The Total Carbon Column Observing Network (TCCON) is a global network of instruments that measure the amount of

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has a ...

and other

trace gas Trace gases are gases that are present in small amounts within an environment such as a planet's atmosphere. Trace gases in Earth's atmosphere are gases other than nitrogen (78.1%), oxygen (20.9%), and argon (0.934%) which, in combination, make u ...

es in the

Earth's atmosphere The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...

. The TCCON ( ) began in 2004 with the installation of the first instrument in

Park Falls, Wisconsin Park Falls is a city in Price County, Wisconsin, United States. The population was 2,462 at the 2010 census. Located in the woods of north central Wisconsin, primarily the Chequamegon National Forest, Park Falls is a small community divided by t ...

, USA, and has since grown to 23 operational instruments worldwide, with 7 former sites. The TCCON is designed to investigate several things, including the flow (or

flux Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications to physics. For transport ph ...

) of carbon between the atmosphere, land, and ocean (the so-called

carbon budget A carbon budget is "the maximum amount of cumulative net global anthropogenic carbon dioxide () emissions that would result in limiting global warming to a given level with a given probability, taking into account the effect of other anthropogen ...

carbon cycle The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and Earth's atmosphere, atmosphere of the Earth. Carbon is the main component of biological compounds as well as ...

). This is achieved by measuring the atmospheric mass of carbon (the

airborne fraction The airborne fraction is a scaling factor defined as the ratio of the annual increase in atmospheric to the emissions from human sources.Forster, P, V Ramaswamy, P Artaxo, ''et al.'' (2007) Changes in Atmospheric Constituents and in Radiative Fo ...

). The TCCON measurements have improved the scientific community's understanding of the

,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, . Available from: http://www.agu.org/pubs/crossref/2007/2007GL029742.shtmlChevallier, 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, . Available from: http://www.agu.org/pubs/crossref/201...GL049899.shtml and urban

greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and lar ...

.Verifying Greenhouse Gas Emissions: Methods to Support International Climate Agreements, http://www.nap.edu/catalog/12883.html 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. 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 The TCCON provides the primary measurement validation dataset for the Orbiting Carbon Observatory (OCO-2) mission,NASA.gov
/ref> and has been used to validate other

space-based measurements of carbon dioxide Space-based measurements of carbon dioxide () 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 ...

History

The TCCON was established partly because of modeling errors between mixing efficiency between the PBL and the free

troposphere The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From ...

. 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 ''In situ'' (; often not italicized in English) is a Latin phrase that translates literally to "on site" or "in position." It can mean "locally", "on site", "on the premises", or "in place" to describe where an event takes place and is used in ...

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 San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17th ...

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 The University of Toronto (UToronto or U of T) is a public research university in Toronto, Ontario, Canada, located on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution ...

.TCCON Webpage, https://tccon-wiki.caltech.edu/Sites, accessed February 6, 2016

Measurement technique

The main instrument at each TCCON site is a

Bruker Bruker Corporation is an American manufacturer of scientific instruments for molecular and materials research, as well as for industrial and applied analysis. It is headquartered in Billerica, Massachusetts, and is the publicly traded parent compa ...

IFS 125HR (HR for high resolution, ~0.02 cm⁻¹) or occasionally 120HR

Fourier transform spectrometer Fourier-transform spectroscopy is a measurement technique whereby spectra are collected based on measurements of the coherence of a radiative source, using time-domain or space-domain measurements of the radiation, electromagnetic or not. It ca ...

. 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 Trace gases are gases that are present in small amounts within an environment such as a planet's atmosphere. Trace gases in Earth's atmosphere are gases other than nitrogen (78.1%), oxygen (20.9%), and argon (0.934%) which, in combination, make u ...

primarily in the near

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

region. This

remote sensing Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Earth ...

technique produces a precise and accurate measurement of the

total column The area density (also known as areal density, surface density, superficial density, areic density, mass thickness, column density, or density thickness) of a two-dimensional object is calculated as the mass per unit area. The SI derived unit is ...

abundance of the

. 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).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, . Available from: http://rsta.royalsocietypublishing.o.../2087.full.pdf

Participating sites and Institutions

Current TCCON sites are located in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...

Réunion Réunion (; french: La Réunion, ; previously ''Île Bourbon''; rcf, label= Reunionese Creole, La Rényon) is an island in the Indian Ocean that is an overseas department and region of France. It is located approximately east of the island ...

, and

Ascension Island Ascension Island is an isolated volcanic island, 7°56′ south of the Equator in the South Atlantic Ocean. It is about from the coast of Africa and from the coast of South America. It is governed as part of the British Overseas Territory o ...

. A former site was in

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. 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 The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

JPL The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...

Los Alamos National Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development laboratories of the United States Department of Energy (DOE), located a short distance northwest of Santa Fe, New Mexico, ...

NASA Ames The Ames Research Center (ARC), also known as NASA Ames, is a major NASA research center at Moffett Federal Airfield in California's Silicon Valley. It was founded in 1939 as the second National Advisory Committee for Aeronautics (NACA) laborat ...

