Air bubbles and air-hydrate crystals in the Vostok ice core

Source: OAI


International Symposium on Physics of Ice Core Records. Shikotsukohan, Hokkaido, Japan, September 14-17, 1998. The geometrical properties of air-bubble and air-hydrate ensembles in the 3310-m deep Vostok core and in other ice cores were studied. The principle results are the following: 1) the size and abundance of air bubbles in polar ice depend on the temperature and accumulation rate prevailing over the time of the snow-ice transformation, 2) the climate signal imposed on the bubble properties at pore close-off is only slightly modified in the course of the bubble-hydrate transition (500–1250 m at present time at Vostok) and in the first, transient, phase of air-hydrate crystal growth (1150–1500 m); as a consequence, the last four glacial-interglacial cycles are resolved in variations of the number and size of air inclusions along the Vostok ice core, and 3) the air-bubble and air-hydrate records from polar ice cores can provide an independent experimental constraint on the temperature-accumulation relations in the past.

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Available from: V. Y. Lipenkov, Jul 06, 2015
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    • "In these ice sections we also measured the size of 100 clathrate hydrates and counted the number of microinclusions within the hydrates. For the hydrate volume estimation, either a spherical or a cylindrical visual approximation of the inclusion (depending on its shape) was used (Lipenkov, 2000). Detailed information on the Dome Fuji ice core has been published by the Dome-F Deep Coring Group (1998). "
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    ABSTRACT: To investigate factors influencing nucleation of air clathrate hydrates in polar ice sheets, we have performed high-resolution mapping of the distributions of soluble impurities, air bubbles and air-hydrate crystals versus depth in the Dome Fuji Antarctic ice. Significant correlation observed between the concentrations of air inclusions and impurities in ice along with frequent occurrence of impurities inside hydrate crystals suggest that micro-inclusions promote hydrate nucleation in the ice matrix. Our observations also show that the diffusive macroscopic-scale redistribution of air constituents in ice in the bubble-hydrate transition zone is controlled by the original sedimentary layering of soluble impurities acting as nucleation helpers. The results of this study are important for the correct interpretation of high-resolution gas analyses of ice cores and for better understanding the global bubble-to-hydrate transformation process in polar ice sheets.
    Full-text · Article · Nov 2010 · Journal of Glaciology
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    • "The way each individual component is processed is exactly the same for every bubble, which increases repeatability and comparability of the results gained with this method. In this contribution, profiles of bubble size and bubble number from the EDC and EDML cores are compared with data from the Vostok (Antarctica) core presented by Lipenkov (2000). In both the EDC and EDML cores, we can identify a particular class of bubbles, that Lipenkov termed 'microbubbles'. "
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    ABSTRACT: Air bubbles in ice cores play an essential role in climate research, not only because they contain samples of the palaeoatmosphere, but also because their shape, size and distribution provide information about the past firn structure and the embedding of climate records into deep ice cores. In this context, we present profiles of average bubble size and bubble number for the entire EDML (Antarctica) core and the top 600 m of the EDC (Antarctica) core, and distributions of bubble sizes from selected depths. The data are generated with an image-processing framework which automatically extracts position, orientation, size and shape of an elliptical approximation of each bubble from thick-section micrographs, without user interaction. The presented software framework allows for registration of overlapping photomicrographs to yield accurate locations of bubble-like features. A comparison is made between the bubble parameterizations in the EDML and EDC cores and data published on the Vostok (Antarctica) ice core. The porosity at the firn/ice transition is inferred to lie between 8.62% and 10.48% for the EDC core and between 10.56% and 12.61% for the EDML core.
    Full-text · Article · May 2010 · Journal of Glaciology
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    • "Not all glacier ice is bubbly: under several hundred meters of ice thickness, the pressure becomes so great that each air bubble dissolves in the ice to form a clathrate crystal, and the ice becomes relatively clear [Price, 1995]. However, when this ice becomes depressurized as its cover sublimates away (as in the Antarctic blue-ice areas where the albedos were measured), the bubbles reform [Lipenkov, 2000], so that the albedo of 0.55– 0.66 is observed at the surface. [3] In contrast to glacier ice, which forms by compression of snow, sea ice forms by freezing of liquid water. "

    Full-text · Article · Sep 2006 · Journal of Geophysical Research Atmospheres
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