Brief communication: Intercomparison study reveals pathways for improving the representation of sea-ice biogeochemistry in models

Tedesco, Letizia; Castellani, Giulia; Duarte, Pedro; Jin, Meibing; Moreau, Sebastien; Mortenson, Eric; Saenz, Benjamin Tobey; Steiner, Nadja; Vancoppenolle, Martin

doi:10.5194/egusphere-2025-1107

Preprints

https://doi.org/10.5194/egusphere-2025-1107

Preprints

15 Apr 2025

| 15 Apr 2025

Brief communication: Intercomparison study reveals pathways for improving the representation of sea-ice biogeochemistry in models

Letizia Tedesco, Giulia Castellani, Pedro Duarte, Meibing Jin, Sebastien Moreau, Eric Mortenson, Benjamin Tobey Saenz, Nadja Steiner, and Martin Vancoppenolle

Abstract. Sea-ice biogeochemical models are key to understanding polar marine ecosystems. We present an intercomparison of six one-dimensional sea-ice biogeochemical models, assessing their ability to simulate algal phenology and nutrient dynamics by comparing them with sea-ice physical-biogeochemical data collected during the N-ICE2015 expedition. While no model fully captured observed bloom dynamics without tuning, adjustments improved biomass simulations but had a limited impact on nutrient representation. Variability in tuning strategies underscores key knowledge gaps and the need for further model development in more harmonised ways. Our findings can inform future efforts to enhance the reliability and predictive capacity of sea-ice biogeochemical models.

Received: 07 Mar 2025 – Discussion started: 15 Apr 2025

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.

Download & links

Preprint (PDF, 935 KB)

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.
Preprint (935 KB)

Download & links

The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Journal article(s) based on this preprint

28 Jan 2026

Brief communication: Intercomparison study reveals pathways for improving the representation of sea-ice biogeochemistry in models

Letizia Tedesco, Giulia Castellani, Pedro Duarte, Meibing Jin, Sebastien Moreau, Eric Mortenson, Benjamin Tobey Saenz, Nadja Steiner, and Martin Vancoppenolle

The Cryosphere, 20, 723–736, https://doi.org/10.5194/tc-20-723-2026,https://doi.org/10.5194/tc-20-723-2026, 2026

Short summary

Letizia Tedesco, Giulia Castellani, Pedro Duarte, Meibing Jin, Sebastien Moreau, Eric Mortenson, Benjamin Tobey Saenz, Nadja Steiner, and Martin Vancoppenolle

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2025-1107', Anonymous Referee #1, 12 May 2025

Review of Tedesco et al. “Brief communication: Intercomparison study reveals pathways for improving the representation of sea-ice biogeochemistry in models”

