scholarly journals Dynamic, in situ measurement of sea-ice characteristic length

2001 ◽  
Vol 33 ◽  
pp. 339-344 ◽  
Author(s):  
Colin Fox ◽  
Tim G. Haskell ◽  
Hyuck Chung
Keyword(s):  
Sea Ice ◽  
Characteristic Length ◽  
Ice Sheet ◽  
In Situ Measurement ◽  
Effective Characteristic ◽  
Mcmurdo Sound ◽  
Periodic Loading ◽  
Flexural Response ◽  
Measurement Signal

AbstractWe present a method for measuring the characteristic length of sea ice based on fitting to a recently found solution for the flexural response of a floating ice sheet subject to localized periodic loading. Unlike previous techniques, the method enables localized measurements at single frequencies of geophysical interest, and since the measurements may be synchronously demodulated, gives excellent rejection of unwanted measurement signal (e.g. from ocean swell). The loading mechanism is described and we discuss how the effective characteristic length may be determined using a range of localized measurements. The method is used to determine the characteristic length of the sea ice in McMurdo Sound, Antarctica.

Evolution of supercooling under coastal Antarctic sea ice during winter

2011 ◽  
Vol 23 (4) ◽  
pp. 399-409 ◽  
Author(s):  
Gregory H. Leonard ◽  
Patricia J. Langhorne ◽  
Michael J.M. Williams ◽  
Ross Vennell ◽  
Craig R. Purdie ◽  
...  
Keyword(s):  
Sea Ice ◽  
Freezing Point ◽  
Circulation Pattern ◽  
Late Winter ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
The North ◽  
Antarctic Sea Ice ◽  
Ice Production

AbstractHere we describe the evolution through winter of a layer of in situ supercooled water beneath the sea ice at a site close to the McMurdo Ice Shelf. From early winter (May), the temperature of the upper water column was below its surface freezing point, implying contact with an ice shelf at depth. By late winter the supercooled layer was c. 40 m deep with a maximum supercooling of c. 25 mK located 1–2 m below the sea ice-water interface. Transitory in situ supercooling events were also observed, one lasting c. 17 hours and reaching a depth of 70 m. In spite of these very low temperatures the isotopic composition of the water was relatively heavy, suggesting little glacial melt. Further, the water's temperature-salinity signature indicates contributions to water mass properties from High Salinity Shelf Water produced in areas of high sea ice production to the north of McMurdo Sound. Our measurements imply the existence of a heat sink beneath the supercooled layer that extracts heat from the ocean to thicken and cool this layer and contributes to the thickness of the sea ice cover. This sink is linked to the circulation pattern of the McMurdo Sound.

scholarly journals High-Resolution in Situ Measurement of Nitrate in Runoff from the Greenland Ice Sheet

2017 ◽  
Vol 51 (21) ◽  
pp. 12518-12527 ◽  
Author(s):  
Alexander D. Beaton ◽  
Jemma L. Wadham ◽  
Jon Hawkings ◽  
Elizabeth A. Bagshaw ◽  
Guillaume Lamarche-Gagnon ◽  
...  
Keyword(s):  
High Resolution ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
In Situ Measurement

scholarly journals Snow-driven uncertainty in CryoSat-2-derived Antarctic sea ice thickness – insights from McMurdo Sound

2019 ◽  
Vol 13 (4) ◽  
pp. 1409-1422
Author(s):  
Daniel Price ◽  
Iman Soltanzadeh ◽  
Wolfgang Rack ◽  
Ethan Dale
Keyword(s):  
Sea Ice ◽  
Snow Depth ◽  
Snow Accumulation ◽  
In Situ Measurements ◽  
Ice Thickness ◽  
Growth Season ◽  
Mcmurdo Sound ◽  
Sea Ice Thickness ◽  
Antarctic Sea Ice

