bremen (Germany)1 March 2002–
May 2012		5,00030 × 60 kmYes[19][20]
AIRS (Aqua)JPL (U.S.)4 May 2002–
ongoing		18,00090 × 90 kmYes[21][22][23]
IASI (MetOp)CNES/EUMETSAT (ESA)19 October 200620-39 km diameterYes (only a few days)[24][25]
GOSATJAXA (Japan)23 January 2009–
ongoing		10,00010.5 km diameterYes[26]First dedicated high precision (<0.3%) mission, also measures CH4[27][28]
OCOJPL (U.S.)24 February 2009100,0001.3 × 2.2 kmN/AFailed to reach orbit
OCO-2JPL (U.S.)2 July 2014–
ongoing		100,0001.3 × 2.2 kmYes[29]High precision (<0.3%)[30]
GHGSat-D (or Claire)GHGSat (Canada)21 June 2016–
ongoing		~2–5 images,
10,000+ pixels each		12 × 12 km,
50 m resolution image		available to selected partners onlyCubeSat and imaging spectrometer[31]
TanSat (or CarbonSat)CAS (China)21 December 2016–
ongoing		100,0001 × 2 kmYes (L1B radiances)[32][33][34]
GAS FTS aboard FY-3DCMA (China)15 Nov 2017–
ongoing[35]		15,00013 km diameterInstrument testing and validation phase[36][37]
GMI (GaoFen-5, (fr))CAS (China)8 May 2018–
ongoing[38]		10.3 km diameterInstrument testing and validation phase[39][40]
GOSAT-2JAXA (Japan)expected 201810,000+9.7 km diameterexpected release in 2018Will also measure CH4 and CO[41]
OCO-3JPL (U.S.)expected 2019100,000<4.5 × 4.5 kmTo be mounted on the ISS[42]
MicroCarbCNES (France)expected 2020~30,0004.5 × 9 kmWill likely also measure CH4[43]
GOSAT-3JAXA (Japan)expected 2022
GeoCARBUniversity of Oklahoma (U.S.)expected 2023~800,0003 × 6 kmFirst CO2-observing geosynchronous satellite, will also measure CH4 and CO[44][45]

There have been other conceptual missions which have undergone initial evaluations but have not been chosen to become a part of space-based observing systems. These include:

  • Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) is a lidar-based mission[46]
  • Geostationary Fourier Transform Spectrometer (GeoFTS)[47]
  • Atmospheric Imaging Mission for Northern regions (AIM-North) would involve a constellation of two satellites focused on polar regions[48]

References

  1. ↑ Schimel, David (November 2007). "Carbon cycle conundrums". Proceedings of the National Academy of Sciences. 104 (47): 18353–18354. Bibcode:2007PNAS..10418353S. doi:10.1073/pnas.0709331104. PMC 2141782.
  2. ↑ Schimel, David; Stephens, Britton B.; Fisher, Joshua B. (January 2015). "Effect of increasing CO2on the terrestrial carbon cycle". Proceedings of the National Academy of Sciences. 112 (2): 436–441. Bibcode:2015PNAS..112..436S. doi:10.1073/pnas.1407302112. PMC 4299228.
  3. ↑ Cox, Peter M.; Pearson, David; Booth, Ben B.; et al. (February 2013). "Sensitivity of tropical carbon to climate change constrained by carbon dioxide variability". Nature. 494 (7437): 341–344. Bibcode:2013Natur.494..341C. doi:10.1038/nature11882.
  4. ↑ Kort, Eric A.; Frankenberg, Christian; Miller, Charles E.; et al. (September 2012). "Space-based observations of megacity carbon dioxide". Geophysical Research Letters. 39 (17). L17806. Bibcode:2012GeoRL..3917806K. doi:10.1029/2012GL052738.
  5. ↑ Hammerling, Dorit M.; Michalak, Anna M.; O'Dell, Christopher; et al. (April 2012). "Global CO2 distributions over land from the Greenhouse Gases Observing Satellite (GOSAT)". Geophysical Research Letters. 39 (8). Bibcode:2012GeoRL..39.8804H. doi:10.1029/2012GL051203.
