Observing and modeling the influence of layering on bubble trapping in polar firn

Logan E. Mitchell, Christo Buizert, Edward J. Brook, Daniel J. Breton, John Fegyveresi, Daniel Baggenstos, Anais Orsi, Jeffrey Severinghaus, Richard B. Alley, Mary Albert, Rachael H. Rhodes, Joseph R. McConnell, Michael Sigl, Olivia Maselli, Stephanie Gregory, Jinho Ahn

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Interpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn. Much work has been done to understand the processes affecting air transport in the open pores of the firn, but a paucity of data from air trapped in bubbles in the firn-ice transition region has limited the ability to constrain the effect of bubble closure processes. Here we present high-resolution measurements of firn density, methane concentrations, nitrogen isotopes, and total air content that show layering in the firn-ice transition region at the West Antarctic Ice Sheet (WAIS) Divide ice core site. Using the notion that bubble trapping is a stochastic process, we derive a new parameterization for closed porosity that incorporates the effects of layering in a steady state firn modeling approach. We include the process of bubble trapping into an open-porosity firn air transport model and obtain a good fit to the firn core data. We find that layering broadens the depth range over which bubbles are trapped, widens the modeled gas age distribution of air in closed bubbles, reduces the mean gas age of air in closed bubbles, and introduces stratigraphic irregularities in the gas age scale that have a peak-to-peak variability of ~10 years at WAIS Divide. For a more complete understanding of gas occlusion and its impact on ice core records, we suggest that this experiment be repeated at sites climatically different from WAIS Divide, for example, on the East Antarctic plateau.

Original languageEnglish (US)
Pages (from-to)2558-2574
Number of pages17
JournalJournal of Geophysical Research
Volume120
Issue number6
DOIs
StatePublished - Jan 1 2015

Fingerprint

firn
Ice
bubbles
trapping
bubble
ice
Gases
modeling
gases
air
Air
ice core
ice sheet
air transportation
porosity
gas
Nitrogen Isotopes
Porosity
nitrogen isotopes
stochastic processes

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

Cite this

Mitchell, L. E., Buizert, C., Brook, E. J., Breton, D. J., Fegyveresi, J., Baggenstos, D., ... Ahn, J. (2015). Observing and modeling the influence of layering on bubble trapping in polar firn. Journal of Geophysical Research, 120(6), 2558-2574. https://doi.org/10.1002/2014JD022766
Mitchell, Logan E. ; Buizert, Christo ; Brook, Edward J. ; Breton, Daniel J. ; Fegyveresi, John ; Baggenstos, Daniel ; Orsi, Anais ; Severinghaus, Jeffrey ; Alley, Richard B. ; Albert, Mary ; Rhodes, Rachael H. ; McConnell, Joseph R. ; Sigl, Michael ; Maselli, Olivia ; Gregory, Stephanie ; Ahn, Jinho. / Observing and modeling the influence of layering on bubble trapping in polar firn. In: Journal of Geophysical Research. 2015 ; Vol. 120, No. 6. pp. 2558-2574.
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Mitchell, LE, Buizert, C, Brook, EJ, Breton, DJ, Fegyveresi, J, Baggenstos, D, Orsi, A, Severinghaus, J, Alley, RB, Albert, M, Rhodes, RH, McConnell, JR, Sigl, M, Maselli, O, Gregory, S & Ahn, J 2015, 'Observing and modeling the influence of layering on bubble trapping in polar firn', Journal of Geophysical Research, vol. 120, no. 6, pp. 2558-2574. https://doi.org/10.1002/2014JD022766

Observing and modeling the influence of layering on bubble trapping in polar firn. / Mitchell, Logan E.; Buizert, Christo; Brook, Edward J.; Breton, Daniel J.; Fegyveresi, John; Baggenstos, Daniel; Orsi, Anais; Severinghaus, Jeffrey; Alley, Richard B.; Albert, Mary; Rhodes, Rachael H.; McConnell, Joseph R.; Sigl, Michael; Maselli, Olivia; Gregory, Stephanie; Ahn, Jinho.

In: Journal of Geophysical Research, Vol. 120, No. 6, 01.01.2015, p. 2558-2574.

Research output: Contribution to journalArticle

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AU - Mitchell, Logan E.

AU - Buizert, Christo

AU - Brook, Edward J.

AU - Breton, Daniel J.

AU - Fegyveresi, John

AU - Baggenstos, Daniel

AU - Orsi, Anais

AU - Severinghaus, Jeffrey

AU - Alley, Richard B.

AU - Albert, Mary

AU - Rhodes, Rachael H.

AU - McConnell, Joseph R.

AU - Sigl, Michael

AU - Maselli, Olivia

AU - Gregory, Stephanie

AU - Ahn, Jinho

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N2 - Interpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn. Much work has been done to understand the processes affecting air transport in the open pores of the firn, but a paucity of data from air trapped in bubbles in the firn-ice transition region has limited the ability to constrain the effect of bubble closure processes. Here we present high-resolution measurements of firn density, methane concentrations, nitrogen isotopes, and total air content that show layering in the firn-ice transition region at the West Antarctic Ice Sheet (WAIS) Divide ice core site. Using the notion that bubble trapping is a stochastic process, we derive a new parameterization for closed porosity that incorporates the effects of layering in a steady state firn modeling approach. We include the process of bubble trapping into an open-porosity firn air transport model and obtain a good fit to the firn core data. We find that layering broadens the depth range over which bubbles are trapped, widens the modeled gas age distribution of air in closed bubbles, reduces the mean gas age of air in closed bubbles, and introduces stratigraphic irregularities in the gas age scale that have a peak-to-peak variability of ~10 years at WAIS Divide. For a more complete understanding of gas occlusion and its impact on ice core records, we suggest that this experiment be repeated at sites climatically different from WAIS Divide, for example, on the East Antarctic plateau.

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Mitchell LE, Buizert C, Brook EJ, Breton DJ, Fegyveresi J, Baggenstos D et al. Observing and modeling the influence of layering on bubble trapping in polar firn. Journal of Geophysical Research. 2015 Jan 1;120(6):2558-2574. https://doi.org/10.1002/2014JD022766