Horizontal patchiness in sympagic organisms of the Antarctic fast ice

1997 ◽  
Vol 9 (4) ◽  
pp. 399-406 ◽  
Author(s):  
Kerrie M. Swadling ◽  
John A.E. Gibson ◽  
David A. Ritz ◽  
Peter D. Nichols
Keyword(s):  
Sampling Design ◽  
Chlorophyll Concentration ◽  
Ice Cores ◽  
Horizontal Distribution ◽  
Coastal Site ◽  
Oithona Similis ◽  
Harpacticoid Copepods ◽  
Stephos Longipes ◽  
Fast Ice ◽  
The Antarctic

Patchiness in the horizontal distribution of sympagic organisms was studied at an Antarctic coastal site during autumn. A hierarchical sampling design (nested ANOVA) was used to assess variation in the biota on scales from metres to kilometres. Metazoan abundance, chlorophyll concentration and salinity were measured in 54 sea ice cores. The metazoan fauna was dominated by nauplii of the copepod Paralabidocera antarctica (6 × 104 to 4 × 105 m−2). Other copepods present included Stephos longipes, Oncaea curvata, Oithona similis, Ctenocalanus citer, and unidentified harpacticoid copepods. Chlorophyll a concentrations were generally much higher than values recorded at other sites at the same time of the year, reaching a maximum of 78 mg m−2. Metazoan abundances did not correlate strongly with chlorophyll or salinity. Significant variability in abundance of P. antarctica and O. similis, and chlorophyll concentration occurred at the scale of kilometres, whereas salinity and other metazoan abundances were not significantly variable at any of the scales examined. Considerable variation was evident at scales of less than one metre.

Hunting Behavior of a Marine Mammal Beneath the Antarctic Fast Ice

Science ◽  
1999 ◽  
Vol 283 (5404) ◽  
pp. 993-996 ◽  
Author(s):  
R. W. Davis ◽  
L. A. Fuiman ◽  
T. M. Williams ◽  
S. O. Collier ◽  
W. P. Hagey ◽  
...  
Keyword(s):  
Marine Mammal ◽  
Hunting Behavior ◽  
Fast Ice ◽  
The Antarctic

scholarly journals Characteristics of The Seasonal Sea Ice of East Antarctica and Comparisons with Satellite Observations

1987 ◽  
Vol 9 ◽  
pp. 85-91 ◽  
Author(s):  
T.H. Jacka ◽  
I. Allison ◽  
R. Thwaites ◽  
J.C. Wilson
Keyword(s):  
Sea Ice ◽  
Remote Sensing Data ◽  
Ice Cores ◽  
Open Water ◽  
Early Spring ◽  
Visual Channel ◽  
Antarctic Waters ◽  
Study Characteristics ◽  
Satellite Sensors ◽  
The Antarctic

A cruise to Antarctic waters from late October to mid December 1985 provided the opportunity to study characteristics of the seasonal sea ice from a time close to that of maximum extent through early spring decay. The area covered by the observations extends from the northern ice limit to the Antarctic coast between long. 50 °E and 80 E. Shipboard observations included ice extent, type and thickness, and snow depth. Ice cores were drilled at several sites, providing data on salinity and structure.The observations verify the highly dynamic and divergent nature of the Antarctic seasonal sea-ice 2one. Floe size and thickness varied greatly at all locations, although generally increasing from north to south. A high percentage of the total ice mass exhibited a frazil crystal structure, indicative of the existence of open water in the vicinity.The ground based observations are compared with observations from satellite sensors. The remote sensing data include the visual channel imagery from NOAA 6, NOAA 9, and Meteor 11. Comparisons are made with the operational ice charts produced (mainly from satellite data) by the Joint Ice Center, and with the analyses available by facsimile from Molodezhnaya.

scholarly journals Atmospheric Lead in Antarctic Ice during the Last Climatic Cycle

1988 ◽  
Vol 10 ◽  
pp. 5-9 ◽  
Author(s):  
Claude F. Boutron ◽  
Clair C. Patterson ◽  
Claude Lorius ◽  
V.N. Petrov ◽  
N.I. Barkov
Keyword(s):  
Isotope Dilution Mass Spectrometry ◽  
Ice Cores ◽  
Ice Age ◽  
Crustal Rock ◽  
Last Interglacial ◽  
Toxic Heavy Metal ◽  
Mass Spectrometry Technique ◽  
Spectrometry Technique ◽  
Last Ice Age ◽  
The Antarctic

