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

Jacka, T. H.; Allison, Ian; Thwaites, Richard; Wilson, Jeff

doi:10.1017/s0260305500000446

Cited by 33 publications

(18 citation statements)

References 9 publications

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“…In the western Ross Sea, Jeffries and Weeks (1992) observed a frazil ice fraction varying from 2.3% to 88.5% with a mean of 38.5% 6 27%. Similarly, high frazil ice concentrations were found in the Indian Ocean sector (Allison and Qian 1985;Jacka et al 1987;Tison and Haren 1989).…”

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confidence: 93%

Study of the Impact of Ice Formation in Leads upon the Sea Ice Pack Mass Balance Using a New Frazil and Grease Ice Parameterization

Wilchinsky

Heorton

Feltham

et al. 2015

Journal of Physical Oceanography

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Leads are cracks in sea ice that often form because of deformation. During winter months, leads expose the ocean to the cold atmosphere, resulting in supercooling and the formation of frazil ice crystals within the mixed layer. Here the authors investigate the role of frazil ice formation in leads on the mass balance of the sea ice pack through the incorporation of a new module into the Los Alamos sea ice model (CICE). The frazil ice module considers an initial cooling of leads followed by a steady-state formation of uniformly distributed single size frazil ice crystals that precipitate to the ocean surface as grease ice. The grease ice is pushed against one of the lead edges by wind and water drag that the authors represent through a variable collection thickness for new sea ice. Simulations of the sea ice cover in the Arctic and Antarctic are performed and compared to a model that treats leads the same as the open ocean. The processes of ice formation in the new module slow down the refreezing of leads, resulting in a longer period of frazil ice production. The fraction of frazil-derived sea ice increases from 10% to 50%, corresponding better to observations. The new module has higher ice formation rates in areas of high ice concentration and thus has a greater impact within multiyear ice than it does in the marginal seas. The thickness of sea ice in the central Arctic increases by over 0.5 m, whereas within the Antarctic it remains unchanged.

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confidence: 93%

Study of the Impact of Ice Formation in Leads upon the Sea Ice Pack Mass Balance Using a New Frazil and Grease Ice Parameterization

Wilchinsky

Heorton

Feltham

et al. 2015

Journal of Physical Oceanography

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“…Structurally, pack ice is composed predominantly of frazil ice crystals, while fast ice consists of frazil ice and columnar/congelation ice [ Gow et al , 1998]. Sea ice charts derived from satellite imagery delineate between fast and pack ice and provide information on ice cover [e.g., Jacka et al , 1987]. Although these charts do not provide information on sea ice thickness, this is broadly related to ice coverage and generally increases from the ice edge to the coast [ Allison et al , 1993; Jacka et al , 1987].…”

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confidence: 99%

Profiles of dimethylsulphoniopropionate (DMSP), algal pigments, nutrients, and salinity in the fast ice of Prydz Bay, Antarctica

et al. 2003

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[1] Total dimethylsulphoniopropionate (DMSPt), chlorophyll a (Chl a), and algal marker pigments were measured in 12 fast ice cores collected from Prydz Bay, eastern Antarctica (68°-69°S, 77°-79°E) in October 1997 and November 1998. Patterns of DMSPt distribution through the ice were similar on spatial scales of meters to tens of kilometers within ice sheets grouped according to growth history. This reflects the association of DMSP in fast ice with autotrophic biomass distribution, which is intrinsically linked with ice growth and differed between the ice sheets. The 12 fast ice cores were divided into three groups on the basis of ice thickness and year. Concentrations of DMSPt ranged widely from 9 to 1478 nM with marked peaks occurring within each core. Mean DMSPt concentrations were higher (200 nM) in the medium first-year ice (0.7-1.2 m) than in the thick (>1.2 m) first-year ice (90 nM), mainly because of a local surface algal assemblage that may be atypical. The fast ice algal assemblages in surface, interior, and bottom ice were dominated by diatoms (Fucoxanthin:Chl a concentrations >80%). Dinoflagellates and haptophytes were generally small and variable components of the assemblages (Peridinin:Chl a 2-11% and 19 0 -hexanoyloxyfucoxanthin:Chl a 2-4%, respectively). Our data support the important contribution of diatoms to DMSP production in sea ice. Nutrient (nitrate, silicate, phosphate) concentrations were measured for one group of cores. Silicate and Chl a concentrations were significantly correlated (r = 0.30, P < 0.02, Pearson), implying that silicate availability may have regulated algal growth. The Si:P:N ratio in interior ice (27:1:10) was different to that in surface and bottom ice (46:1:23). We have summarized DMSP data reported from six Antarctic sea ice studies to investigate whether comparisons within the growing database need to consider differences in sea ice type, thickness, location, or season. Although concentrations from individual samples ranged over 4 orders of magnitude (<1 to >1000 nM, n = 410), the mean DMSP concentrations during spring/summer were within the range of 107-322 nM, with an overall mean of 178 nM. Mean DMSP concentrations in Antarctic sea ice appear to be comparable between studies and across the Antarctic sea ice zone. We estimate that the Antarctic sea ice zone may contain up to 9 Mmole sulphur as DMSP.

