the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 03 Aug 2023
Damaging viscous-plastic sea ice
Abstract. We implement a damage parametrization in the standard viscous-plastic sea ice model to disentangle its effect from model physics (visco-elastic or elasto-brittle vs. visco-plastic) on its ability to reproduce observed scaling laws of deformation. To this end, we compare scaling properties and multifractality of simulated divergence and shear strain rate (as proposed in SIREx1), with those derived from the RADARSAT Geophysical Processor System (RGPS). Results show that including a damage parametrization in the standard viscous-plastic model increases the spatial, but decreases temporal localization of simulated Linear Kinematic Features, and brings all spatial deformation rate statistics in line with observations from RGPS without the need to increase the mechanical shear strength of sea ice as recently proposed for lower resolution viscous-plastic sea ice models. In fact, including damage an healing timescale of th = 30 days and an increased mechanical strength unveil multifractal behavior that does not fit the theory. Therefore, a damage parametrization is a powerful tuning knob affecting the deformation statistics.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-1354', Jérôme Weiss, 12 Sep 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1354/egusphere-2023-1354-RC1-supplement.pdf
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AC3: 'Reply on RC1', Antoine Savard, 14 Dec 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1354/egusphere-2023-1354-AC3-supplement.pdf
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AC3: 'Reply on RC1', Antoine Savard, 14 Dec 2023
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RC2: 'Comment on egusphere-2023-1354', Anonymous Referee #2, 25 Oct 2023
This paper is a useful contribution because the authors have demonstrated the multifractal behavior the VP and a VP model modified to include damage can have (or in fact not have). While the model does not match observations there is discussion of how the model behaves that could help future investigators improve models of sea ice deformation. What is lacking is often a physical interpretation of the model behavior. While relationships are described mathematically, such as the differences in scaling exponents or departure from expected multifractal behavior, no context as to why this might be is given. Perhaps this is not possible to determine, however it would be useful insight.Overall I feel this contribution is valuable and should be published. Though I would caution readers to consider if multifractals are the best metric to validate simulated deformation or distinguish models. There are places where the authors can strenghten their argument as to why it is important to reproduce observed scaling behavior for sea ice deformation or linear kinematic features. The contribution of this paper in describing the model behavior with the mathematical language of multifractals is helpful in the conversation.General commentsThe deformation of sea ice is shown to be coupled in space and time, such that the scaling relationship in each varies depending on the sampling in the other. This means that when comparing a model with observations you have to account for this time or space sampling difference. How do you ensure that you are comparing scaling relationships for the same time or space sampling in the model and observations?It is a useful comment that even ad-hoc parameterization of heterogeneity in ice strength could improve representation of sea ice deformation. This jives with my personal experience where if I solve the VP model to full plastic equilibrium it is not possible to simulate LKFs unless you seed variability in ice strength randomly. Which is about as simple a parameterization as one can make! In the introduction a damage parameterization is introduced, and in the discussion this is compared to other parameterizations used in other models. It might help the reader to give a little information about how the parameterizations differ up front and why you choose to develop your own.Specific CommentsAbstract line 8: Grammatical error "an"Line 14: Is "ilks" a good word to use here?This is a stylistic comment that you can take or leave: I found the first paragraph of the introduction did not really guide me to what the content of the paper would be about. In general I would suggest the introduction could be more focused.Line 24: Typical floe sizes range from meters to 10s of kilometers. So saying floe size is 10km is factually incorrect. It is correct to mention that the data you are working with has this lower resolution, but incorrect to call it floe size.Line 30: "complex laws" This is overly general. I encourage you to be more specific. This is also where you could point out that unlike turbulence in water or air, the scaling relationships for sea ice deformation are coupled in space and time. There is also large differences in scaling exponents found for different years and seasons, so it would be good to comment on if you accounting for this or just using values found for a particular time period or region.Line 34: Why should a model of Arctic sea ice simulate LKFs?Line 51: Missing full stop.Line 163: Sea ice can diverge and weaken (through reduced area) in the VP model even when LKFs are not present.Line 205-210: I am curious, when you are creating a run with 10 random years how do you ensure there are not unphysical jumps