the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 24 Feb 2023
The porosity effect on the mechanical properties of summer sea ice in the Arctic
Abstract. To investigate the mechanical properties of sea ice in the current summer Arctic, two ice blocks were lifted using ship crane during an Arctic expedition in the summer of 2021. Examination of ice crystal structure showed a granular ice layer at the top underlain by a columnar ice layer. Sea ice samples were then machined from the ice blocks for mechanical experiments performed in the laboratory. Three-point bending tests were conducted at ice temperatures of −12 to −3 ºC, and uniaxial compressive strength tests were conducted at ice temperatures of −8 to −3 ºC with a strain rate range of 10−6–10−2 s−1. The ice density and salinity of each sample were measured to determine brine and gas volume fraction as well as porosity. Results showed that sea ice flexural strength decreased with increasing porosity, but did not change with varying brine or gas volume fractions. A parameterization was proposed to relate sea ice flexural strength to porosity. The sea ice strain modulus was also independent on porosity and volume fractions of gas and brine. The uniaxial compressive strength decreased with increasing porosity at both ductile and brittle strain rate regimes. Furthermore, three-dimensional surfaces were obtained to depict the sea ice uniaxial compressive strength varying with porosity and strain rate, based on which the transition strain rate from ductile to brittle behaviors was determined. It was found that the transition strain rate decreased with increasing porosity. Comparisons with previous studies on sea ice strength showed that the previously reported equations for sea ice flexural strength and strain modulus did not agree with the measured data. Compared with the strength calculated using early reported sea ice porosity, the flexural strength and uniaxial compressive strength of summer Arctic sea ice decreased in recent decades, which probably brings positive feedback to the Arctic navigation.
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RC1: 'Comment on tc-2023-31', Anonymous Referee #1, 08 Mar 2023
I only have one comment and it's regarding the title. There is no such thing as 'summer sea ice'. Sea ice can form at any time of the year, which is usually not in the summer. A more appropriate title: Effect of porosity on the mechanical properties of Arctic sea ice in the summer
Citation: https://doi.org/10.5194/tc-2023-31-RC1 -
AC1: 'Reply on RC1', Qingkai Wang, 09 Jun 2023
We appreciate warmly for the reviewer’s earnest work. The comment is constructive, and we will revise the title as the reviewer suggested.
Citation: https://doi.org/10.5194/tc-2023-31-AC1
-
AC1: 'Reply on RC1', Qingkai Wang, 09 Jun 2023
-
RC2: 'Comment on tc-2023-31', Anonymous Referee #2, 27 Mar 2023
Inveitigation on ice properties is valuable to the assessment of ship navigation in ice-covered waters. This work is quite important and practical to engineering application. The manuscript is well written and suggested to publish. I have a comment on Fig.12. It shows that the measured data are a little scattered from the varying trend line. More explainations are expected to improve condifence level of exisitng data.
Citation: https://doi.org/10.5194/tc-2023-31-RC2 - AC2: 'Reply on RC2', Qingkai Wang, 09 Jun 2023
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RC3: 'Comment on tc-2023-31', Paul Barrette, 01 Apr 2023
General comments
The authors present an interesting account, albeit not new (many such studies have been done in the past), of the outcome of mechanical testing on sea ice. They make an instructive comparison between their data from sea ice they collected from the North, and the outcome of earlier studies by other investigators. One significant weakness I see in this paper is that it is based entirely on one block extracted at two sites, i.e., two blocks. Firstly, one block may or may not be representative of the site itself. Secondly, two sites are not likely representative of the Central Arctic as a whole. There is also a lot of scatter in their data, which adds limitations to the value of their conclusions. That, in my view, is ground for rejecting this paper. However, the exercise is worth bringing up, as long as the authors carefully elaborate on these limitations inside its own section (which could be entitled 'Limitations of this study'), in the conclusion and in the abstract. Overall, the English is good, but can be improved in many places. Much of the suggested improvements are the outcome of carelessness (more so than non-familiarity with English).
Specific comments
- The rationale for this paper seems to be that past mechanical testing of sea ice was representative of colder ice, and not of today’s warmer temperatures in the North. Is that what the authors mean in the introduction? If so, the authors may like to clarify this in their paper.
- There is a large amount of work in the past English literature (in other languages also, no doubt) dedicated to the mechanical properties of sea ice. The authors provide three citations on line 33. They should point out those are only examples. For instance, simply state, “...was developed rapidly in the Arctic regions (g., Kovacs, 1997; Timco and Frederking, 1990; Timco and O’Brien, 1994), i.e., add “e.g.”
