The Growth, Structure, and Properties of Sea Ice

Weeks, W. F.; Ackley, Stephen F.

doi:10.1007/978-1-4899-5352-0_2

Cited by 488 publications

(652 citation statements)

References 123 publications

(139 reference statements)

Supporting

Mentioning

629

Contrasting

Unclassified

Order By: Relevance

“…As can be seen, c-axes in Figure 6b show a remarkable bias towards horizontal orientations, which is typical for columnar ice (cL Weeks and Ackley 1982). The axes in Figure 7b, on the other hand, lack this bias in orientations, thus indicating that this section represents platelet ice and not columnar ice.…”

Section: Lange: Basic Properties O[ Antarctic Sea Icementioning

confidence: 81%

Basic Properties of Antarctic Sea Ice as Revealed by Textural Analysis of Ice Cores

Lange

1988

A. Glaciology.

View full text Add to dashboard Cite

Sea ice constitutes a major element in the atmospheric, oceanographic and biological regime of the polar regions. Assessment of its fundamental properties requires interdisciplinary investigations on local, regional and global scales. Sea-ice structure and textural parameters of individual ice cores play a key role in such investigations. A proper characterization of sea-ice micro-structure is essential for an adequate classification of ice cores, an understanding of the growth processes of the sampled floe, and the identification of possible relationships between ice texture, and the physical, chemical and biological properties of sea ice. Investigations on ice cores which were obtained during three recent Antarctic expeditions in coastal waters of the eastern and southern Weddell Sea are reported. The basis for a number of physical, chemical and biological investigations is an assessment of the textural characteristics of each sea-ice core. These are derived by inspection of continuous thick sections, supplemented by an analysis of selected vertical and horizontal thin sections. Major results of this study can be summarized as follows: (i) in addition to the common ice classes, another sea-ice type, platelet ice, is identified; it is apparently unique to the coastal waters of Antarctica, near the ice-shelf edge, and (ii) different physical, chemical and biological sea-ice properties vary systematically with and are probably related to / controlled by the ice texture of the cores. INTRODUCTIONConsolidated sea-ice cover significantly restricts or prevents the exchange of energy and matter between the atmosphere and the underlying ocean . A remarkable seasonal variation in the areal extent of Antarctic sea ice between -3 mill. km 2 and 20 mill. km 2 introduces strongly varying boundary conditions in the oceanographic and atmospheric regime. This variation also affects the biological regime of the Southern Ocean. Besides causing environmental changes for many species in the water column, sea ice itself forms an ecological niche. Specially adapted micro-organisms inhabit the (brine-filled) pore space of the sea ice and provide a food source for other marine life during winter (Horner 1985).In order to understand and quantify the relevant processes in these three regimes, a better knowledge of fundamental sea-ice properties is an essential prerequisite. The only means of studying sea ice, besides the acquisition of remote-sensing data, lies in an assessment of basic ice properties of sampled cores. Here, ice structure and textural characteristics play a dominant role. They not only provide the basis for an ice stratigraphy as a guideline for subsequent analyses and for classification of the sampled floe, but also yield information on the development of the ice cover. In addition, physical, chemical and biological properties are related to and might even be controlled by ice structure to varying degrees. It is therefore a major principle of our sea-ice program to precede other investigations by detailed stru...

show abstract

Section: Lange: Basic Properties O[ Antarctic Sea Icementioning

confidence: 81%

Basic Properties of Antarctic Sea Ice as Revealed by Textural Analysis of Ice Cores

Lange

1988

A. Glaciology.

View full text Add to dashboard Cite

show abstract

“…(iv) Superimposed ice forms if snow melt water, percolating downwards, refreezes deeper in the snow or at the snow-ice interface, where temperature is lower than freezing [e.g., Nicolaus et al, 2009]. The ice formation mechanism can be tracked from specific textural and oxygen isotopes (d 18 O) signatures: granular type for frazil, columnar type for congelation, granular with low d 18 O for snowice formation, and polygonal granular for superimposed ice formation [Weeks and Ackley, 1986;Eicken, 1998;Tison et al, 1998;Haas et al, 2001;Tison et al, 2008]. Depending on the energetic constraints at the interfaces, ice can melt at its surface, at its base, and from the lateral edges of the ice floes.…”

Section: Sea Ice Mass Balancementioning

confidence: 99%

“…The salt trapped within sea ice during formation is hardly incorporated into the ice crystalline lattice [Weeks and Ackley, 1986] and rather remains dissolved in brine [see Hunke et al, 2011, for a review]. The bulk salinity of sea ice (i.e., for the combined ice and brine pockets) is usually much less than seawater, although brine salinity can be much higher.…”

Section: Controls Of Fluid Transport On Biogeochemical Tracersmentioning

confidence: 99%

“…Salt is trapped within sea ice during basal accretion and surface flooding. During basal ice growth, the salinity field is continuous across the ice-ocean interface, hence there is no immediate segregation of salt from the ice to the ocean [Weeks and Ackley, 1986] at the advancing front [Notz and Worster, 2009]. All nutrients included in the freezing seawater should conservatively follow salt and be incorporated into forming ice.…”

