Publications
106 results found
Barnes PRF, Wolff EW, Mulvaney R, 2006, A 44 kyr paleoroughness record of the Antarctic surface, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, Vol: 111, ISSN: 2169-897X
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- Citations: 11
Barnes PRF, Wolff EW, Mallard DC, 2006, Etching channels and grain-boundary grooves on ice surfaces in the scanning electron microscope, JOURNAL OF GLACIOLOGY, Vol: 52, Pages: 645-648, ISSN: 0022-1430
Glasscock JA, Barnes PRF, Plumb IC, et al., 2006, Photoelectrochemical hydrogen production using nanostructured α-Fe<sub>2</sub>O<sub>3</sub> electrodes, Conference on Solar Hydrogen and Nanotechnology, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
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- Citations: 1
Barnes PRF, Blake D, Glasscock JA, et al., 2006, Charge transport in Fe<sub>2</sub>O<sub>3</sub> films deposited on nanowire arrays, Conference on Solar Hydrogen and Nanotechnology, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Wolff EW, Cook E, Barnes PRF, et al., 2005, Signal variability in replicate ice cores, JOURNAL OF GLACIOLOGY, Vol: 51, Pages: 462-468, ISSN: 0022-1430
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- Citations: 23
Augustin L, Barbante C, Barnes PRF, et al., 2004, Eight glacial cycles from an Antarctic ice core, NATURE, Vol: 429, Pages: 623-628, ISSN: 0028-0836
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- Citations: 1385
Barnes PRF, Wolff EW, 2004, Distribution of soluble impurities in cold glacial ice, JOURNAL OF GLACIOLOGY, Vol: 50, Pages: 311-324, ISSN: 0022-1430
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- Citations: 50
Stauffer B, Flückiger J, Wolff E, et al., 2004, The EPICA deep ice cores: first results and perspectives, Pages: 93-100
Two deep ice cores are being drilled in Antarctica in the frame of the European Project for Ice Coring in Antarctica (EPICA). The Dome C ice core will provide more information about mechanisms of global climatic changes over several climatic cycles. The DML core, drilled at Kohnen station, will provide a detailed record over the last climatic cycle, which can be compared with Greenland records. The drilling at Dome C reached 3200 m depth during field season 2002/03, and the age of the ice at the bottom of the hole could be 900 000 years according to preliminary estimates. The depth at Kohnen station is 1564.6 m at present, corresponding to an age of about 55 000 years. Analyses along the top parts of both ice cores have provided interesting first results. A few selected results from these parts, mostly published already, are summarized. Only a few measurements are available from the deeper parts of both cores. Dielectric profiling and electrical conductivity measurements, performed in the field, provide continuous and high-resolution records concerning the acidity and the salt concentration of the ice. Continuous flow analyses and Fast Ion Chromatography also provide high-resolution records of several chemical compounds. These records give some clues as to the age scale of the EPICA Dome C ice core, but they also leave us with many open questions.
Barnes PRF, Wolff EW, Mallard DC, et al., 2003, SEM studies of the morphology and chemistry of polar ice, MICROSCOPY RESEARCH AND TECHNIQUE, Vol: 62, Pages: 62-69, ISSN: 1059-910X
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- Citations: 47
Barnes PRF, Wolff EW, Mader HM, et al., 2003, Evolution of chemical peak shapes in the Dome C, Antarctica, ice core, Journal of Geophysical Research: Atmospheres, Vol: 108, ISSN: 0148-0227
Interpretation of the chemical layers measured in ice cores requires knowledge of processes occurring after their deposition on the ice sheet. We present evidence for the diffusion of soluble ions in the top 350 m of the Dome C ice core, Antarctica, that helps in explaining the unexpectedly broad volcanic peaks observed at depth. A windowed-differencing operation applied to chemical time series indicates a damping of the signals over the past 11,000 years, independent of minor climatic variation, for sulfate and chloride, but not sodium. This implies a diffusive process is transporting both sulfate and chloride ions while the sodium ions remain fixed. We estimate the effective diffusivity in the core to be 4.7 × 10-8 m2 yr-1 for sulfate and 2.0 × 10-7 m2 yr-1 for chloride. These values are not high enough to significantly disrupt chemical interpretation in this section of core, but could be significant for older ice. The temperature of this section of ice (-53°C) implies that the predominantly acidic sulfate (and possibly chloride ions) will exist in the liquid phase while the sodium may be solid. We propose and develop two new mechanisms that could explain the observed solute movement. One involves the diffusion of solute through a connected vein network driven by liquid concentration imbalances instigated by the process of grain growth. The other considers a system of discontinuous veins where grain growth increases connectivity between isolated vein clusters allowing the spread of solute. In both mechanisms, the effective diffusivity is governed indirectly by grain growth rate; this may be a significant factor controlling effective diffusion in other cores.
Barnes PRF, Wolff EW, Mader HM, et al., 2003, Evolution of chemical peak shapes in the Dome C, Antarctica, ice core -: art. no. 4126, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, Vol: 108, ISSN: 2169-897X
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- Citations: 42
Barnes PRF, 2003, Comment on "Grain boundary ridge on sintered bonds between ice crystals" [J. Appl. Phys. 90, 5782, 2001], JOURNAL OF APPLIED PHYSICS, Vol: 93, Pages: 783-785, ISSN: 0021-8979
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- Citations: 12
Barnes PRF, Wolff EW, Mulvaney R, et al., 2002, Effect of density on electrical conductivity of chemically laden polar ice -: art. no. 2029, JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 107, ISSN: 2169-9313
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- Citations: 12
Barnes PRF, Mulvaney R, Wolff EW, et al., 2002, A technique for the examination of polar ice using the scanning electron microscope, JOURNAL OF MICROSCOPY-OXFORD, Vol: 205, Pages: 118-124, ISSN: 0022-2720
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- Citations: 35
Barnes PRF, Wolff EW, Mulvaney R, et al., 2002, Effect of density on electrical conductivity of chemically laden polar ice, Journal of Geophysical Research: Solid Earth, Vol: 107, ISSN: 2169-9313
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 (βH2SO4) and hydrochloric acid (βHCl) 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 (σ ∞pure) and the conductivity coefficient of sulphuric acid, βH2SO4, with depth. Then σ ∞pure and βH2SO4 are assessed against changes in core density and hence volume fraction of ice, v, due to the inclusion of air bubbles in the firm. Looyenga's model for dielectric mixtures applied to conduction in firm broadly predicts the variation observed in σ ∞pure but 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 βH2SO4 is linked to v by the power law: βH2SO4(v) ∝ βH2SO4(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 firm. The model does not, however, preclud
Barnes PRF, Mulvaney R, Robinson K, et al., 2002, Observations of polar ice from the Holocene and the glacial period using the scanning electron microscope, International Symposium on Ice Cores and Climate, Publisher: INT GLACIOLOGICAL SOC, Pages: 559-566, ISSN: 0260-3055
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- Citations: 32
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