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“…Influenced by mesoscale cyclogenesis and strong offshore katabatic winds, much of this drift is of a generally divergent nature. As a result, in winter and spring Antarctic sea ice is a diverse combination of ice of different thicknesses and open water in leads and polynyas (Jacka et al, 1987;Wadhams et al, 1987;Allison et al, 1993). For example, in mid-to late spring for the Indian Ocean sector of the Southern Ocean, Allison and Worby (1994) found as much as 30% of the total pack was new ice less than 0.3 m thick while a further 30% was open water.…”

Section: Introductionmentioning

confidence: 99%

Sea‐ice conditions in the Ross Sea during spring 1996 as observed on SAR and AVHRR imagery

Hauser¹,

Lythe²,

Wendler³

2002

Atmosphere-Ocean

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The structure and properties of the sea-ice field in the western Ross Sea during the spring of 1996 are evaluated using data from the ERS-2 Synthetic Aperture Radar (SAR) and the Advanced Very High Resolution Radiometer (AVHRR) sensors. A multispectral classification method enabled separation of six ice types including fast ice, new ice, smooth first-year ice, rough first-year ice, thin new ice/wind roughened open water and glacial ice. In Terra Nova Bay it was observed that the size of the recurring polynya depended strongly on the strength of the consistent offshore winds arising from the strong katabatic wind flow down the Priestley and Reeves Glaciers. It appears that the presence and size of this feature is more dependent on atmospheric than on oceanographic forcing. The Terra Nova Bay Polynya is frequently not ice free, but covered, at least in part, by thin, new sea ice. During katabatic events, rows of new ice, formed in response to Langmuir circulations, are observed oriented perpendicular to the coastline. These structures are swept downstream where, under less turbulent conditions, they consolidate to form pancake ice and thicker ice floes. Elsewhere over the continental shelf sea-ice conditions changed little in over a month, indicating that much of the ice in this area is landfast.RÉSUMÉ [Traduit par la rédaction] On a évalué la structure et les propriétés du champ de glace de mer dans la partie ouest de la mer de Ross au printemps 1996 à partir de données des capteurs du radar à antenne synthétique (SAR) ERS-2 et du radiomètre perfectionné à très haut pouvoir de résolution (AVHRR). Une méthode de classification multispectrale a permis de subdiviser la glace en six types, dont la banquise côtière, la glace nouvelle, la glace de première année à surface lisse, la glace de première année à surface rugueuse, la glace nouvelle mince/eau libre à surface balayée par le vent et glace de glacier. Dans la baie de Terra Nova, on a observé que la taille de la polynie récurrente est largement fonction de la force des vents de terre générés par le vent catabatique en provenance des glaciers Priestley et Reeves. La présence et la taille de cet élément dépend plus du forçage atmosphérique que du forçage océanographique. Souvent, la polynie de la baie de Terra Nova n'est pas libre de glace, mais est plutôt couverte au moins en partie par une mince couche de glace de mer nouvelle. Au cours d'événements catabatiques, on observe des rangées de glace nouvelle qui sont formées en réponse à la circulation de Langmuir et orientées perpendiculairement au trait de côte. Ces structures sont entraînées vers l'aval où, dans des conditions moins turbulentes, elles fusionnent pour former des glaces en crêpes et des floes plus épais. Ailleurs sur la plate-forme continentale, les conditions de glace de mer ont peu changé dans l'espace de plus d'un mois, indiquant que dans cette région, la glace est en grande partie de la banquise côtière.

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

Cited by 33 publications

References 9 publications

Study of the Impact of Ice Formation in Leads upon the Sea Ice Pack Mass Balance Using a New Frazil and Grease Ice Parameterization

Study of the Impact of Ice Formation in Leads upon the Sea Ice Pack Mass Balance Using a New Frazil and Grease Ice Parameterization

Profiles of dimethylsulphoniopropionate (DMSP), algal pigments, nutrients, and salinity in the fast ice of Prydz Bay, Antarctica

Sea‐ice conditions in the Ross Sea during spring 1996 as observed on SAR and AVHRR imagery

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