Abstract. Knowledge of the snow depth distribution on Antarctic sea ice is poor but is critical to obtaining sea ice thickness from satellite altimetry measurements of the freeboard. We examine the usefulness of various snow products to provide snow depth information over Antarctic fast ice in McMurdo Sound with a focus on a novel approach using a high-resolution numerical snow accumulation model (SnowModel). We compare this model to results from ECMWF ERA-Interim precipitation, EOS Aqua AMSR-E passive microwave snow depths and in situ measurements at the end of the sea ice growth season in 2011. The fast ice was segmented into three areas by fastening date and the onset of snow accumulation was calibrated to these dates. SnowModel captures the spatial snow distribution gradient in McMurdo Sound and falls within 2 cm snow water equivalent (s.w.e) of in situ measurements across the entire study area. However, it exhibits deviations of 5 cm s.w.e. from these measurements in the east where the effect of local topographic features has caused an overestimate of snow depth in the model. AMSR-E provides s.w.e. values half that of SnowModel for the majority of the sea ice growth season. The coarser-resolution ERA-Interim produces a very high mean s.w.e. value 20 cm higher than the in situ measurements. These various snow datasets and in situ information are used to infer sea ice thickness in combination with CryoSat-2 (CS-2) freeboard data. CS-2 is capable of capturing the seasonal trend of sea ice freeboard growth but thickness results are highly dependent on what interface the retracked CS-2 height is assumed to represent. Because of this ambiguity we vary the proportion of ice and snow that represents the freeboard – a mathematical alteration of the radar penetration into the snow cover – and assess this uncertainty in McMurdo Sound. The ranges in sea ice thickness uncertainty within these bounds, as means of the entire growth season, are 1.08, 4.94 and 1.03 m for SnowModel, ERA-Interim and AMSR-E respectively. Using an interpolated in situ snow dataset we find the best agreement between CS-2-derived and in situ thickness when this interface is assumed to be 0.07 m below the snow surface.

An Improved Chamber for in situ Measurement of Primary Productivity by Sea Ice Algae

1982 ◽  
Vol 39 (3) ◽  
pp. 522-524 ◽  
Author(s):  
G. C. Schrader ◽  
R. Horner ◽  
G. F. Smith
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Primary Productivity ◽  
In Situ Measurement ◽  
Carbon Uptake ◽  
Ice Algae ◽  
Sea Ice Algae ◽  
Scuba Divers ◽  
Ice Conditions

A modified chamber was designed for in situ measurement of carbon uptake of micro-algae growing on the underside of sea ice. The chamber, operated by SCUBA divers, accommodates a wider range of ice conditions, has better holding capability, and reduces sample loss during retrieval.Key words: Arctic Ocean, sea ice algae, primary productivity

In situ measurement of the solar radiance distribution within sea ice in Liaodong Bay, China

2012 ◽  
Vol 71 ◽  
pp. 23-33 ◽  
Author(s):  
Zhantang Xu ◽  
Yuezhong Yang ◽  
Zhaohua Sun ◽  
Zhijun Li ◽  
Wenxi Cao ◽  
...  
Keyword(s):  
Sea Ice ◽  
In Situ Measurement ◽  
Liaodong Bay ◽  
Radiance Distribution

scholarly journals The tensile strength of first-year sea ice

1993 ◽  
Vol 39 (133) ◽  
pp. 609-618 ◽  
Author(s):  
J. A. Richter Menge ◽  
K. F. Jones
Keyword(s):  
Tensile Strength ◽  
Sea Ice ◽  
Maximum Stress ◽  
Ice Sheet ◽  
Tensile Load ◽  
Growth Direction ◽  
First Year ◽  
Strain Rates ◽  
Temperature Dependent

AbstractWe present the results of tests done to determine the tensile behavior of first-year columnar sea ice over a range of temperatures from −20° to −3°C and strain rates of 10−5and 10−3s−1. The temperature of a test specimen was dictated by its in-situ location within the sea-ice sheet; samples located near the top of the sea-ice sheet were tested at the lower temperatures. A tensile load was applied along the cylindrical axes of the test specimens, which were perpendicular to the growth direction of the ice. Results showed that the maximum stress reached during a test was most strongly influenced by temperature, while the failure strain and the modulus were principally affected by the loading rate. A model relating the tensile strength of the ice to its porosity based on temperature-dependent variations in the brine-pocket geometry is evaluated.

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