A Field and Laboratory Study of Wave Damping by Grease Ice
Abstract In a field and laboratory study we discuss the formation, growth, and wave-absorption properties of grease ice. Our field observations show that grease-ice formation occurs under cold windy conditions in both leads and polynyas. In leads grease ice forms in the open water, then is herded to...
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Language: | English |
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Cambridge University Press (CUP)
1981
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Online Access: | http://dx.doi.org/10.1017/s0022143000015392 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000015392 |
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crcambridgeupr:10.1017/s0022143000015392 2024-06-23T07:54:15+00:00 A Field and Laboratory Study of Wave Damping by Grease Ice Martin, Seelye Kauffman, Peter 1981 http://dx.doi.org/10.1017/s0022143000015392 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000015392 en eng Cambridge University Press (CUP) Journal of Glaciology volume 27, issue 96, page 283-313 ISSN 0022-1430 1727-5652 journal-article 1981 crcambridgeupr https://doi.org/10.1017/s0022143000015392 2024-06-05T04:03:16Z Abstract In a field and laboratory study we discuss the formation, growth, and wave-absorption properties of grease ice. Our field observations show that grease-ice formation occurs under cold windy conditions in both leads and polynyas. In leads grease ice forms in the open water, then is herded to the down-wind edge of the lead; in polynyas a Langmuir circulation herds the grease ice into long plumes parallel to the wind. In the laboratory we grow grease ice in a wave tank and measure its wave absorption properties for single-frequency, two-dimensional waves. On a large scale we find that the thickness of the grease ice, which increases away from the paddle, is determined by a balance between the wave-momentum flux and the free-surface tilt. On a small scale our photographs show that the crystals which make up the grease ice consist of discs measuring about 1 mm in diameter and 1–10 µm thick, which at low rates of shear sinter together into larger clumps yielding a viscosity increase. To measure this non-linear viscosity, we study the decay of wave amplitude between two critical distances measured inwards from the leading edge. The first occurs when the depth of grease ice exceeds k −1 where k is the wave number; the second further distance is a line of transition from liquid to solid behavior which we call the dead zone. Between these two distances the wave amplitude decays with a linear slope α , which increases as ( a 0 k ) 2 where a 0 is the wave amplitude in open water. Concurrent measurements of ice concentration show that it increases from values of 18–22% at the leading edge to a local maximum of 32–44% at the dead zone, while the values at the dead zone increase non-linearly with a 0 k . Finally, comparison of the observed α to that calculated from a yield-stress viscosity model shows if the yield-stress coefficient is proportional to the incident wave-momentum flux, the model predicts the observed α . Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Langmuir ENVELOPE(-67.150,-67.150,-66.967,-66.967) Journal of Glaciology 27 96 283 313 |
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Open Polar |
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Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
description |
Abstract In a field and laboratory study we discuss the formation, growth, and wave-absorption properties of grease ice. Our field observations show that grease-ice formation occurs under cold windy conditions in both leads and polynyas. In leads grease ice forms in the open water, then is herded to the down-wind edge of the lead; in polynyas a Langmuir circulation herds the grease ice into long plumes parallel to the wind. In the laboratory we grow grease ice in a wave tank and measure its wave absorption properties for single-frequency, two-dimensional waves. On a large scale we find that the thickness of the grease ice, which increases away from the paddle, is determined by a balance between the wave-momentum flux and the free-surface tilt. On a small scale our photographs show that the crystals which make up the grease ice consist of discs measuring about 1 mm in diameter and 1–10 µm thick, which at low rates of shear sinter together into larger clumps yielding a viscosity increase. To measure this non-linear viscosity, we study the decay of wave amplitude between two critical distances measured inwards from the leading edge. The first occurs when the depth of grease ice exceeds k −1 where k is the wave number; the second further distance is a line of transition from liquid to solid behavior which we call the dead zone. Between these two distances the wave amplitude decays with a linear slope α , which increases as ( a 0 k ) 2 where a 0 is the wave amplitude in open water. Concurrent measurements of ice concentration show that it increases from values of 18–22% at the leading edge to a local maximum of 32–44% at the dead zone, while the values at the dead zone increase non-linearly with a 0 k . Finally, comparison of the observed α to that calculated from a yield-stress viscosity model shows if the yield-stress coefficient is proportional to the incident wave-momentum flux, the model predicts the observed α . |
format |
Article in Journal/Newspaper |
author |
Martin, Seelye Kauffman, Peter |
spellingShingle |
Martin, Seelye Kauffman, Peter A Field and Laboratory Study of Wave Damping by Grease Ice |
author_facet |
Martin, Seelye Kauffman, Peter |
author_sort |
Martin, Seelye |
title |
A Field and Laboratory Study of Wave Damping by Grease Ice |
title_short |
A Field and Laboratory Study of Wave Damping by Grease Ice |
title_full |
A Field and Laboratory Study of Wave Damping by Grease Ice |
title_fullStr |
A Field and Laboratory Study of Wave Damping by Grease Ice |
title_full_unstemmed |
A Field and Laboratory Study of Wave Damping by Grease Ice |
title_sort |
field and laboratory study of wave damping by grease ice |
publisher |
Cambridge University Press (CUP) |
publishDate |
1981 |
url |
http://dx.doi.org/10.1017/s0022143000015392 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000015392 |
long_lat |
ENVELOPE(-67.150,-67.150,-66.967,-66.967) |
geographic |
Langmuir |
geographic_facet |
Langmuir |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 27, issue 96, page 283-313 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000015392 |
container_title |
Journal of Glaciology |
container_volume |
27 |
container_issue |
96 |
container_start_page |
283 |
op_container_end_page |
313 |
_version_ |
1802646351243116544 |