References

ACPD

Atmospheric Chemistry and Physics Discussions

ACPD

1680-7375

Copernicus GmbH

Göttingen, Germany

10.5194/acpd-11-30627-2011

The isotopic record of Northern Hemisphere atmospheric carbon monoxide since 1950, implications for the CO budget

Wang

¹ Chappellaz

² Martinerie

² Park

¹ ⁷ Petrenko

³ ⁸ Witrant

⁴ Blunier

⁵ Brenninkmeijer

C. A. M.

⁶ Mak

J. E.

Institute for Terrestrial and Planetary Atmospheres/School of Marine and Atmospheric Sciences, State University of New York at Stony Brook, Stony Brook, NY 11794, USA

UJF – Grenoble 1/CNRS, Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE) UMR 5183, Grenoble, 38041, France

Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA

Grenoble Image Parole Signal Automatique (GIPSA-lab), Université Joseph Fourier/CNRS, BP 46, 38 402 Saint Martin d'Hères, France

Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30, 2100 Copenhagen Ø, Denmark

Max Planck Institute for Chemistry, 55128 Mainz, Germany

now at: Division of Polar Climate Research, Korea Polar Research Institute, Incheon, South Korea

now at: Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY, USA

15 11 2011

11 11 30627 30663

This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

This article is available from http://www.atmos-chem-phys-discuss.net/11/30627/2011/acpd-11-30627-2011.html

The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/11/30627/2011/acpd-11-30627-2011.pdf

We present a 60-yr record of atmospheric CO concentration and stable isotopic ratios at high northern latitude based on firn air samples collected in the frame of the North Greenland Eemian Ice Drilling (NEEM) project. Concentration, δ13C, and δ18O of CO from trapped gases in the firn were measured by gas chromatography coupled with isotope ratio mass spectrometry (gc-IRMS). Using models of trace gas transport in firn, the long-term trend of atmospheric CO and its stable isotopic composition at high northern latitudes since the 1950s were reconstructed. Our best firn air scenarios suggest that δ13C decreased slightly from −25.8&permil; in 1950 to −26.4&permil; in 2000, then dropped to −27.2&permil; in 2008. δ18O decreased more regularly from 9.8&permil; in 1950 to 7.1&permil; in 2008. The best firn air scenarios also suggest that CO concentration increased gradually from 1950 and peaked likely in the late-1970s, followed by a gradual decrease by present day (Petrenko et al., 2011). An isotope mass balance model is applied to quantify the temporal evolution of CO source partitioning able to explain the combined mixing ratio and isotopic ratio changes. It suggests that a slight increase followed by a large reduction in CO derived from fossil fuel combustion occurred since 1950. The increase of CO concentration from 1950 to the mid-1970s is the result of a combined increase of multiple sources. The reduction of CO emission from fossil fuel combustion after the mid-1970s is the most plausible mechanism for the drop of CO concentration during this time. The mitigation policy for CO emission from vehicle exhaust such as application of catalytic converters and the growth of diesel engine vehicles market share are the main expected reasons for the CO source strength change from fossil fuel combustion.

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