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A semi-empirical model has been developed to reproduce glacial–interglacial changes of continental dust and marine sodium concentrations (factor of ∼50 and ∼5, respectively) observed in inland Antarctic ice cores. The model uses conceptual pathways of aerosols within the high troposphere; assumes the dry deposition of impurities on the Antarctic surface; uses estimates of aerosol transit times taken independent of climate; assumes a temperature-dependent removal process during aerosol pathways from the mid-latitudes. The model is fitted to the data over the last four climate cycles from Vostok and EPICA Dome C Antarctic sites. As temperature is cooling, the aerosol response suggests different modes of climate couplings between latitudes, which can be continuous or below temperature thresholds for sodium and dust, respectively. The model estimates a southern South America dust source activity two to three times higher for glacial periods than for the Holocene and a glacial temperature over the Southern Ocean 3–5 °C cooler. Both estimates appear consistent with independent observations. After removal of temperature effects, dust and sodium residuals for both sites show orbital frequencies in opposite phase at the precession timescale. Such long-term insolation-related modulation of terrestrial and marine aerosol input, could provide a chemical pacemaker useful for refining ice core chronologies. [ABSTRACT FROM AUTHOR]

A comparison is made of the bryophyte floras of two small maritime Antarctic islands lying at similar latitudes and with similar climates and glacial topographies, but differing markedly in their origins, geologies and derived soils. Signy Island (South Orkney Islands) is geologically complex with substrata ranging from strongly acidic schist to strongly alkaline marble and amphibolite, while Deception Island (South Shetland Islands) is volcanic with mildly alkaline lava, tuff, basalt and fine ash. Both islands are relatively low and approximately half ice-free. Signy has a long history of glacial fluctuations, allowing a wide range of cryptogamic community types to develop since the mid-Holocene (at least 5500 years ago), while most present substrata on Deception are very recent, following extensive habitat change resulting from eruptions in 1839–1842 and 1967–1970. The unstable nature of Deception's terrain greatly restricts habitat and plant community diversity. Nevertheless, both islands have the same number of bryophyte species and similar numbers that are exclusive to each island. Of the total of 81 moss and 19 liverwort species for both islands, only 36 and six species, respectively, are common to both islands. Much of this difference in species diversity is due to the greater substratum stability, abundance of surface water and the calcareous rocks and soils on Signy, and to geothermal activity at many sites on Deception. [ABSTRACT FROM AUTHOR]

abstract A deep ice core drilled at Dome Fuji, East Antarctica was analyzed for the CO2 concentration using a wet extraction method in order to reconstruct its atmospheric variations over the past 320 kyr, which includes three full glacial–interglacial climatic cycles, with a mean time resolution of about 1.1 kyr. The CO2 concentration values derived for the past 65 kyr are very close to those obtained from other Antarctic ice cores using dry extraction methods, although the wet extraction method is generally thought to be inappropriate for the determination of the CO2 concentration. The comparison between the CO2 and Ca2+ concentrations deduced from the Dome Fuji core suggests that calcium carbonate emitted from lands was mostly neutralized in the atmosphere before reaching the central part of Antarctica, or that only a small part of calcium carbonate was involved in CO2 production during the wet extraction process. The CO2 concentration for the past 320 kyr deduced from the Dome Fuji core varies between 190 and 300 ppmv, showing clear glacial–interglacial variations similar to the result of the Vostok ice core. However, for some periods, the concentration values of the Dome Fuji core are higher by up to 20 ppmv than those of the Vostok core. There is no clear indication that such differences are related to variations of chemical components of Ca2+ , microparticle and acidity of the Dome Fuji core. [ABSTRACT FROM AUTHOR]

The bed topography of Jutulstraumen is of interest in connection with glaciological modelling for climatic and geological studies. During the Norwegian Antarctic Research Expedition 1996/97 (NARE 96/97) 971 km of bed topography profiles were mapped using ground-penetrating radar (GPR) and a global positioning system (GPS). As additional information to the GPR data for the map compilation, surface features connected to the bed topography were identified in optical satellite images, and relative velocities derived from interferometric synthetic aperture radar (INSAR) data were interpreted using principles of ice flow related to the bed topography. Grids (250 x 250 m) covering the area 73° to 71°S, 0° to 4°E of bed topography and ice thickness were developed. Several observations are confirmed by the independent data sets. The Jutulstraumen outlet glacier shows extreme topography with subglacial plateaus and deep valleys due to faulting. A previously unmapped valley in connection with the fault system is identified. The data sets provide evidence of a grounding line position 6-20 km further inland than previously expected, and a trough occurs 60 km up-glacier from this position. [ABSTRACT FROM AUTHOR]

The Weddell Sea in the Antarctica is one of the two indentations of the continent and lies to the east of Palmer Land and west of Coat's Land. It is a major feature of the earth with length of about 700 miles and breadth about 1200 miles. While these strong winds of the glacial anticyclones are sufficiently powerful to force the pack away from the shore, they at the same time bring out snow measured by the millions of tons and at very low temperatures. This, added to the seawater, causes it to congeal quickly when the relatively warm blizzard has been succeeded by the cold calm.