Relationship between ice decay and solar heating through open water in the Antarctic sea ice zone

Abstract In three ship-based field experiments, spectral albedos were measured at ultraviolet, visible, and near-infrared wavelengths for open water, grease ice, nilas, young “grey” ice, young grey-white ice, and first-year ice, both with and without snow cover. From the spectral measurements, broadband albedos are computed for clear and cloudy sky, for the total solar spectrum as well as for visible and near-infrared bands used in climate models, and for Advanced Very High Resolution Radiometer (AVHRR) solar channels. The all-wave albedos vary from 0.07 for open water to 0.87 for thick snow-covered ice under cloud. The frequency distribution of ice types and snow coverage in all seasons is available from the project on Antarctic Sea Ice Processes and Climate (ASPeCt). The ASPeCt dataset contains routine hourly visual observations of sea ice from research and supply ships of several nations using a standard protocol. Ten thousand of these observations, separated by a minimum of 6 nautical miles along voyage tracks, are used together with the measured albedos for each ice type to assign an albedo to each visual observation, resulting in “ice-only” albedos as a function of latitude for each of five longitudinal sectors around Antarctica, for each of the four seasons. These ice albedos are combined with 13 yr of ice concentration estimates from satellite passive microwave measurements to obtain the geographical and seasonal variation of average surface albedo. Most of the Antarctic sea ice is snow covered, even in summer, so the main determinant of area-averaged albedo is the fraction of open water within the pack.

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A late spring surge in the open water of the Antarctic sea ice pack

Geophysical Research Letters ◽

10.1029/1999gl900292 ◽

1999 ◽

Vol 26 (10) ◽

pp. 1481-1484 ◽

Cited By ~ 18

Author(s):

Andrew B. Watkins ◽

Ian Simmonds

Keyword(s):

Sea Ice ◽

Open Water ◽

Late Spring ◽

Antarctic Sea Ice ◽

The Antarctic ◽

Ice Pack

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Physical Processes determining the Antarctic Sea Ice Environment

Australian Journal of Physics ◽

10.1071/p96113 ◽

1997 ◽

Vol 50 (4) ◽

pp. 759 ◽

Cited By ~ 12

Author(s):

Ian Allison

Keyword(s):

Sea Ice ◽

Thickness Distribution ◽

Arctic Basin ◽

Open Water ◽

Ice Cover ◽

Dynamic Processes ◽

Surface Absorption ◽

Antarctic Sea Ice ◽

Ocean Atmosphere ◽

The Antarctic

The Antarctic sea ice zone undergoes one of the greatest seasonal surface changes on Earth, with an annual change in extent of around 15 × 10 6 km 2 . This ice, and its associated snow cover, plays a number of important roles in the ocean-atmosphere climate system: the high albedo ice cover restricts surface absorption of solar radiation and acts as a barrier to the exchange of mass and energy between the ocean and atmosphere, and salt rejected by the growing ice cover affects the ocean structure and circulation. Additionally, a number of sea ice feedback processes have the potential to play an important role in climate change. The extent to which a sea ice cover modifies ocean-atmosphere interaction is primarily determined by the thickness and concentration of the ice, but these themselves are determined by ocean and atmospheric interaction. The thickness distribution of the pack is determined by both thermodynamic and dynamic processes: most important at the geophysical scale are the dynamic processes of ice drift and deformation, and of lead formation. Compared to the ice cover in the central Arctic Basin, the Antarctic sea ice is highly mobile. Drifting buoy studies show that the Antarctic pack can move at speeds of up to 60 km per day or greater, and that around most of the Antarctic coast, the drift of the pack ice is generally divergent, with divergence rates of 10% or more per day being observed under some circumstances. Consequently there is generally some open water within the Antarctic pack and much of the total ice mass forms by rapid growth within these areas. This influences the crystal structure of the ice and results in a considerable portion of the Antarctic pack (up to 25% in spring-time) having a thickness of less than 0 · 3 m. In general much of the Antarctic sea ice only grows thermodynamically to about 0·5 m thick, with thickness increases beyond that resulting from the deformational processes of rafting and ridge-building.