Section: Dissolved Tracersmentioning

confidence: 99%

See 1 more Smart Citation

Role of sea ice in global biogeochemical cycles: emerging views and challenges

Vancoppenolle

Meiners

Michel

et al. 2013

Quaternary Science Reviews

217

215

View full text Add to dashboard Cite

International audienceObservations from the last decade suggest an important role of sea ice in the global biogeochemical cycles, promoted by (i) active biological and chemical processes within the sea ice; (ii) fluid and gas exchanges at the sea ice interface through an often permeable sea ice cover; and (iii) tight physical, biological and chemical interactions between the sea ice, the ocean and the atmosphere. Photosynthetic micro-organisms in sea ice thrive in liquid brine inclusions encased in a pure ice matrix, where they find suitable light and nutrient levels. They extend the production season, provide a winter and early spring food source, and contribute to organic carbon export to depth. Under-ice and ice edge phytoplankton blooms occur when ice retreats, favoured by increasing light, stratification, and by the release of material into the water column. In particular, the release of iron - highly concentrated in sea ice - could have large effects in the iron-limited Southern Ocean. The export of inorganic carbon transport by brine sinking below the mixed layer, calcium carbonate precipitation in sea ice, as well as active ice-atmosphere carbon dioxide (CO₂) fluxes, could play a central role in the marine carbon cycle. Sea ice processes could also significantly contribute to the sulphur cycle through the large production by ice algae of dimethylsulfoniopropionate (DMSP), the precursor of sulphate aerosols, which as cloud condensation nuclei have a potential cooling effect on the planet. Finally, the sea ice zone supports significant ocean-atmosphere methane (CH₄) fluxes, while saline ice surfaces activate springtime atmospheric bromine chemistry, setting ground for tropospheric ozone depletion events observed near both poles. All these mechanisms are generally known, but neither precisely understood nor quantified at large scales. As polar regions are rapidly changing, understanding the large-scale polar marine biogeochemical processes and their future evolution is of high priority. Earth system models should in this context prove essential, but they currently represent sea ice as biologically and chemically inert. Palaeoclimatic proxies are also relevant, in particular the sea ice proxies, inferring past sea ice conditions from glacial and marine sediment core records and providing analogues for future changes. Being highly constrained by marine biogeochemistry, sea ice proxies would not only contribute to but also benefit from a better understanding of polar marine biogeochemical cycles

show abstract

“…The predominance of columnar crystals suggests that the majority of ice in these leads was formed under conditions where the latent heat flow was one-dimensional through the thickness of the ice cover [Weeks and Ackley, 1986]. This type of growth occurs after an initial ice cover has formed.…”

Section: Ice Productionmentioning

confidence: 99%

Ice growth and solar heating in springtime leads

Perovich¹,

Richter‐Menge²

2000

J. Geophys. Res.

View full text Add to dashboard Cite

Abstract. The large thermal contrast between the cold atmosphere and the relatively warm ocean in springtime leads results in rapid ice growth and large fluxes of heat from the ocean to the atmosphere and of salt from the ice to the ocean. However, the magnitude of the ice growth and of the fluxes is moderated by solar radiation absorbed in the ice and upper ocean. During the Arctic lead experiment (LeadEx) we monitored ice conditions at four springtime leads during the first few days of growth. The experiment took place in March-April 1992 in the Beaufort Sea (73øN, 146øW). Two of the leads were <200 rn in width, one was approximately a kilometer wide, and the fourth was quite large, more than a few kilometers wide. Ice thickness typically increased rapidly, with 15-20 cm of growth in the first few days. The crystallographic analysis of a series of ice cores taken across and along the edge of one of the smaller leads indicated that granular ice was more abundant along the edges (30%) of the lead than in the central part of the lead (10%). Observations suggest that thermodynamics processes dominated ice growth in these leads. Additional thickening of the ice at the edge of the leads was common because of rafting of the young ice and the accumulation of blowing snow. Ice temperature profiles exhibited a diurnal cycle induced by solar radiation, with daily oscillations of roughly 5øC On the basis, in part, of these earlier studies our expectations prior to the field experiment were straightforward. We believed that springtime leads were areas with great amounts of frazil ice production and tremendous heat fluxes from the ocean to the atmosphere. However, the observations we made during LeadEx indicate that this simple picture is incomplete and that the actual behavior of springtime leads is more complex. In this paper we use field observations from four springtime leads, along with a radiative transfer model, to explore ice production in leads and the impact of solar radiation on springtime leads. Field ExperimentLeadEx was a large interdisciplinary program directed at assessing the impact of leads on the atmosphere and ocean and understanding the processes of heat transfer to the atmosphere and salt to the upper ocean associated with freezing leads. The research team included oceanographers, atmospheric scientists, microwave remote sensing researchers, and ice physicists. Be-6541

show abstract

The Growth, Structure, and Properties of Sea Ice

Cited by 488 publications

References 123 publications

Basic Properties of Antarctic Sea Ice as Revealed by Textural Analysis of Ice Cores

Basic Properties of Antarctic Sea Ice as Revealed by Textural Analysis of Ice Cores

Role of sea ice in global biogeochemical cycles: emerging views and challenges

Ice growth and solar heating in springtime leads

Contact Info

Product

Resources

About