in the wind forcing between years? Does this matter, given the spin up of ice drift is relatively fast compared to the wind speed change.Line 316: "soup-like" is a weird choice of word here. Also is there a missing label by the "2".Line 320: "simulation" => "simulations"Line 331: I believe the decay is log-linear not linear.Figure 3: It is not clear where the observations in the black line are from. Where do you describe the observations in the paper and how you calculate the deformation. Are the distributions for model and observations from the same time and region? It is only apparent later in the paper that you are only considering data from January 2002 (line 538). Which makes me think you need to improve details in your methodology.Line 378: "morally" is a weird word choice here.I could not check code and data availably because links were not provided.Citation: https://doi.org/
10.5194/egusphere-2023-1354-RC2 -
AC2: 'Reply on RC2', Antoine Savard, 14 Dec 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1354/egusphere-2023-1354-AC2-supplement.pdf
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AC2: 'Reply on RC2', Antoine Savard, 14 Dec 2023
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EC1: 'Comment on egusphere-2023-1354 by acting Editor', Daniel Feltham, 16 Nov 2023
The manuscript proposes a simple, but ad hoc and poorly physically justified, approach to modification of the ice strength in a popular sea ice rheology scheme. The purpose of this is to create a low-computational cost way to better simulate some of the scaling properties of deformation. It is interesting, though not especially surprising (as the authors note), that this enables capture of some of these scaling relations with such a simple treatment.
I am sympathy with the general approach taken and there is much in this paper that is of value. The ad hoc approach is obviously not ideal and raises important concerns over appropriate choice of timescales, but then the rheology that is being modified is also exceedingly ad hoc and has been in use for over 40 years. Clearly the authors are aiming for a no-cost, practical approach that can be easily implemented into existing modelling architectures.
Nonetheless, one of the reviewers raised very important points that must be taken into account. Particularly damage refers to reduction of the elasticity, not plastic ice strength. As an Editor, I view it as my job to prevent the propagation of terms that are likely to cause confusion and are at odds with existing and mature bodies of work. As a result, I will not accept this paper if the word damage is used in its current form.
If the authors wish to proceed with revisions then careful account should be taken of all the comments by the reviewers, with particularly full responses given if a recommendation is not followed. But I reiterate that an alternative language must be found to express the reduction in ice strength and the word damage removed from the paper and title. The obvious term that springs to my mind is plastic weakening, which is what I believe it actually is.
Citation: https://doi.org/10.5194/egusphere-2023-1354-EC1 -
AC1: 'Reply on EC1', Antoine Savard, 14 Dec 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1354/egusphere-2023-1354-AC1-supplement.pdf
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AC1: 'Reply on EC1', Antoine Savard, 14 Dec 2023
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-1354', Jérôme Weiss, 12 Sep 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1354/egusphere-2023-1354-RC1-supplement.pdf
-
AC3: 'Reply on RC1', Antoine Savard, 14 Dec 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1354/egusphere-2023-1354-AC3-supplement.pdf
-
AC3: 'Reply on RC1', Antoine Savard, 14 Dec 2023
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RC2: 'Comment on egusphere-2023-1354', Anonymous Referee #2, 25 Oct 2023
This paper is a useful contribution because the authors have demonstrated the multifractal behavior the VP and a VP model modified to include damage can have (or in fact not have). While the model does not match observations there is discussion of how the model behaves that could help future investigators improve models of sea ice deformation. What is lacking is often a physical interpretation of the model behavior. While relationships are described mathematically, such as the differences in scaling exponents or departure from expected multifractal behavior, no context as to why this might be is given. Perhaps this is not possible to determine, however it would be useful insight.Overall I feel this contribution is valuable and should be published. Though I would caution readers to consider if multifractals are the best metric to validate simulated deformation or distinguish models. There are places where the authors can strenghten their argument as to why it is important to reproduce observed scaling behavior for sea ice deformation or linear kinematic features. The contribution of this paper in describing the model behavior with the mathematical language of multifractals is helpful in the conversation.General commentsThe deformation of sea ice is shown to be coupled in space and time, such that the scaling relationship in each varies depending on the sampling in the other. This means that when comparing a model with observations you have to account for this time or space sampling difference. How do you ensure that you are comparing scaling relationships for the same time or space sampling in the model and