Multiphase Reactive Transport and Platelet Ice Accretion in the Sea Ice of McMurdo Sound, Antarctica

2018 ◽  
Vol 123 (1) ◽  
pp. 324-345 ◽  
Author(s):  
J. J. Buffo ◽  
B. E. Schmidt ◽  
C. Huber
Keyword(s):  
Sea Ice ◽  
Reactive Transport ◽  
Ice Accretion ◽  
Mcmurdo Sound ◽  
Platelet Ice

scholarly journals Platelet ice and the land-fast sea ice of McMurdo Sound, Antarctica

2001 ◽  
Vol 33 ◽  
pp. 21-27 ◽  
Author(s):  
Inga J. Smith ◽  
Patricia J. Langhorne ◽  
Timothy G. Haskell ◽  
H. Joe Trodahl ◽  
Russell Frew ◽  
...  
Keyword(s):  
Sea Ice ◽  
Isotopic Analysis ◽  
Field Work ◽  
Weddell Sea ◽  
Water Interface ◽  
Ice Shelf ◽  
Columnar Growth ◽  
Mcmurdo Sound ◽  
Ice Water ◽  
Platelet Ice

AbstractDendritic crystals of platelet ice appear beneath the columnar land-fast sea ice of McMurdo Sound, Antarctica. These leaf-like crystals are frozen into place by the advancing columnar growth. The platelets most probably begin to appear during July although in some parts of the Sound they may not appear at all. In addition, the amount and extent of platelet ice within the Sound varies from year to year. Previous authors have suggested that the formation of platelet ice is linked to the presence of the nearby ice shelf. It is a matter of debate whether these platelets form at depth and then float upwards or whether they grow in slightly supercooled water at the ice/water interface. The phenomenon is similar to that observed in the Weddell Sea region, but previous authors have suggested the two regions may experience different processes. This paper presents the results of field-work conducted in McMurdo Sound in 1999. Ice-structure analysis, isotopic analysis and salinity and temperature measurements near the ice/water interface are presented. Freezing points are calculated, and the possible existence of supercooling is discussed in relation to existing conjectures about the origin of platelets.

scholarly journals Structure of sea ice in McMurdo Sound, Antarctica

2001 ◽  
Vol 33 ◽  
pp. 5-12 ◽  
Author(s):  
Stephen J. Jones ◽  
Brian T. Hill
Keyword(s):  
Sea Ice ◽  
Thin Layer ◽  
Horizontal Plane ◽  
Ice Cores ◽  
First Year ◽  
Mcmurdo Sound ◽  
Axis Orientation ◽  
Preferred Direction ◽  
The Mean ◽  
Platelet Ice

AbstractSea-ice cores from 11 sites in McMurdo Sound, Antarctica, were collected in 1982 and their crystallography examined. All but one were first-year sea ice. The cores, approximately 2 m long, consisted typically of a thin layer of granular or snow ice (approximately 0.1 m) followed by columnar-grained ice in the top metre and platelet ice in the bottom metre. Salinity and temperature measurements are reported. The columnar-grained ice usually had a strong preferred c-axis orientation in the horizontal plane and also showed a change in this preferred direction with depth in the ice. The mean c-axis orientation, however, usually aligned well with measured or implied currents in the Sound. The platelets were usually aligned with c axis horizontal or close to horizontal, and did not exhibit as marked a preferred orientation as the columnar-grained ice.

Evidence for platelet ice accretion in Arctic sea ice development

1995 ◽  
Vol 100 (C6) ◽  
pp. 10905 ◽  
Author(s):  
M. O. Jeffries ◽  
K. Schwartz ◽  
K. Morris ◽  
A. D. Veazey ◽  
H. R. Krouse ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Sea Ice ◽  
Ice Accretion ◽  
Arctic Sea ◽  
Platelet Ice

scholarly journals Dynamic, in situ measurement of sea-ice characteristic length

2001 ◽  
Vol 33 ◽  
pp. 339-344 ◽  
Author(s):  
Colin Fox ◽  
Tim G. Haskell ◽  
Hyuck Chung
Keyword(s):  
Sea Ice ◽  
Characteristic Length ◽  
Ice Sheet ◽  
In Situ Measurement ◽  
Effective Characteristic ◽  
Mcmurdo Sound ◽  
Periodic Loading ◽  
Flexural Response ◽  
Measurement Signal

