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Brook E. (2005). Tiny Bubbles Tell All. Science, 310, 1285–1287.
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Spahni R., Chappellaz J., Stocker T., Loulergue L., Hausammann G., Kawamura K., Fluckiger J., Schwander J., Raynaud D., Masson-Delmotte V. & Jouzel J. (2005). Atmospheric Methane and Nitrous Oxide of the Late Pleistocene from Antarctic Ice Cores. Science, 310, 1317–1321.
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Udisti, R.; Becagli, S.; Castellano, E.; Delmonte, B.; Jouzel, J.; Petit, J.R.; Schwander, J.; Stenni, B.; Wolff, E.W. (2004). Stratigraphic correlations between the European Project for Ice Coring in Antarctica (EPICA) Dome C and Vostok ice cores showing the relative variations of snow accumulation over the past 45 kyr. J. Geophys. Res., 109.
Abstract: High-resolution chemistry analysis and electrical measurements performed on two ice core records (European Project for Ice Coring in Antarctica (EPICA) Dome C and Vostok) spanning the last 45 kyr allow stratigraphic correlations by matching volcanic events. Several common events were identified along the two ice cores on the basis of acidity and sulphate spikes in snow layers. Timescales were matched through comparison with isotope (?D) profiles and using the Antarctic cold reversal (ACR) minimum, a 10Be peak, and a dust spike as temporal checkpoints. Ratios of relative snow accumulation at the two sites during the Holocene, in the glacial-interglacial transition and in the last part of the glacial period, were reconstructed by finding the best fit between Dome C and Vostok depths recording the same events. After accounting for thinning of the layers as they are buried within the glacier, the Dome C-Vostok accumulation ratio, expected to be roughly constant from the conventional accumulation-temperature-isotope approach, is 1.12 for the glacial period but increases to as much as 1.44 for a large part of the Holocene. Glaciological effects, mainly related to the geographic origin of the Vostok ice along the Ridge B-Vostok axis, can account for only a minor fraction of this change. Instead, we argue that accumulation variability between the cores stems from differential changes in atmospheric circulation during these respective climatic periods at the two sites. Regional changes in atmospheric circulation are proposed with a negative anomaly in Dome C, a positive accumulation anomaly in Vostok, or a combination of both during glacial climate. Our approach may help to improve ice core dating by: (1) revealing anomalies in accumulation-rate estimation based on the classical thermodynamic method and (2) supporting the necessity to take into account contributions due to changes in atmospheric circulation processes.
Keywords: 0325 Atmospheric Composition and Structure: Evolution of the atmosphere; 1620 Global Change: Climate dynamics; 1863 Hydrology: Snow and ice; 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 9310 Information Related to Geographic Region: Antarctica
Programme: 960
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Röthlisberger, R.; Mulvaney, R.; Wolff, E.W.; Hutterli, M.A.; Bigler, M.; Sommer, S.; Jouzel, J. (2002). Dust and sea salt variability in central East Antarctica (Dome C) over the last 45 kyrs and its implications for southern high-latitude climate. Geophysical research letters, 29.
Abstract: A detailed record of non-sea-salt calcium, a proxy for dust, and sea-salt sodium, a proxy for sea salt, covering the last 45 kyr is presented. It shows that in the first part of the transition from the last glacial period to the Holocene (18–15 kyr BP), the changes in dust flux mainly reflect changes at the dust source, namely vegetation cover and local climate. The changes in the later part of the transition (12–11 kyr BP) are similar in extent to the changes seen in sea salt and most likely reflect a reorganization of the atmospheric circulation. During the last glacial period, considerable variation of dust but not of sea salt is observed, pointing to climatic changes in Patagonia, the main dust source for Dome C. A comparison of the glacial records from Dome C and Taylor Dome suggests that similar influences controlled aerosol input at both sites during this period.
Keywords: 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 1620 Global Change: Climate dynamics; 9310 Information Related to Geographic Region: Antarctica; 0368 Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry
Programme: 960
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Flückiger, J.; Monnin, E.; Stauffer, B.; Schwander, J.; Stocker, T.F.; Chappellaz, J.; Raynaud, D.; Barnola, J.-M. (2002). High-resolution Holocene N2O ice core record and its relationship with CH4 and CO2. Global biogeochemical cycles, 16.
