Acoustic detection of ice crystals in Antarctic waters

Penrose, John D.; Conde, M.; Pauly, Tim

doi:10.1029/93jc03507

Cited by 33 publications

(33 citation statements)

References 14 publications

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“…They found that roughly two thirds (54 Gt a −1 ) of the net melt beneath the Filchner-Ronne Ice Shelf is generated at shallow depths (mean 375 m) near the Ronne Ice Shelf front. Relatively fresh, supercooled water plumes containing platelet crystals have been observed north of the ice front in western Prydz Bay [60] . The temperature values immediately below the Amery Ice Shelf measured by CTD are −2.25℃ at AM01 and −2.14℃ at AM02 [61] .…”

Section: Discussionmentioning

confidence: 99%

Mass budgets of the Lambert, Mellor and Fisher Glaciers and basal fluxes beneath their flowbands on Amery Ice Shelf

et al. 2007

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Section: Discussionmentioning

confidence: 99%

Mass budgets of the Lambert, Mellor and Fisher Glaciers and basal fluxes beneath their flowbands on Amery Ice Shelf

et al. 2007

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“…To the authors' knowledge, there has been only one documented instance of an ISW plume rising to the surface upon exiting the ice shelf cavity. This was inferred by a flux of platelet ice crystals retrieved by netting and seen in echo sound records in front of the Amery Ice Shelf [ Penrose et al ., ]. In that case, the flux of platelets was also coincident with a plume of supercooled water emerging from the ice shelf cavity.…”

Section: Introductionmentioning

confidence: 99%

Evolution of a supercooled Ice Shelf Water plume with an actively growing subice platelet matrix

et al. 2014

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We use new observations in Western McMurdo Sound, combined with longitudinal hydrographic transects of the sound, to identify a northward-flowing Ice Shelf Water (ISW) plume exiting the cavity of the McMurdo-Ross Ice Shelf. We estimate the plume's net northward transport at 0.4 6 0.1 Sv, carving out a corridor approximately 35 km wide aligned with the Victoria Land Coast. Basal topography of the McMurdo Ice Shelf is such that the plume is delivered to the surface without mixing with overlying warmer water, and is therefore able to remain below the surface freezing temperature at the point of observation beneath first-year ice. Thus, the upper ocean was supercooled, by up to 50 mK at the surface, due to pressure relief from recent rapid ascent of the steep basal slope. The 70 m thick supercooled layer supports the growth and maintenance of a thick, semirigid, and porous matrix of platelet ice, which is trapped by buoyancy at the ice-ocean interface. Continued growth of individual platelets in supercooled water creates significant brine rejection at the top of the water column which resulted in convection over the upper 200 m thick, homogeneous layer. By examining the diffusive nature of the intermediate water between layers of ISW and High Salinity Shelf Water, we conclude that the ISW plume must have originated beneath the Ross Ice Shelf and demonstrate that it is likely to expand eastward across McMurdo Sound with the progression of winter.

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“…In the first, loose ice platelet crystals are suspended by turbulence or rise in the water column and are presumed to originate from interaction with an ice shelf. Dieckmann et al [1986] and Penrose et al [1994] observed loose platelets at depths as great as 250 m. In McMurdo Sound an episodic flux of these crystals has been inferred from observations of scatterers in the water column, which from mid‐May 2003 appeared concurrently with surface supercooling [ Leonard et al , 2006].…”

Section: Introductionmentioning

confidence: 99%

Observation and modeling of platelet ice fabric in McMurdo Sound, Antarctica

et al. 2010

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[1] During the annual growth of landfast ice in McMurdo Sound, Antarctica, an episodic flux of platelet ice crystals from the ocean contributes to the build up of a porous subice platelet layer, which is steadily incorporated into the sea ice cover as it thickens over winter. In November 2007, we examined the spatial variability of these processes by collecting sea ice cores, with simultaneous oceanographic observations, along an east-west transect in the sound. Previously identified draped and bladed platelet ice types were observed. In addition, we identify resumed columnar growth which appears to be a result of geometric selection from the subice platelet layer after the arrival of new platelet crystals from the ocean has ceased. A numerical model of mechanical platelet ice processes is developed that predicts crystal texture and c axis distributions, producing virtual incorporated platelet ice with known growth history. This model demonstrates how a disordered subice platelet layer arises from an initially flat interface and suggests that such a layer is more likely to form later in the growth season. The model also suggests how the grain boundary density in incorporated platelet ice responds to changes in the flux of loose platelet crystals from the ocean. Application of this result to our 2007 platelet ice observations indicates that sea ice in western McMurdo Sound is subject to larger and more persistent platelet fluxes than the ice in the east. This is consistent with the pattern of in situ supercooling just beneath the ocean surface.

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Acoustic detection of ice crystals in Antarctic waters

Cited by 33 publications

References 14 publications

Mass budgets of the Lambert, Mellor and Fisher Glaciers and basal fluxes beneath their flowbands on Amery Ice Shelf

Mass budgets of the Lambert, Mellor and Fisher Glaciers and basal fluxes beneath their flowbands on Amery Ice Shelf

Evolution of a supercooled Ice Shelf Water plume with an actively growing subice platelet matrix

Observation and modeling of platelet ice fabric in McMurdo Sound, Antarctica

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