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Salinity effects on cultured Neogloboquadrina pachyderma (sinistral) from high latitudes: new paleoenvironmental insights

Geo-Marine Letters ◽

10.1007/s00367-020-00677-1 ◽

2021 ◽

Vol 41 (1) ◽

Author(s):

Jacqueline Bertlich ◽

Nikolaus Gussone ◽

Jasper Berndt ◽

Heinrich F. Arlinghaus ◽

Gerhard S. Dieckmann

Keyword(s):

Sea Ice ◽

Cold Water ◽

Weddell Sea ◽

Wall Thickening ◽

High Latitudes ◽

Neogloboquadrina Pachyderma ◽

Antarctic Sea Ice ◽

The Antarctic ◽

Water Species ◽

Cold Water Species

AbstractThis study presents culture experiments of the cold water species Neogloboquadrina pachyderma (sinistral) and provides new insights into the incorporation of elements in foraminiferal calcite of common and newly established proxies for paleoenvironmental applications (shell Mg/Ca, Sr/Ca and Na/Ca). Specimens were collected from sea ice during the austral winter in the Antarctic Weddell Sea and subsequently cultured at different salinities and a constant temperature. Incorporation of the fluorescent dye calcein showed new chamber formation in the culture at salinities of 30, 31, and 69. Cultured foraminifers at salinities of 46 to 83 only revealed chamber wall thickening, indicated by the fluorescence of the whole shell. Signs of reproduction and the associated gametogenic calcite were not observed in any of the culture experiments. Trace element analyses were performed using an electron microprobe, which revealed increased shell Mg/Ca, Sr/Ca, and Na/Ca values at higher salinities, with Mg/Ca showing the lowest sensitivity to salinity changes. This study enhances the knowledge about unusually high element concentrations in foraminifera shells from high latitudes. Neogloboquadrina pachyderma appears to be able to calcify in the Antarctic sea ice within brine channels, which have low temperatures and exceptionally high salinities due to ongoing sea ice formation.

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Dark metabolism: a molecular insight into how the Antarctic sea‐ice diatom Fragilariopsis cylindrus survives long‐term darkness

New Phytologist ◽

10.1111/nph.15843 ◽

2019 ◽

Vol 223 (2) ◽

pp. 675-691 ◽

Cited By ~ 10

Author(s):

Fraser Kennedy ◽

Andrew Martin ◽

John P. Bowman ◽

Richard Wilson ◽

Andrew McMinn

Keyword(s):

Sea Ice ◽

Antarctic Sea Ice ◽

Fragilariopsis Cylindrus ◽

Dark Metabolism ◽

The Antarctic ◽

Insight Into

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Thermodynamics of slush and snow–ice formation in the Antarctic sea-ice zone

Deep Sea Research Part II Topical Studies in Oceanography ◽

10.1016/j.dsr2.2016.03.008 ◽

2016 ◽

Vol 131 ◽

pp. 75-83 ◽

Cited By ~ 7

Author(s):

Mathilde Jutras ◽

Martin Vancoppenolle ◽

Antonio Lourenço ◽

Frédéric Vivier ◽

Gauthier Carnat ◽

...

Keyword(s):

Sea Ice ◽

Ice Formation ◽

Antarctic Sea Ice ◽

The Antarctic

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

Annals of Glaciology ◽

10.3189/s0260305500000446 ◽

1987 ◽

Vol 9 ◽

pp. 85-91 ◽

Cited By ~ 6

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.

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Albedo of Young and First-Year Antarctic Sea Ice

Annals of Glaciology ◽

10.1017/s0260305500008909 ◽

1990 ◽

Vol 14 ◽

pp. 331 ◽

Cited By ~ 2

Author(s):

Richard Brandt ◽

Ian Allison ◽

Stephen Warren

Keyword(s):

Sea Ice ◽

Radiation Flux ◽

Open Water ◽

First Year ◽

Spectral Measurements ◽

Antarctic Sea Ice ◽

Antarctic Expedition ◽

Downward Radiation ◽

Radiation Measurements ◽

Snow Thickness

Reflection of solar radiation was studied in the seasonal sea-ice zone off East Antarctica on a cruise of the Australian Antarctic Expedition, October-December 1988. Spectral and total albedos were measured for grease ice, nilas, young grey ice, grey-white ice, snow-covered ice, and open water. Spectral measurements covered the region 400–1000 nm wavelength. For ice too thin to support our weight, the radiometers were mounted at the end of a 1.5 m rod extended out the door of a helicopter or from a basket hung from the ship's crane, using a positioning and leveling rack. Corrections had to be applied to the downward radiation flux because the helicopter or the crane was in the field of view of the cosine-collector. The fractional coverage of each of the ice types (and open water) was estimated hourly for the region near the ship, as well as the thickness of each ice type, and the snow thickness. Observations were carried out continuously during the four weeks the ship was in the ice, supplemented by occasional helicopter surveys covering larger areas. These observations, together with the radiation measurements, make possible the computation of area-average albedo for the East Antarctic sea-ice zone in spring.