observations?It is a useful comment that even ad-hoc parameterization of heterogeneity in ice strength could improve representation of sea ice deformation. This jives with my personal experience where if I solve the VP model to full plastic equilibrium it is not possible to simulate LKFs unless you seed variability in ice strength randomly. Which is about as simple a parameterization as one can make! In the introduction a damage parameterization is introduced, and in the discussion this is compared to other parameterizations used in other models. It might help the reader to give a little information about how the parameterizations differ up front and why you choose to develop your own.Specific CommentsAbstract line 8: Grammatical error "an"Line 14: Is "ilks" a good word to use here?This is a stylistic comment that you can take or leave: I found the first paragraph of the introduction did not really guide me to what the content of the paper would be about. In general I would suggest the introduction could be more focused.Line 24: Typical floe sizes range from meters to 10s of kilometers. So saying floe size is 10km is factually incorrect. It is correct to mention that the data you are working with has this lower resolution, but incorrect to call it floe size.Line 30: "complex laws" This is overly general. I encourage you to be more specific. This is also where you could point out that unlike turbulence in water or air, the scaling relationships for sea ice deformation are coupled in space and time. There is also large differences in scaling exponents found for different years and seasons, so it would be good to comment on if you accounting for this or just using values found for a particular time period or region.Line 34: Why should a model of Arctic sea ice simulate LKFs?Line 51: Missing full stop.Line 163: Sea ice can diverge and weaken (through reduced area) in the VP model even when LKFs are not present.Line 205-210: I am curious, when you are creating a run with 10 random years how do you ensure there are not unphysical jumps in the wind forcing between years? Does this matter, given the spin up of ice drift is relatively fast compared to the wind speed change.Line 316: "soup-like" is a weird choice of word here. Also is there a missing label by the "2".Line 320: "simulation" => "simulations"Line 331: I believe the decay is log-linear not linear.Figure 3: It is not clear where the observations in the black line are from. Where do you describe the observations in the paper and how you calculate the deformation. Are the distributions for model and observations from the same time and region? It is only apparent later in the paper that you are only considering data from January 2002 (line 538). Which makes me think you need to improve details in your methodology.Line 378: "morally" is a weird word choice here.I could not check code and data availably because links were not provided.Citation: https://doi.org/
10.5194/egusphere-2023-1354-RC2 -
AC2: 'Reply on RC2', Antoine Savard, 14 Dec 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1354/egusphere-2023-1354-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Antoine Savard, 14 Dec 2023
-
EC1: 'Comment on egusphere-2023-1354 by acting Editor', Daniel Feltham, 16 Nov 2023
The manuscript proposes a simple, but ad hoc and poorly physically justified, approach to modification of the ice strength in a popular sea ice rheology scheme. The purpose of this is to create a low-computational cost way to better simulate some of the scaling properties of deformation. It is interesting, though not especially surprising (as the authors note), that this enables capture of some of these scaling relations with such a simple treatment.
I am sympathy with the general approach taken and there is much in this paper that is of value. The ad hoc approach is obviously not ideal and raises important concerns over appropriate choice of timescales, but then the rheology that is being modified is also exceedingly ad hoc and has been in use for over 40 years. Clearly the authors are aiming for a no-cost, practical approach that can be easily implemented into existing modelling architectures.
Nonetheless, one of the reviewers raised very important points that must be taken into account. Particularly damage refers to reduction of the elasticity, not plastic ice strength. As an Editor, I view it as my job to prevent the propagation of terms that are likely to cause confusion and are at odds with existing and mature bodies of work. As a result, I will not accept this paper if the word damage is used in its current form.
If the authors wish to proceed with revisions then careful account should be taken of all the comments by the reviewers, with particularly full responses given if a recommendation is not followed. But I reiterate that an alternative language must be found to express the reduction in ice strength and the word damage removed from the paper and title. The obvious term that springs to my mind is plastic weakening, which is what I believe it actually is.
Citation: https://doi.org/10.5194/egusphere-2023-1354-EC1 -
AC1: 'Reply on EC1', Antoine Savard, 14 Dec 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1354/egusphere-2023-1354-AC1-supplement.pdf
-
AC1: 'Reply on EC1', Antoine Savard, 14 Dec 2023
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Antoine Savard
Bruno Tremblay
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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(4114 KB) - Metadata XML