- The authors should be careful in not confusing their two samples of ice with the two sites. I suggest they refer to the S1 ‘sample’, not the S1 ‘site’. Alternatively, include a statement at the beginning of section 2, like “In what follows, we will assume the two samples are representative of both sites.”
- How was the modulus determined for the compressive tests? The initial tangential response of the stress-strain relationship?
- The 3-point flexural test is valid only if the fracture occurs exactly at the point where it is loaded. Otherwise equation (1) is not valid. This is why a four-point test configuration is preferred, as the fracture plane can then occur anywhere between the two upper points.
- A short description of how the beam failed and what the maximum load was should be provided for both the flexural and compressive tests. It is easy to produce numbers, but the reader would benefit from some idea of how these numbers were obtained. A representative photograph of each would be desirable.
- Examples of stress-strain response should be provided in this manuscript, to accompany the description. Also, to better explain was is meant by ‘ductile’ vs ‘brittle’ behavior. Also, what the ‘transition’ strain rate is. The text is insufficient to clearly show that.
- In section 4.1.1, the discussion on the uniaxial strength, the reader is led to believe that the outcome of this study should be considered ‘correct’, and thus others that do not match that outcome would need to be adjusted. For instance, with this sentence: “While for vertically loaded columnar ice, both estimations by Timco and Frederking (1990) and Wang et al. (2022) overestimated the measured strength.” Is that the intention? The reason I ask is that, the analysis in this manuscript is only on two ice blocks, which is very weak basis. The authors should rephrase their text to clarify.
- Similarly to the point above about section 4.1.1, but this one about section 4.1.2 regarding flexural strength. Consider the authors’ statement at line 344: “The overestimation of Timco and O’Brien (1994) than [sic] our measured strength confirmed that flexural strength more accurately depended upon the porosity, especially for warm sea ice”. Later on also (e.g., line 372: “Karulina et al. (2019) underestimated our measured data”). This seems to indicate that the two ice blocks used in this study, and their analysis thereof, are sufficient to define a firm basis against which all other studies should be compared. This is surprising, given that Timco and O’Brien include tests over all temperature ranges, including those next to melting. The authors should correct the text to clarify their position: do they really think their data (on two ice blocks) are sufficient to draw such conclusions?
- Abstract: Please ensure it is reviewed and made compatible with the final version of this manuscript.
Technical corrections and suggestions
Below is a listing of improvements the author might wish to incorporate in their manuscript.
**************
L27: Do not use “ice-infested”. That term was used in the past, but since then, it has become politically incorrect (ice is not an infestation) and utterly anthropocentric. Consider instead “...in icy waters” or “in frozen waters”, ...
L27: “...which causes excessive and uneconomic outcomes applying the design codes”. Not clear or clumsy. Do you mean the design codes may no longer be adequate?
L30: commonly used (with a hyphen).
L32: “...oil exploration was extensive in the Arctic regions”.
L34: Delete ‘although’.
L35: ‘is flourishing’, not ‘are flourishing’.
L36: Replace ‘sea ice mechanics is’ with ‘the mechanical properties of ice are’
L44: Replace ‘cause a less content of brine gas’ with ‘increase the amount of gas relative to the brine content’
L45-46: Proposed rephrase: ‘Sea ice modulus has received relatively little attention’.
L53: Suggested rephrase: ‘A question that arises consequently is whether or not the equations...’
L56: Replace ‘provided’ with ‘showed’.
L57: ‘...in response to global warming...’
L58: Replace ‘...decreased than decades ago...‘ with ‘...decreased more than they did a few decades ago’.
L63: ‘...which could help better understand the response of Arctic sea ice...’
L65: Replace ‘the domestic laboratory’ with ‘our cold room facilities in China’.
L66: ‘we present the results of flexural strength,...’. You should use the present tense, not the past, for what is described in this paper. Another example on L68 – equations ARE given, not were given. Please correct throughout your manuscript. Why the past? It is currently in the paper!
L70: design construction, ... in support of offshore activities in the Arctic during the summer.
Section 2.1: At the beginning of this section, state the amount of time the voyage required (two months? From when to when?)
L75: Unclear whether the ice blocks were from the level ice, which you mention one line before, or pack ice. These are two different zones. Please clarify.
L77: ‘That ice at both sites WAS covered...’
L82: ‘... IT WAS DETERMINED THAT the ice in the Central Arctic Ocean...’
L83: Clarify this: ‘experienced 40 day melt’. What do you mean?