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Albedo of the ice covered Weddell and Bellingshausen Seas

The Cryosphere ◽

10.5194/tc-6-479-2012 ◽

2012 ◽

Vol 6 (2) ◽

pp. 479-491 ◽

Cited By ~ 9

Author(s):

A. I. Weiss ◽

J. C. King ◽

T. A. Lachlan-Cope ◽

R. S. Ladkin

Keyword(s):

Sea Ice ◽

Surface Albedo ◽

Austral Summer ◽

Open Water ◽

Weddell Sea ◽

First Year ◽

Pack Ice ◽

Bellingshausen Sea ◽

The Mean ◽

The Antarctic

Abstract. This study investigates the surface albedo of the sea ice areas adjacent to the Antarctic Peninsula during the austral summer. Aircraft measurements of the surface albedo, which were conducted in the sea ice areas of the Weddell and Bellingshausen Seas show significant differences between these two regions. The averaged surface albedo varied between 0.13 and 0.81. The ice cover of the Bellingshausen Sea consisted mainly of first year ice and the sea surface showed an averaged sea ice albedo of αi = 0.64 ± 0.2 (± standard deviation). The mean sea ice albedo of the pack ice area in the western Weddell Sea was αi = 0.75 ± 0.05. In the southern Weddell Sea, where new, young sea ice prevailed, a mean albedo value of αi = 0.38 ± 0.08 was observed. Relatively warm open water and thin, newly formed ice had the lowest albedo values, whereas relatively cold and snow covered pack ice had the highest albedo values. All sea ice areas consisted of a mixture of a large range of different sea ice types. An investigation of commonly used parameterizations of albedo as a function of surface temperature in the Weddell and Bellingshausen Sea ice areas showed that the albedo parameterizations do not work well for areas with new, young ice.

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Last Glacial Maximum Antarctic sea ice linked with global mean ocean temperature: evidence from PMIP3, PMIP4 and MIROC-4m simulations

10.5194/egusphere-egu21-3550 ◽

2021 ◽

Author(s):

Tristan Vadsaria ◽

Sam Sherriff-Tadano ◽

Ayako Abe-Ouchi ◽

Takashi Obase ◽

Wing-Le Chan ◽

...

Keyword(s):

Southern Ocean ◽

Sea Ice ◽

Last Glacial Maximum ◽

Ocean Circulation ◽

Glacial Maximum ◽

Ocean Temperature ◽

Sea Ice Extent ◽

Last Glacial ◽

Antarctic Sea Ice ◽

The Antarctic

<p>Southern Ocean sea ice and oceanic fronts are known to play an important role on the climate system, carbon cycles, bottom ocean circulation, and Antarctic ice sheet. However, many models of the previous Past-climate Model Intercomparison Project (PMIP) underestimated sea-ice extent (SIE) for the Last Glacial Maximum (LGM)(Roche et al., 2012; Marzocchi and Jensen, 2017), mainly because of surface bias (Flato et al., 2013) that may have an impact on mean ocean temperature (MOT). Indeed, recent studies further suggest an important link between Southern Ocean sea ice and mean ocean temperature (Ferrari et al., 2014; Bereiter et al., 2018 among others). Misrepresent the Antarctic sea-ice extent could highly impact deep ocean circulation, the heat transport and thus the MOT. In this study, we will stress the relationship between the distribution of Antarctic sea-ice extent and the MOT through the analysis of the PMIP3 and PMIP4 exercise and by using a set of MIROC models. To date, the latest version of MIROC improve its representation of the LGM Antarctic sea-ice extent, affecting the deep circulation and the MOT distribution (Sherriff-Tadano et al., under review).</p><p>Our results show that available PMIP4 models have an overall improvement in term of LGM sea-ice extent compared to PMIP3, associated to colder deep and bottom ocean temperature. Focusing on MIROC (4m) models, we show that models accounting for Southern Ocean sea-surface temperature (SST) bias correction reproduce an Antarctic sea-ice extent, 2D-distribution, and seasonal amplitude in good agreement with proxy-based data. Finally, using PMIP-MIROC analyze, we show that it exists a relationship between the maximum SIE and the MOT, modulated by the Antarctic intermediate and bottom waters.</p>

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