The manuscript presents an intercomparison between 6 one-dimensional sea-ice biogeochemical models. Models were forced with the same atmospheric and oceanic data from a time series of observations from a refrozen lead and validated with associated chlorophyll a, nitrate, and silicate data. Models were first run with their default parameterizations, and then teams were asked to tune their models to best match the observations. The authors found that with tuning, most models were able to reproduce chlorophyll a timing and concentration but not so much nutrients. Model teams also differed in their tuning choices.
I think the exercise of model intercomparison is valuable and this is a timely moment to do one for sea-ice BGC, as the number of models has been increasing. I also think the exercise is well-structured and shows significant effort on the part of many people in independently running and tuning the models with the same set of forcings (not a given in other model intercomparisons) in order to reveal a process understanding. As the manuscript is currently written, however, it is difficult for a reader outside of the group to gain much insight or understanding from the exercise. I know this is meant to be a “brief communication”, but I think it deserves a far more detailed paper, for which the changes would probably be considered major revisions.
1.) My main concern surrounds the brief treatment of A) describing what the models are doing and B) usefully synthesizing the outcomes. The manuscript sets up its goal as wanting to gain increased process understanding (rather than simply comparing model outputs, which is more the goal of intercomparisons like Watanabe et al. 2019 that they cite) but I did not feel like it went beyond listing individual model tuning in a way that informed my understanding of the sea-ice ecosystem.
What were key parameter values before/after tuning? Table 2/the list in L178-182 seems like it should be the heart of the Discussion but I didn’t know why modeling teams chose to make those tuning adjustments, whether any choices were specific to model design or previous parameterization, or how model outcomes might be tied to their design. E.g., Can anything be said about models that are BL vs. DE or quota vs. Redfield? Does increased model complexity improve match to observations? Were the tuning changes still within reasonable values for BGC processes, or do they suggest that model physics might be off? What would this work mean for future sea-ice researchers, especially those adjacent to the author group? Lastly, depending on the direction of Discussion, it may be useful to include more model description than currently exists in the Methods. I understand the challenge of summarizing 6 different models, but sometimes there is a place for including key equations.
2.) I would like to see physical variables from both the N-ICE observations and the models (those without prescribed physics). Even though the focus here is on BGC, the ice environment is critical for light and nutrient dynamics and thus for understanding sea-ice algal growth. Please consider adding another plot and adding to the Results and Discussion accordingly. Current places in the writing where the physics were alluded to but could use more backing were L129 and L143-144.
3.) It is near impossible to make sense of the nutrient validation when there is only one time point, which the authors themselves acknowledge (L169-172). Have the authors looked into other time series, such as those from Green Edge, CASES (Cape Bathurst), Resolute Bay, etc.?

The writing itself is generally good and clear. Here are a few line-by-line comments:
L8. Tromso is misspelled.
L37-38. Please consider adding a citation for the claim of significant effects throughout trophic levels.
L51. Please specify that this is maximum algal growth rate.
L67. I feel that for the last sentence of the introduction, this places a lot of emphasis on temporal variability, when your results are also about magnitude. Please consider revising.
L124. Is 83 to 83N correct? If so, please include more details about the drift trajectory.
L164-166. This sentence is relatively redundant for the information that it conveys. Perhaps trim to “Most models exhibited deviations in either phenology or bloom magnitude.”
L194-196. This sentence confused me. Something seems off with the “show to disagree” verb?
L220-221. This statement (“challenges encountering in simulating a refrozen lead”) seems important to understanding the models-observations comparison, but it was never discussed before the Conclusion. Please consider treating this in greater detail in the Discussion.
L230. This is a minor point, but please consider a more common word than “auspicabile”
Figure 1. Please report n for the observations and clarify whether replicates are from different ice cores or technical replicates from the same core.
Table 2. For SIESTA tuning strategy, what does “possibility to keep position” mean?

Citation: https://doi.org/10.5194/egusphere-2025-1107-RC1
- AC1:
  'Reply on RC1', Letizia Tedesco, 03 Jul 2025
  We thank Reviewer 1 for their thoughtful and constructive feedback on our manuscript. We are pleased that the reviewer found the intercomparison timely, well-structured, and valuable for advancing sea-ice biogeochemical modelling. We also appreciate the recognition of the effort involved in harmonising the forcing and analysis across six independent modelling teams.
  In response to the reviewer’s comments, we have planned several key revisions aimed at improving the clarity and impact of the manuscript, while staying within the scope of the Brief Communication format. These include:
  Adding brief descriptions of each model and relevant equations to the Supplementary Material;
  
  Clarifying the goals of the study, with emphasis on our primary aim: understanding differences among models and tuning strategies, rather than resolving new process-level insights;
  
  Expanding the discussion of tuning choices, with more detailed explanations of their rationale, model-specific constraints, and links to structural model differences;
  
  Improving the integration of physical drivers, and enhancing the interpretation of model–data mismatch using observed physical variables;
  
  Revising Table 2 to include more quantitative information on parameter adjustments and their effects.
  
  We believe these revisions will directly address the reviewer’s concerns and substantially enhance the manuscript’s clarity, accessibility, and overall scientific contribution. Please refer to the attached PDF for our detailed, point-by-point rebuttal.
  