L84: ‘......showed no cracks in the ice. However, the top had undergone some damage due to the interaction with the ship hull during its retrieval.’
L85: Replace ‘archived carefully using plastic bags’ with ‘put inside plastic bags’.
L86: ‘...were stored in a cold room at -20oC’. No need to mention solar radiation (it’s in a cold room).
L86-87: Remove ‘at home’, move ‘2 month expedition’ to the beginning of section 2.1.
L94: ‘... observing THEM under...’ – ‘...of ice blocks FROM S1 and S2 sites...’
L97: ‘...because the thin sections INADVERTENTLY melted after preparation during a defrosting event in the cold room...’
L98: ‘Based on the horizontal sections, it is inferred that the top 35cm of ice on that sample was made of granular ice.”
L100: ‘The columnar ice crystals were seen to grow and extend downward from the granular ice,...’
At this point, I am going to stop, as this was getting too labor-intensive. I am including a copy of the annotated manuscript. I would encourage the authors to give those annotations due consideration.
- AC3: 'Reply on RC3', Qingkai Wang, 09 Jun 2023
-
AC5: 'Reply on RC3', Qingkai Wang, 09 Jun 2023
Dear Prof. Paul Barrette,
Please forgive us for our oversight in signing someone else's name in the previous reply.
They are indeed our responses to your comments.
Best wishes,
Qingkai Wang
Citation: https://doi.org/10.5194/tc-2023-31-AC5
-
RC4: 'Comment on tc-2023-31', Matthias Steiner, 03 Apr 2023
The authors present an interesting study addressing changes in the mechanical properties of Arctic sea ice associated with the increasing temperatures in this region. Although such investigations are relevant for various applications the present study has several weak points:
- The structure of the manuscript, single paragraphs yet also some sentences need to be improved. In the current version, the manuscript is not always easy to follow as the flow is repeatedly interrupted.
- The different sections/parts of the manuscript are not always connected, i.e., the red thread is missing. This is particularly evident for the Results and the Discussion section.
- The sample size is critically small. Two samples are not sufficient to conclude that the presented empirical relationship is superior to other well-established (empirical) models/relationships obtained for larger data sets.
- References underpinning certain statements are missing in some parts of the manuscript.
- The authors repeatedly fail to communicate results and the associated interpretations/findings in a quantitative way.
- In general, the English is sufficient, yet the usage of the English language should be improved to make the manuscript more accessible.
In the current version, the manuscript is not acceptable for publication in The Cryosphere but requires major revisions addressing the weak points/limitations listed above. Some general suggestions:- The authors should establish a better story to adequately present this study and restructure the manuscript accordingly.
- A more thorough appreciation of existing literature is required.
- Provide enhanced formulations in the text by taking into account formulations in existing studies.
- Address the limitations/shortcomings of the study (in comparison to existing literature).
Additionally, I provide detailed comments and suggestions in the annotated copy of the manuscript attached here.
- AC4: 'Reply on RC4', Qingkai Wang, 09 Jun 2023
Status: closed
-
RC1: 'Comment on tc-2023-31', Anonymous Referee #1, 08 Mar 2023
I only have one comment and it's regarding the title. There is no such thing as 'summer sea ice'. Sea ice can form at any time of the year, which is usually not in the summer. A more appropriate title: Effect of porosity on the mechanical properties of Arctic sea ice in the summer
Citation: https://doi.org/10.5194/tc-2023-31-RC1 -
AC1: 'Reply on RC1', Qingkai Wang, 09 Jun 2023
We appreciate warmly for the reviewer’s earnest work. The comment is constructive, and we will revise the title as the reviewer suggested.
Citation: https://doi.org/10.5194/tc-2023-31-AC1
-
AC1: 'Reply on RC1', Qingkai Wang, 09 Jun 2023
-
RC2: 'Comment on tc-2023-31', Anonymous Referee #2, 27 Mar 2023
Inveitigation on ice properties is valuable to the assessment of ship navigation in ice-covered waters. This work is quite important and practical to engineering application. The manuscript is well written and suggested to publish. I have a comment on Fig.12. It shows that the measured data are a little scattered from the varying trend line. More explainations are expected to improve condifence level of exisitng data.