Abstract: Nitrous oxide (N2O) concentration records exist for the last 1000 years and for time periods of rapid climatic changes like the transition from the last glacial to today's interglacial and for one of the fast climate variations during the last ice age. Little is known, however, about possible N2O variations during the more stable climate of the present interglacial (Holocene) spanning the last 11 thousand years. Here we fill this gap with a high-resolution N2O record measured along the European Project for Ice Coring in Antarctica (EPICA) Dome C Antarctic ice core. On the same ice we obtained high-resolution methane and carbon dioxide records. This provides the unique opportunity to compare variations of the three most important greenhouse gases (after water vapor) without any uncertainty in their relative timing. The CO2 and CH4 records are in good agreement with previous measurements on other ice cores. The N2O concentration started to decrease in the early Holocene and reached minimum values around 8 ka (<260 ppbv) before a slow increase to its preindustrial concentration of ?265 ppbv.
Keywords: 0325 Atmospheric Composition and Structure: Evolution of the atmosphere; 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 1610 Global Change: Atmosphere; 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology
Programme: 960
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Barnes, P.R.F.; Wolff, E.W.; Mulvaney, R.; Udisti, R.; Castellano, E.; Röthlisberger, R.; Steffensen, J.-P. (2002). Effect of density on electrical conductivity of chemically laden polar ice. J. Geophys. Res., 107.
Abstract: Electrical conductivity measurements made using the dielectric profiling technique (DEP) are compared to chemical data from the top 350 m of the Dome C ice core in Antarctica. The chemical data are used to calculate the concentration of the major acidic impurities in the core: sulphuric acid and hydrochloric acid. The conductivity coefficients in solid ice for sulphuric acid (?H2SO4) and hydrochloric acid (?HCl) are found to be 4.9 and 4.5 S m?1M?1. These are consistent with previously found values for the acid conductivity coefficient at different sites and suggest that the same conductivity mechanisms are important in all polar ice. A method of rolling regression analysis is used to find the variation of the pure ice conductivity (?? pure) and the conductivity coefficient of sulphuric acid, ?H2SO4, with depth. Then ?? pure and ?H2SO4are assessed against changes in core density and hence volume fraction of ice, v, due to the inclusion of air bubbles in the firn. Looyenga's model for dielectric mixtures applied to conduction in firn broadly predicts the variation observed in ?? purebut does not fit well for ice above 110 m. A previous application of the theory of percolation in random lattices is used to model the conductivity coefficient in firn. The coefficient ?H2SO4 is linked to vby the power law: ?H2SO4(v) ? ?H2SO4(1) (v ? vc)t; where vc is a threshold volume fraction below which no conduction can take place and is related to the geometry of the conducting lattice being modeled. The value of the exponent tis also dependent on the structure of the lattice and is here found to be t = 2.5, which is slightly lower than the previously obtained value of t = 2.7 for a structure where each grain has between 14 and 16 nearest neighbors. This model is consistent with the concept of conduction, via liquid H2SO4, taking place at two grain boundaries for firn. The model does not, however, preclude conduction taking place via acid situated at three grain boundaries or in an interconnected vein network at densities above 640 kg m?3.
Keywords: 0634 Electromagnetics: Measurement and standards; 1863 Hydrology: Snow and ice; 1894 Hydrology: Instruments and techniques; 9310 Information Related to Geographic Region: Antarctica
Programme: 960
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Polenta G. and the BRAIN collaboration. (2006). The BRAIN CMB polarisation experiment.
Abstract: Francesco Melchiorri Conference, Rome 12 th April 2006
Programme: 915
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Masi S. F. M. and the BRAIN collaboration. (2006). The BRAIN CMB polarisation experiment.
Abstract: Workshop Concordia , Rome 26-28 th April 2006
Programme: 915
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Cressiot C. and the BRAIN collaboration. (2006). The BRAIN experiment.
Abstract: Conference SF2A Paris 26 th June 2006
Programme: 915
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Masi S. F. M. and the BRAIN collaboration. (2006). The first campaign of the BRAIN experiment in DOME-C.
Abstract: Conference SCAR XXIX, Hobart Tasmania 9-19 th July 2006
Programme: 915
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