  Citation: https://doi.org/10.5194/egusphere-2025-1107-AC1
RC2:
'Comment on egusphere-2025-1107', Anonymous Referee #2, 22 May 2025

# General comments
This study provides an intercomparison of six 1D sea-ice biogeochemical models with a focus on the assessment of simulating spring ice algae blooms and associated nutrient variability. The main findings are that: none of the models adequately captured blooms with their default parameters; tuning improved the ice algae blooms but not the nutrient variability; and more systematic tuning strategies are suggested as a next step. I think it is a great effort to conduct an intercomparison study for sea-ice BGC models, which has not been done except for Watanabe et al. (2019). The manuscript is generally easy to follow and clearly structured. However, it would benefit from more careful proofreading to address minor editorial issues and improve overall readability.
The manuscript type is “brief communication”, so I understand that it is written briefly. However, I find it a bit too brief considering the following three points. Therefore, I recommend major revisions and provide suggestions below.
## Physical data. The manuscript lacks the presentation of physical data, even though the text mentions the existence of such data (e.g., L21, L137, L143). Given that physical processes drive the circulation of biogeochemical variables, it seems essential to show the comparison of physical model and observational data, such as snow thickness, ice thickness, and sea surface temperature. With these additions, the study may be able to address (or at least speculate) whether the simulated differences and biases are due to the physical processes.
## Quantitative assessment. Table 2 can be improved by incorporating quantitative findings. Currently, it is a qualitative description that is not very informative and is a bit difficult to follow; one can easily guess the qualitative changes as described in Table 2 (e.g., lower biomass was increased by lowering silica limitation). What would be informative and advance the knowledge is to report the amount of improvements by the amount of parameter adjustments.
## Connection to previous studies. The results and discussion section as well as the conclusions section (L162 onwards) do not appear to contain any reference to previous studies. Hence, it is unclear how this study contributes to the field. This can be achieved by incorporating discussion of the results with previous studies. Specifically, I think that the discussion can be improved by incorporating tuning strategies and intercomparison studies conducted for ocean BGC modelling (e.g., Schartau et al., 2017). Some of these are already mentioned in the manuscript (e.g., L226-234), but it would be better to link these with relevant previous studies to provide a practical direction for future studies.
Schartau et al. (2017). Reviews and syntheses: parameter identification in marine planktonic ecosystem modelling. Biogeosciences.
# Specific comments
L21. “N-ICE2015” is too technical for the abstract. It is better to inform the region and season instead (e.g., north of Svalbard during April-June, 2015).
L22. “tuning” and “adjustments” are used together and they seem to mean the same thing, but this is unclear. I suggest replacing “without tuning, adjustments” by “using their default parameter sets, tuning”.
L23. It would be good to add a sentence here to explain why “adjustments improved biomass simulations but had a limited impact on nutrient representation”. (at least speculate even though the cause is unknown)
L24. It may be informative to add a few words to describe what “harmonised” means here.
L28. Should “ice algae” be “bottom ice” instead, given the following phrase “representing the largest biomass fraction in sea ice”?
L47. “IAMIP1” should be spelled out.
L53. “CMIP6” should be spelled out.
L67. I suggest replacing “existing” by “participating”, as the former sounds like these are all 1D models that exist.
L79. “little” or none? Horizontal advection terms are neglected.
L88. It would be helpful to briefly explain what “dynamic layering” means.
L92. “Chemical Functional Families (CFF)” does not sound familiar in marine BGC modelling. Please use an alternative term or provide a reference.
L124. Please correct the latitudinal range “83 to 83 N”.
L126. It is more intuitive to write the range in an increasing order “80.5 and 81.8 N”.
L139. “Duarte et al. 2017” is one of the participating models in this study? If so, why is the performance poor? Presumably, the model was previously tuned to this study site.
L143. I do not see these physical metrics compared (sea-ice season timing, ice thickness, and snow thickness).
L149. “the extent of biases” will depend on the location where tuning was conducted for the default parameter sets. Hence, it would be helpful to indicate for which region each model was tuned (in Table 1 and/or the text). This will also give an indication for the “portability” of the model (Sec 2.8 of Friedrichs et al. 2007).
Friedrichs et al. (2007). Assessment of skill and portability in regional marine biogeochemical models: Role of multiple planktonic groups, JGR-Oceans.
L158. Please describe the source of the atmospheric forcing used here.
L159. Please specify which model is the one without a thermodynamic component.
L180. “Change in the initial simulation date” seems strange to be considered a tuning parameter.

