Modern Records of Atmospheric Nitrous Oxide (N2O) and a 2000-year Ice-core Record from Law Dome, Antarctica
This page provides an introduction and links to records of atmospheric nitrous oxide (N2O) over the last 2000 years, emphasizing large data bases each representing currently active stations. Records in recent decades (time period depending on location) have been obtained from samples of ambient-air at remote locations, which represent changing global atmospheric conditions rather than influences of local sources. The longer (2000-year) record is from the Law Dome ice core in Antarctica. The ice-core record has been merged with modern annual data from Cape Grim, Tasmania to provide a 2000-year time series of annual values. A spline function has been fit to the data to provide a continuous time series of annual values. Longer-term series from Antarctic ice cores, back to 800,000 years before present, are available at http://cdiac.ornl.gov/ice_core_no.html.
The following organizations have current data from multiple sites.
- The Advanced Global Atmospheric Gases Experiment (AGAGE) and its European Counterpart, the System for Observation of halogenated Greenhouse gases in Europe (SOGE).
- The Commonwealth Scientific and Industrial Research Organization (CSIRO) of Australia. Particularly David Etheridge who suggested the law dome data be included, and who provided it.
- The Global Monitoring Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration (NOAA).
- CDIAC maintains records for additional individual locations covering limited time periods.
Period of Record
13 C.E. - current
For locations of modern CH4 sampling stations for AGAGE/SOGE and CSIRO: http://cdiac.ornl.gov/images/maps_m-ch4-n2o.jpg. For NOAA locations: http://www.esrl.noaa.gov/gmd/dv/iadv/ and click on a location to see which gases are measured there.
A map of Antarctic stations is given below, along with a detailed map of the Law Dome area.
Maps of Antarctica showing locations of the stations listed below; elevations are given in meters above sea level (masl). Law Dome (66°44'S, 112°50'E, 1390 masl), Dome C (75°06'S, 123°24'E, 3233 masl), Taylor Dome 77°48'S, 158°43'E, 2365 masl), Vostok (78°28'S, 106°52'E, 3500 masl), Dome A, (80°22'S, 77°22'°E, 4084 masl), the South Pole station (90°S, 2810 masl), and Siple Station (75°55'S, 83°55'W, 1054 masl.) The detailed map on the right is adapted from Etheridge et al. (1996), adapted, in turn, from Hamley et al. (1986).
- AGAGE: http://agage.eas.gatech.edu/images/Data_figures/gcmd_month/n2o_monS5.pdf
- CSIRO: http://www.cmar.csiro.au/research/capegrim_graphs.html. for more detailed N2O graphics at Cape Grim, Tasmania, go to http://www.csiro.au/greenhouse-gases/. Immediately below the graph on the left hand side you will find a selection bar, select nitrous oxide.
- NOAA: http://www.esrl.noaa.gov/gmd/dv/iadv/. This link gets to the visualization page for all gases, move mouse over any point on the map to get its 3-letter station code (e.g. SPO is the South Pole). N2O is listed under Halocarbons and Trace Gases.
- CDIAC: 50-year moving averages of spline-function values of CH4, CO2, N2O, are shown at http://cdiac.ornl.gov/images/three_gases_historical.jpg.
- AGAGE: http://cdiac.ornl.gov/ndps/alegage.html.
- CSIRO: CSIRO_gaslab_data_Aug2011.zip.
- NOAA: http://www.esrl.noaa.gov/gmd/dv/data/. Select greenhouse gases from the first column; then select nitrous oxide from the second column. Information about station codes is at: http://www.esrl.noaa.gov/gmd/dv/site/site_table2.html.
- LAW DOME: A complete set of all Law Dome records, including the 2000-year time series of ice-core data merged with the modern cape-grim record, is available at: http://www.ncdc.noaa.gov/paleo/icecore/antarctica/law/law_data.html.
