Firn Record of Trace Gases Relevant to Atmospheric Chemical Change over 100 yrs (FIRETRACC/100)

There have been dramatic changes in the chemistry of the troposphere over the period of rapid industrialisation during the 20th century. There is evidence that tropospheric ozone has doubled in the Northern Hemisphere in this time, and modelling studies have suggested significant changes in the ability of the atmosphere to remove pollutants (the `oxidising capacity'). Direct measurements of photooxidant chemistry have, however, only been made in recent years, whilst measurements of the trace gases which drive this chemistry extend back only to the late 1970s.

This project aims to use "firn air" - air trapped in deep polar snow - to examine the record of trace gases in both the Northern and Southern hemispheres over the last 80 to 100 years. Unlike ice cores, firn extraction yields large volumes (tens of litres) of air for analysis. This allows samples to be circulated between laboratories for repeated analysis of different suites of trace gases at ultra-trace levels. This will enable a detailed picture of the atmospheric composition to be built up in air of different ages. Extensive modelling studies will then be conducted to determine the trends of short-lived reactive species such as ozone, hydroxyl radical, peroxide, formaldehyde, and reactive oxides of nitrogen. Hence we will determine the extent of human impact on the trace gas composition and photooxidant chemistry of the troposphere.

In summary, the objectives of FIRETRACC/100 are as follows:

• To determine the global trends of trace gases relevant to troposphericchemistry over the 20th century. These will include CO, the isotopiccomposition of CO, hydrocarbons, alkyl nitrates, numerous OH-reactivehalocarbons (such as methyl chloride, methyl chloroform, methyl bromide,hydrochlofluorocarbons, etc.), and sulphur gases (COS, CS2, etc.). Trends of longer lived gases will also be determined for dating purposes (CO2, CFCs,SF6, perfluorocarbons, etc.)
• Determine the evolution of inter-hemispheric ratios of OH-sensitive species to constrain modelled global OH fields
• Examine ratios of parent hydrocarbons to alkyl nitrates to place constraints on NOX fields in models
• Elucidate the sources of CO from isotopic studies and use to deconvolute CO/methane coupling in models
• Reconstruct the history of ozone, OH and tropospheric oxidising capacity over the past 100 years using full chemistry 2-D models
• Determine the influence of 20th century industrialisation on the gas phase composition and chemistry of the lower atmosphere

The data consists of ‘primary’ data comprising simple concentration versus depth profiles, and for selected gases also ‘secondary’ data comprising reconstructed historical trends. The firn diffusion model, used in the model reconstruction, is also available through this site.

The FIRETRACC project was an EU funded (Project reference ENV4970406). The FIRETRACC Scientific Co-ordinator was Dr William Sturges at the University of East Anglia, UK. Other contractors were the NERC British Antarctic Survey (BAS - UK), the Centre National de la Recherche Scientifique (CNRS - France), University of Bern (Switzerland) and the Max-Planck Institute (Germany).

All FIRETRACC data holdings at this site are now publicly available and all data directories can be viewed at any time using the Get Data facility.

All data files and their associated paths can be found in the FIRETRACC Data Directory. Potential users are strongly advised to contact the data provider before making use of any data. The data provider's name and e-mail can be found in the data file header. In case of any queries or difficulties in contacting data providers or using data, please contact the FIRETRACC Scientific Co-ordinator Dr William Sturges . If you need help in downloading the data via the Web or by anonymous FTP, please refer to the Help section.

The data files are in NASA-Ames data format. This format simplifies exchange of data between different computers. All files are written as ASCII and consist of a single header followed by one or more tables of data. A document outlines the File format and naming convention.

The BADC has produced a Help file which contains background information about the FIRETRACC project, i.e. firn air capture procedure, locations of measurements, scientific description of the project.

A list of publications is available.