Citation: https://doi.org/10.5194/tc-2023-31-RC2 - AC2: 'Reply on RC2', Qingkai Wang, 09 Jun 2023
-
RC3: 'Comment on tc-2023-31', Paul Barrette, 01 Apr 2023
General comments
The authors present an interesting account, albeit not new (many such studies have been done in the past), of the outcome of mechanical testing on sea ice. They make an instructive comparison between their data from sea ice they collected from the North, and the outcome of earlier studies by other investigators. One significant weakness I see in this paper is that it is based entirely on one block extracted at two sites, i.e., two blocks. Firstly, one block may or may not be representative of the site itself. Secondly, two sites are not likely representative of the Central Arctic as a whole. There is also a lot of scatter in their data, which adds limitations to the value of their conclusions. That, in my view, is ground for rejecting this paper. However, the exercise is worth bringing up, as long as the authors carefully elaborate on these limitations inside its own section (which could be entitled 'Limitations of this study'), in the conclusion and in the abstract. Overall, the English is good, but can be improved in many places. Much of the suggested improvements are the outcome of carelessness (more so than non-familiarity with English).
Specific comments
- The rationale for this paper seems to be that past mechanical testing of sea ice was representative of colder ice, and not of today’s warmer temperatures in the North. Is that what the authors mean in the introduction? If so, the authors may like to clarify this in their paper.
- There is a large amount of work in the past English literature (in other languages also, no doubt) dedicated to the mechanical properties of sea ice. The authors provide three citations on line 33. They should point out those are only examples. For instance, simply state, “...was developed rapidly in the Arctic regions (g., Kovacs, 1997; Timco and Frederking, 1990; Timco and O’Brien, 1994), i.e., add “e.g.”
- The authors should be careful in not confusing their two samples of ice with the two sites. I suggest they refer to the S1 ‘sample’, not the S1 ‘site’. Alternatively, include a statement at the beginning of section 2, like “In what follows, we will assume the two samples are representative of both sites.”
- How was the modulus determined for the compressive tests? The initial tangential response of the stress-strain relationship?
- The 3-point flexural test is valid only if the fracture occurs exactly at the point where it is loaded. Otherwise equation (1) is not valid. This is why a four-point test configuration is preferred, as the fracture plane can then occur anywhere between the two upper points.
- A short description of how the beam failed and what the maximum load was should be provided for both the flexural and compressive tests. It is easy to produce numbers, but the reader would benefit from some idea of how these numbers were obtained. A representative photograph of each would be desirable.
- Examples of stress-strain response should be provided in this manuscript, to accompany the description. Also, to better explain was is meant by ‘ductile’ vs ‘brittle’ behavior. Also, what the ‘transition’ strain rate is. The text is insufficient to clearly show that.
- In section 4.1.1, the discussion on the uniaxial strength, the reader is led to believe that the outcome of this study should be considered ‘correct’, and thus others that do not match that outcome would need to be adjusted. For instance, with this sentence: “While for vertically loaded columnar ice, both estimations by Timco and Frederking (1990) and Wang et al. (2022) overestimated the measured strength.” Is that the intention? The reason I ask is that, the analysis in this manuscript is only on two ice blocks, which is very weak basis. The authors should rephrase their text to clarify.
- Similarly to the point above about section 4.1.1, but this one about section 4.1.2 regarding flexural strength. Consider the authors’ statement at line 344: “The overestimation of Timco and O’Brien (1994) than [sic] our measured strength confirmed that flexural strength more accurately depended upon the porosity, especially for warm sea ice”. Later on also (e.g., line 372: “Karulina et al. (2019) underestimated our measured data”). This seems to indicate that the two ice blocks used in this study, and their analysis thereof, are sufficient to define a firm basis against which all other studies should be compared. This is surprising, given that Timco and O’Brien include tests over all temperature ranges, including those next to melting. The authors should correct the text to clarify their position: do they really think their data (on two ice blocks) are sufficient to draw such conclusions?
- Abstract: Please ensure it is reviewed and made compatible with the final version of this manuscript.
Technical corrections and suggestions
Below is a listing of improvements the author might wish to incorporate in their manuscript.
**************
L27: Do not use “ice-infested”. That term was used in the past, but since then, it has become politically incorrect (ice is not an infestation) and utterly anthropocentric. Consider instead “...in icy waters” or “in frozen waters”, ...
L27: “...which causes excessive and uneconomic outcomes applying the design codes”. Not clear or clumsy. Do you mean the design codes may no longer be adequate?
L30: commonly used (with a hyphen).
L32: “...oil exploration was extensive in the Arctic regions”.
L34: Delete ‘although’.
L35: ‘is flourishing’, not ‘are flourishing’.
L36: Replace ‘sea ice mechanics is’ with ‘the mechanical properties of ice are’
L44: Replace ‘cause a less content of brine gas’ with ‘increase the amount of gas relative to the brine content’
L45-46: Proposed rephrase: ‘Sea ice modulus has received relatively little attention’.