Concentrations of lead (Pb) have been measured by the ultra-clean isotope dilution mass spectrometry technique in various sections of the Antarctic Dome C and Vostok deep ice cores, whose ages range from 3.85 to 155 ka B.P., in order to assess the natural, pre-human, sources of this toxic heavy metal in the global troposphere. Pb concentrations were very low, as low as about 0.3 pg Pb/g during the Holocene and probably during the last interglacial and part of the last ice age. On the other hand, they were quite high, up to about 40 pg Pb/g, during the Last Glacial Maximum and at the end of the penultimate ice age. Wind-blown dust from crustal rock and soil appears to be the main natural source of Pb in the global troposphere. Pb contribution from volcanoes is significant during periods of low Pb only. Contribution from the oceans is insignificant.

scholarly journals A study of different‑scale relationship between changes of the surface air temperature and the СО2 concentration in the atmosphere

2016 ◽  
Vol 56 (4) ◽  
pp. 533-544 ◽  
Author(s):  
N. V. Vakulenko ◽  
V. M. Kotlyakov ◽  
F. Parrenin ◽  
D. M. Sonechkin
Keyword(s):  
Carbon Dioxide ◽  
Time Series ◽  
Carbon Dioxide Concentration ◽  
Ice Cores ◽  
Glacial Maximum ◽  
Temperature Variations ◽  
The Holocene ◽  
The Antarctic ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A concept of the anthropogenic origin of the current global climate warming assumes that growth of concentration of the atmospheric carbon dioxide and other greenhouse gases is of great concern in this process. However, all earlier performed analyses of the Antarctic ice cores, covering the time interval of several glacial cycles for about 1 000 000 years, have demonstrated that the carbon dioxide concentration changes had a certain lag relative to the air temperature changes by several hundred years during every beginning of the glacial terminations as well as at endings of interglacials. In contrast to these findings, a recently published careful analysis of Antarctic ice cores (Parrenin et al., 2013) had shown that both, the carbon dioxide concentration and global temperature, varied almost synchronously during the transition from the last glacial maximum to the Holocene. To resolve this dilemma, a special technique for analysis of the paleoclimatic time series, based on the wavelets, had been developed and applied to the same carbon dioxide concentration and temperature time series which were used in the above paper of Parrenin et al., 2013. Specifically, a stack of the Antarctic δ18O time series (designated as ATS) and the deuterium Dome C – EPICA ones (dD) were compared to one another in order to: firstly, to quantitatively estimate differences between time scales of these series; and, secondly, to clear up the lead–lag relationships between different scales variations within these time series. It was found that accuracy of the mutual ATS and dD time series dating lay within the range of 80–160 years. Perhaps, the mutual dating of the temperature and carbon dioxide concentration series was even worse due to the assumed displacement of air bubbles within the ice. It made us to limit our analysis by the time scales of approximately from 800 to 6000 years. But it should be taken into account that any air bubble movement changes the time scale of the carbon dioxide series as a whole. Therefore, if a difference between variations in any temperature and the carbon dioxide time series is found to be longer than 80–160 years, and if these variations are timescale‑dependent, it means that the bubble displacements are not essential, and so these advancing and delays are characteristic of the time series being compared. Our wavelet‑based comparative and different‑scale analysis confirms that the relationships between the carbon dioxide concentration and temperature variations were essentially timescale‑dependent during the transition from the last glacial maximum to the Holocene. The carbon dioxide concentration variations were ahead of the temperature ones during transition from the glacial maximum to the Boelling – Alleroud warming as well as from the Young Drias cooling to the Holocene optimum. However, the temperature variations were ahead during the transition from the Boelling – Alleroud warming to the Young Drias cooling and during the transition from the Holocene optimum to the present‑day climate.

scholarly journals Climate since AD 1510 on Dyer Plateau, Antarctic Peninsula: evidence for recent climate change

1994 ◽  
Vol 20 ◽  
pp. 420-426 ◽  
Author(s):  
L. G. Thompson ◽  
D. A. Peel ◽  
E. Mosley-thompson ◽  
R. Mulvaney ◽  
J. Dal ◽  
...  
Keyword(s):  
19Th Century ◽  
Antarctic Peninsula ◽  
Chemical Species ◽  
Ice Cores ◽  
Warming Trend ◽  
Snow Accumulation ◽  
Annual Variations ◽  
Recent Climate ◽  
The 19Th Century ◽  
The Antarctic