- Some Surface Water and Atmospheric Carbon Dioxide and Nitrous Oxide Observations by Shipboard Automated Gas Chromatography from Expeditions Between 1977 and 1990 are available at: http://cdiac.ornl.gov/oceans/ndp_044/
Samples are analyzed using gas chromatography followed electron capture in which available electrons are selectively captured in proportion to the amount of substance being analyzed, thereby creating an electrical signal which can be measured. More detail on sampling, preparation, and measurement by NOAA is given by Hall et al. (2007) and for CSIRO in the readme file for N2O available from the data link given above. AGAGE data were obtained in a generally similar fashion; details on the AGAGE air sampling, preparation, and measurement process are found in Prinn et al. (2000), and at this web page. Information about the CSIRO sampling program is given in Francey (2003). Current information on reference scales and other details of measurement may be found at the following links:
- AGAGE: http://agage.eas.gatech.edu/data_archive/agage/gc-md/readme.scale
- CSIRO: See the (pdf or doc) readme file for N2O at CSIRO_gaslab_data_Aug2011.zip
- NOAA: http://www.esrl.noaa.gov/gmd/hats/insitu/insitu.html.
Law Dome Ice Core Data
Air was extracted from the ice core samples using a dry extraction "cheese grater" and cryogenic trapping technique developed by Etheridge et al. (1996) with only minor alterations (MacFarling Meure, 2004). The trapped air samples were analyzed by gas chromatography and the trace gas concentrations are reported on the calibration scales maintained by CSIRO GASLAB (Francey et al., 2003).
The ice cores were dated by counting the annual layers of oxygen isotope ratio (d18O in H2O), of ice electroconductivity measurements (ECM) and of hydrogen peroxide (H2O2). For these three parameters, each core displayed clear, well-preserved seasonal cycles allowing a dating accuracy of about 5 years, and exact dating in recent centuries where material from known volcanoes is present. (ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/law/law2006.txt). The Law Dome data were merged with modern deseasonalised flask and in situ records for CO2 at Cape Grim, Tasmania, and a spline function was fit to the result to provide a continuous time series of annual values extending back approximately 2000 years before the present.
For more details about methodology see: http://cdiac.ornl.gov/trends/co2/law_dome_methods.html.
Nitrous oxide began to increase from a preindustrial value of around 260-270 parts per billion (ppb) during the first part of the 20th Century. (see this figure) A steady increase from about 300 ppb to 325 ppb occurred from 1980 to 2010. (see this graph)
Northern Hemisphere amounts are slightly greater than in the Southern Hemisphere, suggesting the Northern Hemisphere is the net source of the overall increase. Increased use of nitrogen fertilizers and subsequent decomposition by denitrifying bacteria is believed to contribute most to the recent increases in N2O. Nitrous oxide also arises from fossil-fuel combustion and nitric acid production.
References to Ice-Core Data
The Law Dome record consists of ice-core data, firn data, and atmospheric samples at Cape Grim Tasmania. Newer results which fill in gaps, double the length of record from approximately 1000 years to 2000 years, and include N2O, were published and explained in detail in MacFarling Meure 2004 and MacFarling Meure et al. 2006.
- Etheridge, D.M., G.I. Pearman and F. de Silva. 1988. Atmospheric trace-gas variations as revealed by air trapped in an ice core from Law Dome, Antarctica. Ann. Glaciol. 10, 28-33.
- Etheridge, D.M., L.P. Steele, R.L. Langenfelds, R.J. Francey, J.-M. Barnola and V.I. Morgan. 1996. Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn. Journal of Geophysical Research 101, 4115-4128.
- Hamley. T.C., V.I. Morgan, R.J. Thwaites, and X.Q Gao. 1986. An ice-core drilling site at Law Dome summit. Wilkes Land, Antarctica, Research Note 37, Australian Antarctic Research Expedition, Tasmania.
- MacFarling Meure, C. 2004. The natural and anthropogenic variations of carbon dioxide, methane and nitrous oxide during the Holocene from ice core analysis. PhD thesis, University of Melbourne.
- MacFarling Meure, C., D. Etheridge, C. Trudinger, P. Steele, R. Langenfelds, T. van Ommen, A. Smith and J. Elkins. 2006. The Law Dome CO2, CH4 and N2O Ice Core Records Extended to 2000 years BP. Geophysical Research Letters 33, 14, L14810 10.1029/2006GL026152.
- Morgan, V.I., C.W. Wookey, J. Li, T.D. van Ommen, W. Skinner and M.F. Fitzpatrick. 1997. Site information and initial results from deep ice drilling on Law Dome. J. Glaciol. 43, 3-10.
- Trudinger, C.M., I.G. Enting, D.M. Etheridge, R.J. Francey, V.A. Levchenko, et al. 1997. Modeling air movement and bubble trapping in firn. Journal of Geophysical Research 102, (D6) 6747-6763.
