Article
 

Gas transport in firn: multiple-tracer characterisation and model intercomparison for NEEM, Northern Greenland

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/articles/r781wm771

Descriptions

Attribute NameValues
Creator
Abstract
  • Air was sampled from the porous firn layer at the NEEM site in Northern Greenland. We use an ensemble of ten reference tracers of known atmospheric history to characterise the transport properties of the site. By analysing uncertainties in both data and the reference gas atmospheric histories, we can objectively assign weights to each of the gases used for the depth-diffusivity reconstruction. We define an objective root mean square criterion that is minimised in the model tuning procedure. Each tracer constrains the firn profile differently through its unique atmospheric history and free air diffusivity, making our multiple-tracer characterisation method a clear improvement over the commonly used single-tracer tuning. Six firn air transport models are tuned to the NEEM site; all models successfully reproduce the data within a 1σ Gaussian distribution. A comparison between two replicate boreholes drilled 64 m apart shows differences in measured mixing ratio profiles that exceed the experimental error. We find evidence that diffusivity does not vanish completely in the lock-in zone, as is commonly assumed. The ice age- gas age difference (Δage) at the firn-ice transition is calculated to be 182[superscript +3 over subscript −9] yr. We further present the first intercomparison study of firn air models, where we introduce diagnostic scenarios designed to probe specific aspects of the model physics. Our results show that there are major differences in the way the models handle advective transport. Furthermore, diffusive fractionation of isotopes in the firn is poorly constrained by the models, which has consequences for attempts to reconstruct the isotopic composition of trace gases back in time using firn air and ice core records.
License
Resource Type
DOI
Date Available
Date Issued
Citation
  • Buizert, C., Martinerie, P., Petrenko, V. V., Severinghaus, J. P., Trudinger, C. M., Witrant, E., Rosen, J. L., Orsi, A. J., Rubino, M., Etheridge, D. M., Steele, L. P., Hogan, C., Laube, J. C., Sturges, W. T., Levchenko, V. A., Smith, A. M., Levin, I., Conway, T. J., Dlugokencky, E. J., Lang, P. M., Kawamura, K., Jenk, T. M., White, J. W. C., Sowers, T., Schwander, J., and Blunier, T.: Gas transport in firn: multiple-tracer characterisation and model intercomparison for NEEM, Northern Greenland, Atmospheric Chemistry and Physics, 12, 4259-4277, doi:10.5194/acp-12-4259-2012, 2012.
Journal Title
Journal Volume
  • 12
Academic Affiliation
Rights Statement
Funding Statement (additional comments about funding)
  • NEEM is directed and organised by the Center for Ice and Climate at the Niels Bohr Institute and US NSF, Office of Polar Programs. It is supported by funding agencies and institutions in Belgium (FNRS-CFB and FWO), Canada (GSC), China (CAS), Denmark (FIST), France (IPEV, CNRS/INSU, CEA and ANR), Germany (AWI), Iceland (RannIs), Japan (NIPR), Korea (KOPRI), The Netherlands (NWO/ALW), Sweden (VR), Switzerland (SNF), United Kingdom (NERC) and the USA (US NSF, Office of Polar Programs). C. Buizert would like to thank Bruce Vaughn (INSTAAR, University of Colorado) for his hospitality and support; V. V. Petrenko has been supported by the NOAA Postdoctoral Fellowship in Climate and Global Change and NSF grants 0632222 and 0806387 (White); A. J. Orsi and J. P. Severinghaus were supported by NSF 0806377; UEA acknowledges NERC for awards NE/F021194/1, NE/F015585/1 and a PhD Studentship (Hogan); the CSIRO contributions to this work were partly supported by the Australian Climate Change Science Program, funded jointly by the Department of Climate Change and Energy Efficiency, the Bureau of Meteorology and CSIRO; the French contribution to this study was further supported by CNRS through INSIS/PEPS-automatique and INSU/LEFE programs.
Publisher
Language
Replaces

Relationships

Parents:

This work has no parents.

Items

Thumbnail Title Date Uploaded Visibility Actions
file details RosenJuliaCEOASGasTransportFirn.pdf 12/06/2017 Public
file details RosenJuliaCEOASGasTransportFirn_Corrigendum.pdf 12/06/2017 Public