  6. ↑ Hakkarainen, J.; Ialongo, I.; Tamminen, J. (November 2016). "Direct space-based observations of anthropogenic CO2 emission areas from OCO-2". Geophysical Research Letters. 43 (21): 11, 400–11, 406. Bibcode:2016GeoRL..4311400H. doi:10.1002/2016GL070885.
  7. ↑ Basu, S.; Guerlet, S.; Butz, A.; et al. (September 2013). "Global CO2 fluxes estimated from GOSAT retrievals of total column CO2". Atmospheric Chemistry and Physics. 13 (17): 8695–8717. Bibcode:2013ACP....13.8695B. doi:10.5194/acp-13-8695-2013.
  8. ↑ Deng, F.; Jones, D. B. A.; Henze, D. K.; et al. (April 2014). "Inferring regional sources and sinks of atmospheric CO2 from GOSAT XCO2 data". Atmospheric Chemistry and Physics. 14 (7): 3703–3727. Bibcode:2014ACP....14.3703D. doi:10.5194/acp-14-3703-2014.
  9. ↑ Wunch, D.; Wennberg, P. O.; Messerschmidt, J.; et al. (September 2013). "The covariation of Northern Hemisphere summertime CO2 with surface temperature in boreal regions". Atmospheric Chemistry and Physics. 13 (18): 9447–9459. Bibcode:2013ACP....13.9447W. doi:10.5194/acp-13-9447-2013.
  10. ↑ Keppel-Aleks, G.; Wennberg, P. O.; O'Dell, C. W.; et al. (April 2013). "Towards constraints on fossil fuel emissions from total column carbon dioxide". Atmospheric Chemistry and Physics. 13 (8): 4349–4357. Bibcode:2013ACP....13.4349K. doi:10.5194/acp-13-4349-2013.
  11. ↑ Ross, Adrian N.; Wooster, Martin J.; Boesch, Hartmut; et al. (August 2013). "First satellite measurements of carbon dioxide and methane emission ratios in wildfire plumes". Geophysical Research Letters. 40 (15): 4098–4102. Bibcode:2013GeoRL..40.4098R. doi:10.1002/grl.50733.
  12. ↑ Silva, Sam J.; Arellano, Avelino F.; Worden, Helen M. (September 2013). "Toward anthropogenic combustion emission constraints from space-based analysis of urban CO2/CO sensitivity". Geophysical Research Letters. 40 (18): 4971–4976. Bibcode:2013GeoRL..40.4971S. doi:10.1002/grl.50954.
  13. ↑ Heymann, J.; Reuter, M.; Buchwitz, M.; et al. (February 2017). "CO2 emission of Indonesian fires in 2015 estimated from satellite-derived atmospheric CO2 concentrations". Geophysical Research Letters. Bibcode:2017GeoRL..44.1537H. doi:10.1002/2016GL072042.
  14. ↑ Patra, Prabir Kumar; Crisp, David; Kaiser, Johannes W.; et al. (14 December 2016). Orbiting Carbon Observatory (OCO-2) tracks increase of carbon release to the atmosphere during the 2014-2016 El Niño. 2016 AGU Fall Meeting. 12-16 December 2016. San Francisco, California.
  15. ↑ Wunch, D.; Toon, G. C.; Blavier, J.-F. L.; et al. (May 2011). "The Total Carbon Column Observing Network". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 369 (1943): 2087–2112. Bibcode:2011RSPTA.369.2087W. doi:10.1098/rsta.2010.0240.
  16. ↑ Butz, A.; Guerlet, S.; Hasekamp, O.; et al. (July 2011). "Toward accurate CO2 and CH4 observations from GOSAT". Geophysical Research Letters. 38 (14). L14812. Bibcode:2011GeoRL..3814812B. doi:10.1029/2011GL047888.