A 480 year record of the oxygen-isotope ratios, dust content, chemical species and net accumulation from ice cores drilled in 1989 90 on Dyer Plateau in the Antarctic Peninsula is presented. The continuous analyses of small (sub-annual) samples reveal well-preserved annual variations in both sulfate content and δ18O, thus allowing an excellent time-scale to be established.This history reveals a recent pronounced warming in which the last two decades have been among the warmest in the last five centuries. Furthermore, unlike in East Antarctica, on Dyer Plateau conditions appear to have been fairly normal from AD 1500 to 1850 with cooler conditions from 1850 to 1930 and a warming trend dominating since 1930. Reconstructed annual layer thicknesses suggest an increase in net accumulation beginning early in the 19th century and continuing to the present. This intuitive conflict between increasing net accumulation and depleted δ18O (cooler climate) in the 19th century appears widespread in the peninsula region and challenges our understanding of the physical relationships among moisture sources, air temperatures and snow accumulation. The complex meteorological regime in the Antarctic Peninsula region complicates meaningful interpretation of proxy indicators and results in a strong imprint of local high-frequency processes upon the larger-scale climate picture.

scholarly journals Trace Elements in Antarctic Air and Snowfall

1985 ◽  
Vol 7 ◽  
pp. 12-19 ◽  
Author(s):  
A.L. Dick ◽  
D.A. Peel
Keyword(s):  
Trace Elements ◽  
Time Series Data ◽  
Ice Cores ◽  
Enrichment Factors ◽  
Atmospheric Composition ◽  
Series Data ◽  
Contamination Control ◽  
Polar Ice Sheets ◽  
Firm Basis ◽  
The Antarctic

Measurements of trace elements in snow and ice are frequently used to describe past atmospheric composition although there is no firm basis for assuming a direct connection. Trace-element concentrations have been measured on samples of aerosol and freshly fallen snow collected simultaneously from two sites in the Antarctic Peninsula during summer. Following improvements in contamination control, the reported concentrations and crustal enrichment factors of Cd, Cu, Pb and Zn in the aerosol are lower than any values previously reported from Antarctica. Even tighter controls will be required in the future.For a crustal element (A1) and for the marine cations (Na, Ca and K) a consistent ratio (0.48±0.31) for the concentration in air (pg m−3)/concentration in snow (pg g−1) is obtained for simultaneously collected samples. This supports a simple model of aerosol scavenging proposed by Junge which considers aerosol removal over polar ice sheets to be dominated by in-cloud processes. Averaged data for Cd, Cu, Pb and Zn from samples collected at different times appear to behave similarly. These findings suggest that there is no preferential scavenging by snowfall of either crustal or heavy metal components in contemporary aerosol. If proved more general in Antarctica this may help to simplify the interpretation of time series data from ice cores.

scholarly journals Spatial heterogeneity in the structure of fast ice level in the area of the research station “Ice base Cape of Baranov”

2018 ◽  
Vol 64 (4) ◽  
pp. 351-364
Author(s):  
V. A. Borodkin ◽  
S. M. Kovalev ◽  
A. I. Shushlebin
Keyword(s):  
Distinctive Feature ◽  
Thick Layer ◽  
Ice Cores ◽  
Open Water ◽  
Ice Thickness ◽  
Research Station ◽  
Group I ◽  
Stable Conditions ◽  
Fast Ice ◽  
Group Ii

Two ice coring transects in the Shokalsky Strait were made in order to analyze a spatialheterogeneity in the structure of fast ice in the area of the research station “Ice base Cape of Baranov”. The first transect was 16 km long made off the shore of Bolshevik Island in a western direction across the Shokalsky Strait. The second transect was made along the eastern shore of the Shokalsky Strait. Structural analysis of the recovered sea ice cores shows that fast ice in the Shokalsky Strait features a complicated multilayer structure formed of congelation ice, congelation-frazil ice, frazil slush, and infiltration formations. Various conditions of ice formation form the ices of various genetic types. In terms of ice thickness, a sequence of layer occurrence and type, all level fast ice of the Shokalsky Strait in the area of the station can be divided into three main groups. The group I, being the most common one, is the ice group formed directly in the strait, approximately outside the 100 m isobath. Its structure comprises three to four layers. The average ice thickness measured in the end of May was 132 cm. A distinctive feature of the ice belonging to (or associated with) this group is the presence of a distinct lamination in the texture pattern for almost all recovered ice cores. The ice of this group also has an increased salinity compared to the ice of other groups, especially in the upper layers.The ice of the group II prevails, mainly in closed bays or gulfs. This group ice forms in dynamically stable conditions. Formation of fast ice in these regions of the study area began some earlier than in other locations, and the thickness of this ice reached 160 cm or more.The ice of the group III is transitional from the group II to the group I. Its distinctive feature is the presence of a thick layer of rafting ice. The main place of its formation is the boundary of separation of fast ice with drifting ice or open water.In the Shokalsky Strait, in the bays and in the coastal regions, there was observed the spatial ordering of the columnar ice crystals. This feature was especially pronounced in level fast ice from the open part of the strait.