L53: Suggested rephrase: ‘A question that arises consequently is whether or not the equations...’
L56: Replace ‘provided’ with ‘showed’.
L57: ‘...in response to global warming...’
L58: Replace ‘...decreased than decades ago...‘ with ‘...decreased more than they did a few decades ago’.
L63: ‘...which could help better understand the response of Arctic sea ice...’
L65: Replace ‘the domestic laboratory’ with ‘our cold room facilities in China’.
L66: ‘we present the results of flexural strength,...’. You should use the present tense, not the past, for what is described in this paper. Another example on L68 – equations ARE given, not were given. Please correct throughout your manuscript. Why the past? It is currently in the paper!
L70: design construction, ... in support of offshore activities in the Arctic during the summer.
Section 2.1: At the beginning of this section, state the amount of time the voyage required (two months? From when to when?)
L75: Unclear whether the ice blocks were from the level ice, which you mention one line before, or pack ice. These are two different zones. Please clarify.
L77: ‘That ice at both sites WAS covered...’
L82: ‘... IT WAS DETERMINED THAT the ice in the Central Arctic Ocean...’
L83: Clarify this: ‘experienced 40 day melt’. What do you mean?
L84: ‘......showed no cracks in the ice. However, the top had undergone some damage due to the interaction with the ship hull during its retrieval.’
L85: Replace ‘archived carefully using plastic bags’ with ‘put inside plastic bags’.
L86: ‘...were stored in a cold room at -20oC’. No need to mention solar radiation (it’s in a cold room).
L86-87: Remove ‘at home’, move ‘2 month expedition’ to the beginning of section 2.1.
L94: ‘... observing THEM under...’ – ‘...of ice blocks FROM S1 and S2 sites...’
L97: ‘...because the thin sections INADVERTENTLY melted after preparation during a defrosting event in the cold room...’
L98: ‘Based on the horizontal sections, it is inferred that the top 35cm of ice on that sample was made of granular ice.”
L100: ‘The columnar ice crystals were seen to grow and extend downward from the granular ice,...’
At this point, I am going to stop, as this was getting too labor-intensive. I am including a copy of the annotated manuscript. I would encourage the authors to give those annotations due consideration.
- AC3: 'Reply on RC3', Qingkai Wang, 09 Jun 2023
-
AC5: 'Reply on RC3', Qingkai Wang, 09 Jun 2023
Dear Prof. Paul Barrette,
Please forgive us for our oversight in signing someone else's name in the previous reply.
They are indeed our responses to your comments.
Best wishes,
Qingkai Wang
Citation: https://doi.org/10.5194/tc-2023-31-AC5
-
RC4: 'Comment on tc-2023-31', Matthias Steiner, 03 Apr 2023
The authors present an interesting study addressing changes in the mechanical properties of Arctic sea ice associated with the increasing temperatures in this region. Although such investigations are relevant for various applications the present study has several weak points:
- The structure of the manuscript, single paragraphs yet also some sentences need to be improved. In the current version, the manuscript is not always easy to follow as the flow is repeatedly interrupted.
- The different sections/parts of the manuscript are not always connected, i.e., the red thread is missing. This is particularly evident for the Results and the Discussion section.
- The sample size is critically small. Two samples are not sufficient to conclude that the presented empirical relationship is superior to other well-established (empirical) models/relationships obtained for larger data sets.
- References underpinning certain statements are missing in some parts of the manuscript.
- The authors repeatedly fail to communicate results and the associated interpretations/findings in a quantitative way.
- In general, the English is sufficient, yet the usage of the English language should be improved to make the manuscript more accessible.
In the current version, the manuscript is not acceptable for publication in The Cryosphere but requires major revisions addressing the weak points/limitations listed above. Some general suggestions:- The authors should establish a better story to adequately present this study and restructure the manuscript accordingly.
- A more thorough appreciation of existing literature is required.
- Provide enhanced formulations in the text by taking into account formulations in existing studies.
- Address the limitations/shortcomings of the study (in comparison to existing literature).
Additionally, I provide detailed comments and suggestions in the annotated copy of the manuscript attached here.
- AC4: 'Reply on RC4', Qingkai Wang, 09 Jun 2023
Data sets
The results of flexural and uniaxial compressive tests of summer Arctic sea ice Qingkai Wang, Yubo Liu, Peng Lu, Zhijun Li https://doi.org/10.5281/zenodo.7536404
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