  17. ↑ Chédin, A.; Serrar, S.; Scott, N. A.; et al. (September 2003). "First global measurement of midtropospheric CO2 from NOAA polar satellites: Tropical zone". Journal of Geophysical Research. 108 (D18). Bibcode:2003JGRD..108.4581C. doi:10.1029/2003JD003439.
  18. ↑ Kobayashi, Hirokazu; Shimota, Akiro; Kondo, Kayoko; et al. (November 1999). "Development and Evaluation of the Interferometric Monitor for Greenhouse Gases: a High-throughput Fourier-transform Infrared Radiometer for Nadir Earth Observation". Applied Optics. 38 (33): 6801–6807. Bibcode:1999ApOpt..38.6801K. doi:10.1364/AO.38.006801.
  19. ↑ "SCIAMACHY Data Products at IUP/IFE Bremen". IUP Bremen. Retrieved 28 January 2017.
  20. ↑ Buchwitz, M.; de Beek, R.; Burrows, J. P.; et al. (March 2005). "Atmospheric methane and carbon dioxide from SCIAMACHY satellite data: initial comparison with chemistry and transport models". Atmospheric Chemistry and Physics. 5 (4): 941–962. doi:10.5194/acp-5-941-2005.
  21. ↑ "CO2 Documents". AIRS Version 5 Documentation. NASA / Goddard Space Flight Center. 19 November 2015. Retrieved 11 February 2017.
  22. ↑ Olsen, Edward T.; Chahine, Moustafa T.; Chen, Luke L.; et al. (April 2008). "Retrieval of mid-tropospheric CO2 directly from AIRS measurements". Proceedings of the SPIE. 6966. 696613. Bibcode:2008SPIE.6966E..13O. doi:10.1117/12.777920.
  23. ↑ Chahine, M. T.; Chen, Luke; Dimotakis, Paul; et al. (September 2008). "Satellite remote sounding of mid-tropospheric CO2". Geophysical Research Letters. 35 (17). L17807. Bibcode:2008GeoRL..3517807C. doi:10.1029/2008GL035022.
  24. ↑ "IASI Sounding Products". National Oceanic and Atmospheric Administration. Retrieved 22 October 2017.
  25. ↑ Liuzzia, G.; Masielloa, G.; Serioa, C.; et al. (October 2016). "Physical inversion of the full IASI spectra: Assessment of atmospheric parameters retrievals, consistency of spectroscopy and forward modelling". Journal of Quantitative Spectroscopy and Radiative Transfer. 182. Bibcode:2016JQSRT.182..128L. doi:10.1016/j.jqsrt.2016.05.022.
  26. ↑ "GOSAT Data Archive Service (GDAS)". National Institute for Environmental Studies. Retrieved 28 January 2017.
  27. ↑ Kuze, Akihiko; Suto, Hiroshi; Nakajima, Masakatsu; et al. (December 2009). "Thermal and near infrared sensor for carbon observation Fourier-transform spectrometer on the Greenhouse Gases Observing Satellite for greenhouse gases monitoring". Applied Optics. 48 (35). 6716. Bibcode:2009ApOpt..48.6716K. doi:10.1364/AO.48.006716.
  28. ↑ Kuze, Akihiko; Suto, Hiroshi; Shiomi, Kei; et al. (June 2016). "Update on GOSAT TANSO-FTS performance, operations, and data products after more than 6 years in space". Atmospheric Measurement Techniques. 9 (6): 2445–2461. Bibcode:2016AMT.....9.2445K. doi:10.5194/amt-9-2445-2016.
  29. ↑ "CO2 Virtual Science Data Environment". NASA / Jet Propulsion Laboratory. Retrieved 11 February 2017.
  30. ↑ Eldering, Annmarie; O'Dell, Chris W.; Wennberg, Paul O.; et al. (February 2017). "The Orbiting Carbon Observatory-2: First 18 months of science data products". Atmospheric Measurement Techniques Discussions. 10 (2): 549–563. Bibcode:2017AMT....10..549E. doi:10.5194/amt-10-549-2017.
  31. ↑ "GHGSat Global Emissions Monitoring". GHGSat. Retrieved 11 February 2017.
