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Goujon, C.; Barnola, J.-M.; Ritz, C. (2003). Modeling the densification of polar firn including heat diffusion: Application to close-off characteristics and gas isotopic fractionation for Antarctica and Greenland sites. J. Geophys. Res., 108.
Abstract: Modeling the densification of polar firn is essential to estimate variations of close-off characteristics (density, close-off depth, delta age) in relation with past climate parameters (temperature and accumulation rates). Furthermore, the air composition in the firn is modified by gravitational and thermal fractionation, and stable isotope measurements of permanent gases like nitrogen or argon can provide information on the amplitude of these fractionations. In this work, we propose a new model coupling firn densification and heat diffusion. In addition to the determination of the firn thickness and gas-ice age differences, the model allows a reconstruction of the time evolution of the temperature for different sites in Antarctica (Vostok) and Greenland (GISP2) and therefore the evolution of gravitational and thermal isotopic fractionations in firn. Under present-day conditions, the modeled profiles are in good agreement with the available temperature measurements in firn. For sites with low accumulation rates such as Vostok, the results show the existence of temperature gradients in the firn column even when no rapid climatic changes occur. The comparison of the modeled ?15N results to measurements allows to better constrain the ?18O-temperature relationship, used to infer the surface temperature history, and for GISP2, the model validates the long-term borehole-based temperature.
Keywords: 1827 Hydrology: Glaciology; 1863 Hydrology: Snow and ice; 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology
Programme: 902
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Jouzel J., Vimeux F., Caillon N., Delaygue G., Hoffmann G., Masson Delmotte V. & Parre. (2003). Magnitude of the isotope-temperature scaling for interpretation of central Antarctic ice cores. J. Geophys. Res., 108, 1029–1046.
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. (2003). Evolution of chemical peak shapes in the Dome C, Antarctica, ice core. J. Geophys. Res., 108.
Keywords: 1863 Hydrology: Snow and ice; 9310 Information Related to Geographic Region: Antarctica; 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 3999 Mineral Physics: General or miscellaneous; 0325 Atmospheric Composition and Structure: Evolution of the atmosphere
Programme: 960
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Schmidt, M., R. Graul, et al. (2003). The Schauinsland CO2 record: 30 years of continental observations and their implications for the variability of the European CO2 budget. J. Geophys. Res., 108(d19), 4619.
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Cosme, E.; Genthon, C.; Martinerie, P.; Boucher, O.; Pham, M. (2002). The sulfur cycle at high-southern latitudes in the LMD-ZT General Circulation Model. J. Geophys. Res., 107.
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Beine H.J., Honrath R.E., Domine F., Simpson W.R. & Fuentes J.D. (2002). NOx during background and ozone depletion periods at Alert: Fluxes above the snow surface. J. Geophys. Res., 107(d21), 4584.
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Lengagne T., Aubin T., Jouventin P. & Lauga J. (2000). Perceptual salience of individually distinctive features in the calls of adult king penguins. J. Acoust. Soc. Am., 107(1), 508–516.
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Leyrit H. (1995).107, 9–32.
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Delmas R. (1998). Ice-core records of global climate and environment changes. Journal of earth system science, 107(4), 307–319.
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Gabrielli P., Barbante C., Planchon F A.M., Ferrari C., Delmonte B. & Boutron C.F. (2003). Changes in the occurrence of heavy metals in polar ice during the last climatic cycles, with special emphasis on the possible link between cosmic dust accretion rate and the 100 kyr cycle. Journal de Physique, 107, 499–503.
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