scholarly journals The Relationship of Ultrasonic Velocities to c-axis Fabrics and Relaxation Characteristics of Ice Cores from Byrd Station, Antarctica

1979 ◽  
Vol 24 (90) ◽  
pp. 147-153 ◽  
Author(s):  
A. J. Gow ◽  
H. Kohnen
Keyword(s):  
Ice Sheet ◽  
Ice Cores ◽  
Vertical Axis ◽  
P Wave ◽  
Ultrasonic Technique ◽  
Antarctic Ice Sheet ◽  
Axis Orientation ◽  
Crystal Anisotropy ◽  
The Antarctic ◽  
Relaxation Characteristics

Abstract Deep cores from Byrd Station were used to calibrate an ultrasonic technique of evaluating crystal anisotropy in the Antarctic ice sheet. Velocities measured parallel (V p ↓) and perpendicular (V p →) to the vertical axis of the cores yielded data in excellent agreement with the observed c-axis fabric profile and with the in-situ P-wave velocity profile measured parallel to the bore-hole axis by Bentley. Velocity differences ΔV (ΔV = V p ↓ – V p→) in excess of 140 m s−1 for cores from below 1300 m attest to the tight clustering of c-axes of crystals about the vertical, especially in the zone 1 300-1800 m. A small but significant decline in V p ↓ with ageing of the core, as deduced from Bentley’s down-hole data, is attributed to the formation of oriented cracks that occur in the ice cores as they relax from environmental stresses. This investigation of cores from the 2164 m thick ice sheet at Byrd Station establishes the ultrasonic technique as a viable method of monitoring relaxation characteristics of drilled cores and for determining the gross trends of c-axis orientation in ice sheets. The Byrd Station data, in conjunction with Barkov’s investigation of deep cores from Vostok, East Antarctica, also indicate that crystal anisotropy in the Antarctic ice sheet is dominated by a clustering of c-axes about a vertical symmetry axis.

scholarly journals Small-Scale variability of physical properties and structural characteristics of Antarctic fast ice

1994 ◽  
Vol 20 ◽  
pp. 61-66 ◽  
Author(s):  
A.L. Veazey ◽  
M.O. Jeffries ◽  
K. Morris
Keyword(s):  
Physical Properties ◽  
Structural Characteristics ◽  
Austral Summer ◽  
Ice Cores ◽  
Thin Layers ◽  
Small Scale ◽  
Axis Orientation ◽  
Layer Spacing ◽  
Frazil Ice ◽  
Fast Ice

The small-scale variability of physical properties and structural characteristics of multiple pairs of fast-ice cores obtained during the austral summer of 1991-92 at two Antarctic sites, McMurdo Sound (MCM) and Pine Island Bay (PIB), are examined and discussed with respect to the growth and decay of the sea ice. The ice at the MCM site was thicker than that at the PIB site and was covered by a somewhat thinner snowpack. While mean salinity and temperature of the ice at the two sites were similar, small-scale variations in both salinity and temperature were greater at PIB than at MCM. The ice sheet at MCM was a two-layer medium consisting of congelation ice overlying platelet ice. The ice from the PIB site, however, was composed of mainly frazil ice and layers of congelation ice with occasional thin layers of snow-ice at the surface of the cores. Crystal sub-structure measurements, c-axis orientation and brine-layer spacing from the MCM cores revealed that the congelation ice had moderately aligned, horizontally oriented c axes, suggesting that east-west currents off the southwest tip of Hut Point Peninsula control crystal-growth orientation.d others: Variability of physical and structural characteristics of Antarctic fast ice

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