Continuous in situ measurements of anchor ice formation, growth, and release
In northern rivers, turbulent water becomes supercooled (i.e. cooled to slightly below the freezing point) when exposed to freezing air temperatures. In supercooled turbulent water, frazil (small ice disks) crystals are generated in the water column, and anchor ice starts to form on the bed. Two anc...
Published in: | The Cryosphere |
---|---|
Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2021
|
Subjects: | |
Online Access: | https://doi.org/10.5194/tc-15-49-2021 https://doaj.org/article/fa0ff57929794309ad0f7369bc457bd5 |
id |
ftdoajarticles:oai:doaj.org/article:fa0ff57929794309ad0f7369bc457bd5 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:fa0ff57929794309ad0f7369bc457bd5 2023-05-15T18:32:27+02:00 Continuous in situ measurements of anchor ice formation, growth, and release T. R. Ghobrial M. R. Loewen 2021-01-01T00:00:00Z https://doi.org/10.5194/tc-15-49-2021 https://doaj.org/article/fa0ff57929794309ad0f7369bc457bd5 EN eng Copernicus Publications https://tc.copernicus.org/articles/15/49/2021/tc-15-49-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-49-2021 1994-0416 1994-0424 https://doaj.org/article/fa0ff57929794309ad0f7369bc457bd5 The Cryosphere, Vol 15, Pp 49-67 (2021) Environmental sciences GE1-350 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.5194/tc-15-49-2021 2022-12-31T12:03:59Z In northern rivers, turbulent water becomes supercooled (i.e. cooled to slightly below the freezing point) when exposed to freezing air temperatures. In supercooled turbulent water, frazil (small ice disks) crystals are generated in the water column, and anchor ice starts to form on the bed. Two anchor ice formation mechanisms have been reported in the literature: either by the accumulation of suspended frazil particles, which are adhesive (sticky) in nature, on the riverbed or by in situ growth of ice crystals on the bed material. Once anchor ice has formed on the bed, the accumulation typically continues to grow (due to either further frazil accumulation and/or crystal growth) until release occurs due to mechanical (shear force by the flow or buoyancy of the accumulation) or thermal (warming of the water column which weakens the ice-substrate bond) forcing or a combination of the two. There have been a number of detailed laboratory studies of anchor ice reported in the literature, but very few field measurements of anchor ice processes have been reported. These measurements have relied on either sampling anchor ice accumulations from the riverbed or qualitatively describing the observed formation and release. In this study, a custom-built imaging system (camera and lighting) was developed to capture high-resolution digital images of anchor ice formation and release on the riverbed. A total of six anchor ice events were successfully captured in the time-lapse images, and for the first time, the different initiation, growth, and release mechanisms were measured in the field. Four stages of the anchor ice cycle were identified: Stage 1: initiation by in situ crystal growth; Stage 2: transitional phase; Stage 3: linear growth; and Stage 4: release phase. Anchor ice initiation due to in situ growth was observed in three events, and in the remainder, the accumulation appeared to be initiated by frazil deposition. The Stage 1 growth rates ranged from 1.3 to 2.0 cm/h, and the Stage 2 and 3 growth rates varied from 0.3 ... Article in Journal/Newspaper The Cryosphere Directory of Open Access Journals: DOAJ Articles The Cryosphere 15 1 49 67 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 T. R. Ghobrial M. R. Loewen Continuous in situ measurements of anchor ice formation, growth, and release |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
In northern rivers, turbulent water becomes supercooled (i.e. cooled to slightly below the freezing point) when exposed to freezing air temperatures. In supercooled turbulent water, frazil (small ice disks) crystals are generated in the water column, and anchor ice starts to form on the bed. Two anchor ice formation mechanisms have been reported in the literature: either by the accumulation of suspended frazil particles, which are adhesive (sticky) in nature, on the riverbed or by in situ growth of ice crystals on the bed material. Once anchor ice has formed on the bed, the accumulation typically continues to grow (due to either further frazil accumulation and/or crystal growth) until release occurs due to mechanical (shear force by the flow or buoyancy of the accumulation) or thermal (warming of the water column which weakens the ice-substrate bond) forcing or a combination of the two. There have been a number of detailed laboratory studies of anchor ice reported in the literature, but very few field measurements of anchor ice processes have been reported. These measurements have relied on either sampling anchor ice accumulations from the riverbed or qualitatively describing the observed formation and release. In this study, a custom-built imaging system (camera and lighting) was developed to capture high-resolution digital images of anchor ice formation and release on the riverbed. A total of six anchor ice events were successfully captured in the time-lapse images, and for the first time, the different initiation, growth, and release mechanisms were measured in the field. Four stages of the anchor ice cycle were identified: Stage 1: initiation by in situ crystal growth; Stage 2: transitional phase; Stage 3: linear growth; and Stage 4: release phase. Anchor ice initiation due to in situ growth was observed in three events, and in the remainder, the accumulation appeared to be initiated by frazil deposition. The Stage 1 growth rates ranged from 1.3 to 2.0 cm/h, and the Stage 2 and 3 growth rates varied from 0.3 ... |
format |
Article in Journal/Newspaper |
author |
T. R. Ghobrial M. R. Loewen |
author_facet |
T. R. Ghobrial M. R. Loewen |
author_sort |
T. R. Ghobrial |
title |
Continuous in situ measurements of anchor ice formation, growth, and release |
title_short |
Continuous in situ measurements of anchor ice formation, growth, and release |
title_full |
Continuous in situ measurements of anchor ice formation, growth, and release |
title_fullStr |
Continuous in situ measurements of anchor ice formation, growth, and release |
title_full_unstemmed |
Continuous in situ measurements of anchor ice formation, growth, and release |
title_sort |
continuous in situ measurements of anchor ice formation, growth, and release |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-49-2021 https://doaj.org/article/fa0ff57929794309ad0f7369bc457bd5 |
genre |
The Cryosphere |
genre_facet |
The Cryosphere |
op_source |
The Cryosphere, Vol 15, Pp 49-67 (2021) |
op_relation |
https://tc.copernicus.org/articles/15/49/2021/tc-15-49-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-49-2021 1994-0416 1994-0424 https://doaj.org/article/fa0ff57929794309ad0f7369bc457bd5 |
op_doi |
https://doi.org/10.5194/tc-15-49-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
1 |
container_start_page |
49 |
op_container_end_page |
67 |
_version_ |
1766216565601075200 |