, and the

. In Europe some of these include

Karlsruhe Institute of Technology The Karlsruhe Institute of Technology (KIT; german: Karlsruher Institut für Technologie) is a public research university in Karlsruhe, Germany. The institute is a national research center of the Helmholtz Association. KIT was created in 2009 w ...

Max Planck Institute for Biogeochemistry The Max Planck Institute for Biogeochemistry is located in Jena, Germany. It was created in 1997, and moved into new buildings 2002. It is one of 80 institutes in the Max Planck Society (Max Planck Gesellschaft). Departments and research gro ...

University of Bremen The University of Bremen (German: ''Universität Bremen'') is a public university in Bremen, Germany, with approximately 23,500 people from 115 countries. It is one of 11 institutions which were successful in the category "Institutional Strategi ...

, Agencia Estatal de Meteorología,

Royal Belgian Institute for Space Aeronomy Royal may refer to: People * Royal (name), a list of people with either the surname or given name * A member of a royal family Places United States * Royal, Arkansas, an unincorporated community * Royal, Illinois, a village * Royal, Iowa, a ci ...

Finnish Meteorological Institute The Finnish Meteorological Institute (FMI; fi, Ilmatieteen laitos; sv, Meteorologiska institutet) is the government agency responsible for gathering and reporting weather data and forecasts in Finland. It is a part of the Ministry of Transport ...

, and

Pierre and Marie Curie University Pierre and Marie Curie University (french: link=no, Université Pierre-et-Marie-Curie, UPMC), also known as Paris 6, was a public university, public research university in Paris, France, from 1971 to 2017. The university was located on the Jussi ...

. In the western Pacific some of these include

University of Wollongong The University of Wollongong (abbreviated as UOW) is an Australian public research university located in the coastal city of Wollongong, New South Wales, approximately 80 kilometres south of Sydney. As of 2017, the university had an enrolment of ...

National Institute of Water and Atmospheric Research The National Institute of Water and Atmospheric Research or NIWA ( mi, Taihoro Nukurangi), is a Crown Research Institute of New Zealand. Established in 1992, NIWA conducts research across a broad range of disciplines in the environmental scien ...

National Institute for Environmental Studies The National Institute for Environmental Studies (''NIES'':国立環境研究所, Kokuritsu-Kankyō kenkyūsho) was established in 1974 as a focal point for environmental research in Japan. In 2001 it became an Independent Administrative Institut ...

JAXA The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into orb ...

, 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. It includes the I2S (interferogram to spectrum)

FFT A fast Fourier transform (FFT) is an algorithm that computes the discrete Fourier transform (DFT) of a sequence, or its inverse (IDFT). Fourier analysis converts a signal from its original domain (often time or space) to a representation in the ...

, and GFIT spectral fitting subroutines. GFIT is also the fitting algorithm that was used for ATMOS which flew on the

Space Shuttle The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...

, and is used for spectral fitting of spectra obtained by a balloon borne spectrometer.

Map

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

with the Caltech Library and are available from http://tccondata.org. Data are made publicly available provided the data license is followed. 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 The South Coast Air Basin—SCAB (or SoCAB) is one of several regional air basin areas designated by the state of California, for the purpose of air quality management and air pollution control in Southern California. The SCAB district was created ...

containing

Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...

using TCCON measurements and the

CARB The California Air Resources Board (CARB or ARB) is the "clean air agency" of the government of California. Established in 1967 when then-governor Ronald Reagan signed the Mulford-Carrell Act, combining the Bureau of Air Sanitation and the Motor ...

inventory.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. * Characterization of biosphere fluxes in the Southern Hemisphere * Evaluation of the seasonal exchange of CO₂ between the biosphere and the atmosphere * Numerous satellite validation projects 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. * Validation projects involving comparison of CO₂ and CH₄ measured by TCCON with that measured by lower-resolution instruments * Covariation between surface temperature and CO₂ in boreal regions * Distinguishing between which of two power plants (~2000 MW each) plumes of polluted air came from in conjunction with a Pandora NO₂ spectrometerRodica 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

Satellite support

The satellite missions supported by the TCCON include the Greenhouse Gases Observing Satellite (GOSAT),Crisp, D. et al.: The ACOS XCO2 retrieval algorithm, Part 2: Global XCO2 data characterization, Atmos. Meas. Tech. Discuss., 5, 1-60, , 2012, http://www.atmos-meas-tech-discuss.net/5/1/2012/amtd-5-1-2012.htmlButz, A. et al. (2011), Toward accurate CO2 and CH4 observations from GOSAT, Geophysical Research Letters, 38(14), 2-7, , http://www.agu.org/pubs/crossref/2011/2011GL047888.shtmlMorino, 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, , http://www.atmos-meas-tech.net/4/1061/2011/

SCIAMACHY SCIAMACHY (SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY; Greek: σκιάμάχη: analogously: "Fighting shadows") was one of ten instruments aboard of ESA's ENVIronmental SATellite, ENVISAT. It was a satellite spectrome ...

,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, , http://www.atmos-chem-phys.net/6/2727/2006/ and the Orbiting Carbon Observatory-2 (OCO-2).

References

External links

*{{Commons category-inline, TCCON Atmospheric sciences