AbstractWe present a method for measuring the characteristic length of sea ice based on fitting to a recently found solution for the flexural response of a floating ice sheet subject to localized periodic loading. Unlike previous techniques, the method enables localized measurements at single frequencies of geophysical interest, and since the measurements may be synchronously demodulated, gives excellent rejection of unwanted measurement signal (e.g. from ocean swell). The loading mechanism is described and we discuss how the effective characteristic length may be determined using a range of localized measurements. The method is used to determine the characteristic length of the sea ice in McMurdo Sound, Antarctica.

scholarly journals Using electron backscatter diffraction to measure full crystallographic orientation in Antarctic land-fast sea ice

2018 ◽  
Vol 64 (247) ◽  
pp. 771-780 ◽  
Author(s):  
PAT WONGPAN ◽  
DAVID J. PRIOR ◽  
PATRICIA J. LANGHORNE ◽  
KATHERINE LILLY ◽  
INGA J. SMITH
Keyword(s):  
Sea Ice ◽  
Crystallographic Orientation ◽  
Electron Backscatter Diffraction ◽  
Preferred Orientation ◽  
Angle Distribution ◽  
Crystal Preferred Orientation ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
First Time ◽  
Platelet Ice

ABSTRACTWe have mapped the full crystallographic orientation of sea ice using electron backscatter diffraction (EBSD). This is the first time EBSD has been used to study sea ice. Platelet ice is a feature of sea ice near ice shelves. Ice crystals accumulate as an unconsolidated sub-ice platelet layer beneath the columnar ice (CI), where they are subsumed by the advancing sea–ice interface to form incorporated platelet ice (PI). As is well known, in CI the crystal preferred orientation comprises dominantly horizontal c-axes, while PI has c-axes varying between horizontal and vertical. For the first time, this study shows the a-axes of CI and PI are not random. Misorientation analysis has been used to illuminate the possible drivers of these alignments. In CI the misorientation angle distribution from random pairs and neighbour pairs of grains are indistinguishable, indicating the distributions are a consequence of crystal preferred orientation. Geometric selection during growth will develop the a-axis alignment in CI if ice growth in water is fastest parallel to the a-axis, as has previously been hypothesised. In contrast, in PI random-pair and neighbour-pair misorientation distributions are significantly different, suggesting mechanical rotation of crystals at grain boundaries as the most likely explanation.

Impact of the B-15 iceberg “stranding event” on the physical and biological properties of sea ice in McMurdo Sound, Ross Sea, Antarctica

2008 ◽  
Vol 20 (6) ◽  
pp. 593-604 ◽  
Author(s):  
J.-P. Remy ◽  
S. Becquevort ◽  
T.G. Haskell ◽  
J.-L. Tison
Keyword(s):  
Sea Ice ◽  
Ross Sea ◽  
Ice Cores ◽  
Ice Cover ◽  
Biological Properties ◽  
Trophic Relationships ◽  
Oceanic Circulation ◽  
Mcmurdo Sound ◽  
Algae Biomass ◽  
Second Year

AbstractIce cores were sampled at four stations in McMurdo Sound (Ross Sea) between 1999 and 2003. At the beginning of year 2000, a very large iceberg (B-15) detached itself from the Ross Ice Shelf and stranded at the entrance of the Sound, preventing the usual oceanic circulation purging of the annual sea ice cover from this area. Ice textural studies showed that a second year sea ice cover was built-up at three out of the four stations: ice thickness increased to about 3 m. Repeated alternation of columnar and platelet ice appeared, and bulk salinity showed a strong decrease, principally in the upper part of the ice sheet, with associated brine volume decrease. Physical modification influenced the biology as well. By decreasing the light and space available for organisms in the sea ice cover, the stranding of B-15 has i) hampered autotrophic productivity, with chlorophyllaconcentration and algae biomass significantly lower for second year ice stations, and ii) affected trophic relationships such as the bacterial biomass/chlaconcentration correlation, or the autotrophic to heterotrophic ratio.