  32. ↑ "FENGYUN Satellite Data Center". National Satellite Meteorological Center. Retrieved 27 October 2017.
  33. ↑ Liu, Yi; Yang, DongXu; Cai, ZhaoNan (May 2013). "A retrieval algorithm for TanSat XCO2 observation: Retrieval experiments using GOSAT data". Chinese Science Bulletin. 58 (13): 1520–1523. Bibcode:2013ChSBu..58.1520L. doi:10.1007/s11434-013-5680-y.
  34. ↑ Liu, Jia (22 December 2016). "China Launches Satellite to Monitor Global Carbon Emissions". Chinese Academy of Sciences. Xinhua. Retrieved 11 February 2017.
  35. ↑ Clark, Stephen (14 November 2017). "Chinese weather satellite launched into polar orbit". Spaceflight Now. Retrieved 11 May 2018.
  36. ↑ "Satellite: FY-3D". WMO Observing Systems Capability Analysis and Review Tool. Retrieved 22 October 2017.
  37. ↑ "China successfully launched FY-3D polar orbiting meteorological satellite". China Meteorological Administration. Retrieved 16 November 2017.
  38. ↑ Barbosa, Rui (8 May 2018). "Chinese weather satellite launched into polar orbit". NASAspaceflight.com. Retrieved 11 May 2018.
  39. ↑ Chen, Liangfu (2016). Mission Overview GaoFen-5 (PDF). CEOS-ACC-12 meeting. 13-15 October 2016. Seoul, Korea.
  40. ↑ Liu, Yi (2017). CO2 Monitoring from Space: TanSat and GF-5/GMI Mission Status (PDF). The 9th GEOSS Asia-Pacific Symposium. 11-13 January 2017. Tokyo, Japan.
  41. ↑ Matsunaga, T.; Maksyutov, S.; Morino, I.; et al. (2016). The Status of NIES GOSAT-2 Project and NIES Satellite Observation Center (PDF). 12th International Workshop on Greenhouse Gas Measurements from Space. 7-9 June 2016. Kyoto, Japan.
  42. ↑ Eldering, Annmarie; Worden, John (October 2016). "OCO-3 Science and Status for CEOS" (PDF). Committee on Earth Observation Satellites.
  43. ↑ Buisson, Francois; Pradines, Didier; Pascal, Veronique; et al. (9 June 2016). An Introduction to MicroCarb, First European Program for CO2 Monitoring (PDF). 12th International Workshop on Greenhouse Gas Measurements from Space. 7-9 June 2016. Kyoto, Japan.
  44. ↑ Polonsky, I. N.; O'Brien, D. M.; Kumer, J. B.; et al. (April 2014). "Performance of a geostationary mission, geoCARB, to measure CO2, CH4 and CO column-averaged concentrations". Atmospheric Measurement Techniques. 7 (4): 959–981. Bibcode:2014AMT.....7..959P. doi:10.5194/amt-7-959-2014.
  45. ↑ Moore, Berrien III (8 June 2017). GeoCARB, Geostationary Carbon Observatory (PDF). 13th International Workshop on Greenhouse Gas Measurements from Space. 6-8 June 2017. Helsinki, Finland.
  46. ↑ Wang, J. S.; Kawa, S. R.; Eluszkiewicz, J.; et al. (December 2014). "A regional CO2 observing system simulation experiment for the ASCENDS satellite mission". Atmospheric Chemistry and Physics. 14 (23): 12897–12914. Bibcode:2014ACP....1412897W. doi:10.5194/acp-14-12897-2014.
  47. ↑ Key, Richard; Sander, Stanley; Eldering, Annmarie; et al. (2012). The Geostationary Fourier Transform Spectrometer. 2012 IEEE Aerospace Conference. 3-10 March 2012. Big Sky, Montana. doi:10.1109/AERO.2012.6187164.
  48. ↑ "AIM-North The Atmospheric Imaging Mission for Northern regions". AIM-North.ca. Retrieved 11 May 2018.

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