More information of FIRETRACC can be found at:

• The European Commission Environment and Climate Programme (4th Framework)

More information on the project participants and their institutes can be found at:

• The School of Environmental Sciences, University of East Anglia
• The British Antarctic Survey

Public FIRETRACC data will also be made available through:

• The CNRS Laboratoire de Glaciologie et Geophysique de l'environnement, France
• The University of Bern, Switzerland
• The Max Planck Institute for Chemistry, Germany

Other links of interest:

• Carbon Dioxide Information Analysis Center
• World Data Center for Glaciology

Atlas, E.; Barnola, J-M.; Brenninmeijer, C.; Mulvaney, R.; Schwander, J.; Sturges, W.; Penkett, M.; Penkett, S.; Chappellaz, J.; Jouzel, J. Firn Record of Trace Gases Relevant to Atmospheric Chemical Change over 100 yrs (FIRETRACC/100), [Internet]. NCAS British Atmospheric Data Centre, 2006-, Date of citation. Available from http://badc.nerc.ac.uk/view/badc.nerc.ac.uk__ATOM__dataent_FIRETRACC .

Cited in:

• CITATION: Arnaud, L., Barnola, J. M. and Duval, P.: Physical modeling of the densification of snow/firn and ice in the upper part of polar ice sheets, In Physics of Ice Core Records, T. Hondoh, Ed., Hokkaido University Press, Sapporo, 285-305, 2000.
• CITATION: Assonov, S. S. and Brenninkmeijer, C. A. M.: On the O-17 correction for CO2 mass spectrometric isotopic analysis. Rapid Communications in Mass Spectrometry, 17(10), 1007-1016, 2003.
• CITATION: Assonov, S. S. and Brenninkmeijer C. A. M.: A redetermination of absolute values for R-17(VPDB-CO2) and R- 17(VSMOW). Rapid Communications in Mass Spectrometry, 17(10): 1017-1029, 2003.
• CITATION: Beyerle, U., Leuenberger, M., Schwander, J., and Kipfer, R.,: Noble gas evidence for gas fractionation in firn. Geochimica et Cosmochimica Acta, 67(18): A38-A38, 2003.
• CITATION: Braunlich, M., Aballanin, O., Marik, T., Jockel, P., Brenninkmeijer, C. A. M., Chappellaz, J., Barnola, J. M., Mulvaney, R., Sturges, W.T.,: Changes in the global atmospheric methane budget over the last decades inferred from C-13 and D isotopic analysis of Antarctic firn air. J. Geophys. Res., 106 (D17): 20465-20481, 2001.
• CITATION: Fabre, A., Barnola, J. M., Arnaud, L., and Chappellaz, J.: Determination of gas diffusivity in polar firn: comparison between experimental measurements and inverse modelling. Geophys. Res. Lttr, 27 (4), 557-560, 2000.
• CITATION: Henderson, L, Clark, I. D., Chappellaz, J., Fisher, D., Koerner, R., Worthy, D. E. J., Kotzer, T. and Norman, A-L., CO2 isotopes as tracers of firn air diffusion and age in an Arctic glacier with summer melting. Submitted to J. Geophys. Res., 2004.

If you have queries about these pages or about obtaining the FIRETRACC data from the BADC then you should contact BADC Support. Your query should be answered within one working day. When follow-up work is required, the BADC support will carry out the work as quickly and efficiently as possible, and in any case, the user will be kept informed of progress.

For queries about the FIRETRACC programme please contact the project Co-ordinator, Dr William Sturges. The Principal Investigators are:

• Dr William Sturges, (University of East Anglia, Norwich, UK)
• Secretary; Marigold Penkett
• Prof. Stuart A. Penkett (University of East Anglia, Norwich, UK)
• Dr. Rob Mulvaney (British Antarctic Survey, Cambridge, UK)
• Dr. Jerome Chappellaz (CNRS Laboratoire de Glaciologie et Geophysique de l'Environnement, France)
• Dr Jakob Schwander (University of Berne, Switzerland)
• Dr. Carl Brenninmeijer (Max Planck Institute for Chemistry, Mainz, Germany)
• Dr. Jean Jouzel (CNRS Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France)