Ice formation in the subcooled brine environment

AbstractSixty-three ice cores were collected in the Bellingshausen and Amundsen Seas in August and September 1993 during a cruise of the R.V. Nathaniel B. Palmer. The structure and stable-isotopic composition (18O/16O) of the cores were investigated in order to understand the growth conditions and to identify the key growth processes, particularly the contribution of snow to sea-ice formation. The structure and isotopic composition of a set of 12 cores that was collected for the same purpose in the Bellingshausen Sea in March 1992 are reassessed. Frazil ice and congelation ice contribute 44% and 26%, respectively, to the composition of both the winter and summer ice-core sets, evidence that the relatively calm conditions that favour congelation-ice formation are neither as common nor as prolonged as the more turbulent conditions that favour frazil-ice growth and pancake-ice formation. Both frazil- and congelation-ice layers have an av erage thickness of 0.12 m in winter, evidence that congelation ice and pancake ice thicken primarily by dynamic processes. The thermodynamic development of the ice cover relies heavily on the formation of snow ice at the surface of floes after sea water has flooded the snow cover. Snow-ice layers have a mean thickness of 0.20 and 0.28 m in the winter and summer cores, respectively, and the contribution of snow ice to the winter (24%) and summer (16%) core sets exceeds most quantities that have been reported previously in other Antarctic pack-ice zones. The thickness and quantity of snow ice may be due to a combination of high snow-accumulation rates and snow loads, environmental conditions that favour a warm ice cover in which brine convection between the bottom and top of the ice introduces sea water to the snow/ice interface, and bottom melting losses being compensated by snow-ice formation. Layers of superimposed ice at the top of each of the summer cores make up 4.6% of the ice that was examined and they increase by a factor of 3 the quantity of snow entrained in the ice. The accumulation of superimposed ice is evidence that melting in the snow cover on Antarctic sea-ice floes ran reach an advanced stage and contribute a significant amount of snow to the total ice mass.

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Frazil Ice Formation,

10.21236/ada147425 ◽

1984 ◽

Cited By ~ 1

Author(s):

R. Ettema ◽

M. F. Karim ◽

J. F. Kennedy

Keyword(s):

Ice Formation ◽

Frazil Ice

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Experimental studies on the transformation from firn to ice in the wet-snow zone of temperate glaciers

Annals of Glaciology ◽

10.1017/s0260305500012143 ◽

1997 ◽

Vol 24 ◽

pp. 181-185 ◽

Cited By ~ 3

Author(s):

Katsuhisa Kawashima ◽

Tomomi Yamada

Keyword(s):

Experimental Studies ◽

Ice Formation ◽

Compression Tests ◽

Densification Rate ◽

Overburden Pressure ◽

Proportionality Constant ◽

Wet Snow ◽

Water Saturated ◽

The Relationship ◽

Good Agreement

The densification of water-saturated firn, which had formed just above the firn-ice transition in the wet-snow zone of temperate glaciers, was investigated by compression tests under pressures ranging from 0.036 to 0.173 MPa, with special reference to the relationship between densification rate, time and pressure. At each test, the logarithm of the densification rate was proportional to the logarithm of the time, and its proportionality constant increased exponentially with increasing pressure. The time necessary for ice formation in the firn aquifer was calculated using the empirical formula obtained from the tests. Consequently, the necessary time decreased exponentially as the pressure increased, which shows that the transformation from firn in ice can be completed within the period when the firn aquifer exists, if the overburden pressure acting on the water-saturated firn is above 0.12–0.14 MPa. This critical value of pressure was in good agreement with the overburden pressure obtained from depth–density curves of temperate glaciers. It was concluded that the depth of firn–ice transition was self-balanced by the overburden pressure to result in the concentration between 20 and 30 m.

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First record of the occurrence of sea ice in the Cordillera Darwin fjords (54°S), Chile

Annals of Glaciology ◽

10.1017/aog.2021.3 ◽

2021 ◽

pp. 1-11

Author(s):

Charles Salame ◽

Inti Gonzalez ◽

Rodrigo Gomez-Fell ◽

Ricardo Jaña ◽

Jorge Arigony-Neto

Keyword(s):

Time Series ◽

Sea Ice ◽

First Record ◽

Ice Formation ◽

Future Research ◽

Landsat 8 ◽

Surface Salinity ◽

Air Temperatures ◽

Aerial Reconnaissance ◽

High Precipitation

Abstract This paper provides the first evidence for sea-ice formation in the Cordillera Darwin (CD) fjords in southern Chile, which is farther north than sea ice has previously been reported for the Southern Hemisphere. Initially observed from a passenger plane in September 2015, the presence of sea ice was then confirmed by aerial reconnaissance and subsequently identified in satellite imagery. A time series of Sentinel-1 and Landsat-8 images during austral winter 2015 was used to examine the chronology of sea-ice formation in the Cuevas fjord. A longer time series of imagery across the CD was analyzed from 2000 to 2017 and revealed that sea ice had formed in each of the 13 fjords during at least one winter and was present in some fjords during a majority of the years. Sea ice is more common in the northern end of the CD, compared to the south where sea ice is not typically present. Is suggested that surface freshening from melting glaciers and high precipitation reduces surface salinity and promotes sea-ice formation within the semi-enclosed fjord system during prolonged periods of cold air temperatures. This is a unique set of initial observations that identify questions for future research in this remote area.

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Calorimetric analysis of ice onset temperature during cryoablation: a model approach to identify early predictors of effective applications

Scientific Reports ◽

10.1038/s41598-021-95204-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Elena Campagnoli ◽

Andrea Ballatore ◽

Valter Giaretto ◽

Matteo Anselmino

Keyword(s):

Cooling Rate ◽

Latent Heat ◽

Bovine Liver ◽

Onset Temperature ◽

Ice Formation ◽

Scanning Calorimetry ◽

Calorimetric Analysis ◽

Early Predictors ◽

Latent Heat Capacity ◽

Model Approach

AbstractAim of the present study is to analyze thermal events occurring during cryoablation. Different bovine liver samples underwent freezing cycles at different cooling rate (from 0.0075 to 25 K/min). Ice onset temperature and specific latent heat capacity of the ice formation process were measured according to differential scanning calorimetry signals. A computational model of the thermal events occurring during cryoablation was compiled using Neumann’s analytical solution. Latent heat (#1 = 139.8 ± 7.4 J/g, #2 = 147.8 ± 7.9 J/g, #3 = 159.0 ± 4.1 J/g) of all liver samples was independent of the ice onset temperature, but linearly dependent on the water content. Ice onset temperature was proportional to the logarithm of the cooling rate in the range 5 ÷ 25 K/min (#3a = − 12.2 °C, #3b = − 16.2 °C, #3c = − 6.6 °C at 5K/min; #3a = − 16.5 °C, #3b = − 19.3 °C, #3c = − 11.6 °C at 25 K/min). Ice onset temperature was associated with both the way in which the heat involved into the phase transition was delivered and with the thermal gradient inside the tissue. Ice onset temperature should be evaluated in the early phase of the ablation to tailor cryoenergy delivery. In order to obtain low ice trigger temperatures and consequent low ablation temperatures a high cooling rate is necessary.

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