Journal article
How well do different tracers constrain the firn diffusivity profile?
CM Trudinger, IG Enting, PJ Rayner, DM Etheridge, C Buizert, M Rubino, PB Krummel, T Blunier
Atmospheric Chemistry and Physics | COPERNICUS GESELLSCHAFT MBH | Published : 2013
Abstract
Firn air transport models are used to interpret measurements of the composition of air in firn and bubbles trapped in ice in order to reconstruct past atmospheric composition. The diffusivity profile in the firn is usually calibrated by comparing modelled and measured concentrations for tracers with known atmospheric history. However, in most cases this is an under-determined inverse problem, often with multiple solutions giving an adequate fit to the data (this is known as equifinality). Here we describe a method to estimate the firn diffusivity profile that allows multiple solutions to be identified, in order to quantify the uncertainty in diffusivity due to equifinality. We then look at h..
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Awarded by Australian Professorial Fellowship
Awarded by Office Of Internatl Science &Engineering; Office Of The Director
Funding Acknowledgements
This work has been undertaken as part of the Australian Climate Change Science Program, funded jointly by the Department of Climate Change and Energy Efficiency, the Bureau of Meteorology and CSIRO. CSIRO's research in this area was also funded by the Centre for Ice and Climate at the University of Copenhagen. The Centre of Excellence of Mathematics and Statistics of Complex Systems (MASCOS) has been funded by the Australian Research Council. I. Enting's fellowship at MASCOS was funded in part by CSIRO. P. Rayner is in receipt of an Australian Professorial Fellowship (DP1096309). C. Buizert was supported by the NOAA Climate and Global Change Fellowship Program, administered by the University Corporation for Atmospheric Research. We would like to thank all those involved in the logistics, drilling, sampling and analysis for the firn air campaigns at DE08-2, South Pole 1995, DSSW20K, South Pole 2001 and NEEM 2008. We thank Patricia Martinerie for useful discussions and sharing atmospheric histories, Jeff Severinghaus for advice on equations for eddy diffusion and Mark Battle for providing data and advice for the South Pole firn sites. We acknowledge Ben Miller (now at CIRES/University of Colorado) for the Cape Grim Air Archive measurements of HCFC-141b used in this work. We thank Jeff Severinghaus and an anonymous reviewer for helpful comments and suggestions.