Evidence for a CO increase in the SH during the 20th century based on firn air samples from Berkner Island, Antarctica S. S. Assonov1, C. A. M. Brenninkmeijer1, P. Jöckel1, R. Mulvaney2, S. Bernard3, and J. Chappellaz3 1Max Planck Institute for Chemistry, PO 3060, 55020 Mainz, Germany 2British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK 3Laboratoire de Glaciologie et Géophysique de l'Environnement, 54 rue Molière, Domaine Universitaire, BP 96, 38402 St. Martin d'Hères Cedex, France
Abstract. Trends of carbon monoxide (CO) for the past 100 years are reported as
derived from Antarctic firn drilling expeditions. Only one of 3 campaigns
provided high quality results. The trend was reconstructed using a firn air
model in the forward mode to constrain age distributions and assuming the CO
increase to be proportional to its major source, namely CH4. The
results suggest that CO has increased by ~38%, from 38±7 to
52.5±1.5 ppbv over a period of roughly 100 years. The concentrations
are on the volumetric scale which corresponds to ~1.08 of the scale
used by NOAA/CMDL. The estimated CO increase is somewhat larger than what is
estimated from the CO budget estimations and the CH4 growth alone. The
most likely explanation might be an increase in biomass burning emissions.
Using CH3Cl as another proxy produces a very similar reconstruction.
Citation: Assonov, S. S., Brenninkmeijer, C. A. M., Jöckel, P., Mulvaney, R., Bernard, S., and Chappellaz, J.: Evidence for a CO increase in the SH during the 20th century based on firn air samples from Berkner Island, Antarctica, Atmos. Chem. Phys., 7, 295-308, doi:10.5194/acp-7-295-2007, 2007.