References to the Cape Grim (Modern Instrumental) Record
- Francey, R. J., L.P. Steele, D.A. Spencer, R.L. Langenfelds, R.M. Law, et al. 2003. The CSIRO measurement of greenhouse gases in the global atmosphere, in Baseline Atmospheric Program (Australia), 1999–2000, edited by N. W. Tindale, N. Derek and P. J. Fraser, Bureau of Meteorology and CSIRO Atmospheric Research, Melbourne, Australia (pp. 42-53).
- Langenfelds, R.L., P.J. Fraser, R.J. Francey, L.P. Steele, L.W. Porter and C.E. Allison. 1996. The Cape Grim air archive: The first seventeen years, 1978-1995, In: Baseline Atmospheric Program (Australia) 1994-1995. edited by Francey, R.J., A.L. Dick, and N. Derek, Bureau of Meteorology and CSIRO Division of Atmospheric Research, Melbourne, Australia. (pp. 53-70).
- Langenfelds, R.L., L.P. Steele, M.V. Van der Schoot, L.N. Cooper, D.A. Spencer and P.B. Krummel. 2004. Atmospheric methane, carbon dioxide, hydrogen, carbon monoxide and nitrous oxide from Cape Grim flask air samples analysed by gas chromatography. In: Baseline Atmospheric Program Australia. 2001-2002, edited by J.M. Cainey, N. Derek, and P.B. Krummel. Melbourne: Bureau of Meteorology and CSIRO Atmospheric Research. (pp. 46-47).
- Langenfelds, R.L., P.J. Fraser, L.P. Steele and L.W. Porter. 2004. Archiving of Cape Grim Air. In: Baseline Atmospheric Program Australia. 2001-2002, edited by J.M. Cainey, N. Derek and P.B. Krummel. Melbourne: Bureau of Meteorology and CSIRO Atmospheric Research. (p. 48).
- Hall, B. D., G. S. Dutton and J. W. Elkins. 2007. The NOAA nitrous oxide standard scale for atmospheric observations, Journal of Geophysical Research-Atmospheres 112, 10.1029/2006JD007954.
- Prinn, R.G., R.F. Weiss, P.J. Fraser, P.G. Simmonds, D.M. Cunnold, F.N. Alyea, S. O'Doherty, P. Salameh, B.R. Miller, J. Huang, R.H.J. Wang, D.E. Hartley, C. Harth, L.P. Steele, G. Sturrock, P.M. Midgley, and A. McCulloch. 2000. A History of Chemically and Radiatively Important Gases in Air deduced from ALE/GAGE/AGAGE, J. of Geophys. Res.-Atmospheres 105 (D14), 17,751-17,792.
- Prinn, R. G., D.M. Cunnold, R. Rasmussen, P.G. Simmonds, F.N. Alyea, A. Crawford, P.J. Fraser, and R. Rosen, Atmospheric emissions and trends of nitrous oxide deduced from ten years of ALE-GAGE data, J. Geophys. Res. 95, 18369-18385, 1990.
Citing This Material
AGAGE: The general reference for AGAGE data is: Prinn et al. 2000; for N2O , see also Prinn et al. 1990. Both references are given above.
CSIRO: CSIRO requests that use of these data in any paper or presentation be accompanied by acknowledgement of the source of the data (CSIRO Marine and Atmospheric Research GASLAB) and that the version of the data (as specified by release date) be explicitly stated. For additional references to cite, please consult the readme file for N2O in the list of files found at ftp://gaspublic:email@example.com/pub/data/gaslab/.
NOAA: Citations for NOAA/ESRL data are given in the beginning material in each data file (scroll down to Data Use Policy. For flask data see ftp://ftp.cmdl.noaa.gov/hats/n2o/. For in-situ data see: ftp://ftp.cmdl.noaa.gov/hats/n2o/insituGCs/.
LAW DOME ICE CORE DATA For data including the Law dome ice-core records alone or merged with the Cape Grim data, cite:
Etheridge, D.M., et al. 2010. Law Dome Ice Core 2000-Year CO2, CH4, and N2O Data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2010-070. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.
We recommend also citing: MacFarling-Meure, et al. 2006 and, Etheridge 1996 from the references above in any published work.
If accessing the data from this site: please also cite: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy.
If citing material from this page only, cite as: Modern Records of Atmospheric Nitrous Oxide (N2O) and a 2000-year Ice-core Record from Law Dome Ice Cores in Antarctica, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy. http://cdiac.ornl.gov/modern_no.html