scholarly journals Turbulent heat transfer as a control of platelet ice growth in supercooled under-ice ocean boundary layers

Ocean Science ◽  
2016 ◽  
Vol 12 (2) ◽  
pp. 507-515 ◽  
Author(s):  
Miles G. McPhee ◽  
Craig L. Stevens ◽  
Inga J. Smith ◽  
Natalie J. Robinson
Keyword(s):  
Heat Transfer ◽  
Sea Ice ◽  
Turbulent Heat Transfer ◽  
Late Winter ◽  
Turbulent Heat ◽  
Ice Shelves ◽  
Ice Growth ◽  
Turbulent Heat Exchange ◽  
Fast Ice ◽  
Platelet Ice

Abstract. Late winter measurements of turbulent quantities in tidally modulated flow under land-fast sea ice near the Erebus Glacier Tongue, McMurdo Sound, Antarctica, identified processes that influence growth at the interface of an ice surface in contact with supercooled seawater. The data show that turbulent heat exchange at the ocean–ice boundary is characterized by the product of friction velocity and (negative) water temperature departure from freezing, analogous to similar results for moderate melting rates in seawater above freezing. Platelet ice growth appears to increase the hydraulic roughness (drag) of fast ice compared with undeformed fast ice without platelets. Platelet growth in supercooled water under thick ice appears to be rate-limited by turbulent heat transfer and that this is a significant factor to be considered in mass transfer at the underside of ice shelves and sea ice in the vicinity of ice shelves.

scholarly journals Structural characteristics of congelation and platelet ice and their role in the development of antarctic land-fast sea ice

1993 ◽  
Vol 39 (132) ◽  
pp. 223-238 ◽  
Author(s):  
M. O. Jeffries ◽  
W. F. Weeks ◽  
R. Shaw ◽  
K. Morris
Keyword(s):  
Growth Rates ◽  
Ice Cores ◽  
Current Control ◽  
Water Current ◽  
Minor Amount ◽  
Mcmurdo Sound ◽  
Ice Growth ◽  
Fast Ice ◽  
Ice Fabrics ◽  
Platelet Ice

AbstractIce cores were obtained in January 1990 from the land-fast ice in McMurdo Sound for a study of variations in texture, fabric, sub-structure, composition and development. Two primary ice types were observed, congelation and platelet, with a minor amount of frazil ice. Congelation ice growth precedes platelet-ice accretion. Congelation-ice fabrics show frequent moderate to strong alignments, a phenomenon believed to be due to water-current control of selective ice-crystal growth. Platelet ice originates at the base of the congelation ice, initially as a porous latticework of tabular ice crystals which subsequently consolidate by congelation of the interstitial water. Interstitial congelation-ice fabrics generally have little or no alignment, indicating the reduced effect of currents within the platelet latticework prior to solidification. Platelet-crystal textures range from small, wavy-edged forms to large, blade-like forms. Platelet-crystal fabrics indicate that, in addition to being randomly oriented, the platelet latticeworks commonly include many crystals with their flat (0001) faces oriented both parallel and normal to the base of the overlying ice. Plate-width data suggest that the interstitial congelation ice-growth rates remain similar to those of the overlying congelation ice. This effective increase in growth rates probably happens because the latticework of accumulating platelets ahead of the freezing interface ensures that the water within the platelet layer is at the freezing point and less heat has to be removed from platelet-rich water than from platelet-free water for a given thickness of congelation ice to grow. The negative oceanic heat flux associated with platelet-ice formation in McMurdo Sound explains why McMurdo Sound fast ice is thicker than Ross Sea pack ice, and also why it reaches a greater thickness than Arctic fast ice grown in a similar polar marine climate. Plate widths in the McMurdo Sound congelation ice suggest, however, that it grows no faster than Arctic congelation ice.

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