Citation: https://doi.org/10.5194/egusphere-2025-1107-RC2
- AC2:
  'Reply on RC2', Letizia Tedesco, 03 Jul 2025
  We thank Reviewer 2 for their constructive suggestions aimed at enhancing the scientific value and clarity of our study. We appreciate the reviewer’s recognition of the novelty of this intercomparison effort for sea-ice biogeochemical (BGC) models and their support for the overall approach.
  In response to the reviewer’s comments, we plan to implement the following key revisions:
  Inclusion of physical variables in a new figure, along with corresponding discussion;
  
  Enhanced explanation of model tuning strategies, with expanded detail in Table 2 on parameter changes and resulting impacts on biomass and nutrient simulations;
  
  Clear indication of each model’s original tuning region to provide context for default performance and portability;
  
  Expanded discussion that connects our findings to previous intercomparison and tuning studies in ocean BGC modelling, while highlighting the novelty of our work as the first such intercomparison focused on sea-ice BGC;
  
  We believe these changes improve the transparency, contextual depth, and scientific rigour of the manuscript, and we thank the reviewer again for helping us strengthen this contribution. Please refer to the attached PDF for our detailed, point-by-point rebuttal.
  
  Citation: https://doi.org/10.5194/egusphere-2025-1107-AC2

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2025-1107', Anonymous Referee #1, 12 May 2025

Review of Tedesco et al. “Brief communication: Intercomparison study reveals pathways for improving the representation of sea-ice biogeochemistry in models”

The manuscript presents an intercomparison between 6 one-dimensional sea-ice biogeochemical models. Models were forced with the same atmospheric and oceanic data from a time series of observations from a refrozen lead and validated with associated chlorophyll a, nitrate, and silicate data. Models were first run with their default parameterizations, and then teams were asked to tune their models to best match the observations. The authors found that with tuning, most models were able to reproduce chlorophyll a timing and concentration but not so much nutrients. Model teams also differed in their tuning choices.
I think the exercise of model intercomparison is valuable and this is a timely moment to do one for sea-ice BGC, as the number of models has been increasing. I also think the exercise is well-structured and shows significant effort on the part of many people in independently running and tuning the models with the same set of forcings (not a given in other model intercomparisons) in order to reveal a process understanding. As the manuscript is currently written, however, it is difficult for a reader outside of the group to gain much insight or understanding from the exercise. I know this is meant to be a “brief communication”, but I think it deserves a far more detailed paper, for which the changes would probably be considered major revisions.
1.) My main concern surrounds the brief treatment of A) describing what the models are doing and B) usefully synthesizing the outcomes. The manuscript sets up its goal as wanting to gain increased process understanding (rather than simply comparing model outputs, which is more the goal of intercomparisons like Watanabe et al. 2019 that they cite) but I did not feel like it went beyond listing individual model tuning in a way that informed my understanding of the sea-ice ecosystem.
What were key parameter values before/after tuning? Table 2/the list in L178-182 seems like it should be the heart of the Discussion but I didn’t know why modeling teams chose to make those tuning adjustments, whether any choices were specific to model design or previous parameterization, or how model outcomes might be tied to their design. E.g., Can anything be said about models that are BL vs. DE or quota vs. Redfield? Does increased model complexity improve match to observations? Were the tuning changes still within reasonable values for BGC processes, or do they suggest that model physics might be off? What would this work mean for future sea-ice researchers, especially those adjacent to the author group? Lastly, depending on the direction of Discussion, it may be useful to include more model description than currently exists in the Methods. I understand the challenge of summarizing 6 different models, but sometimes there is a place for including key equations.
2.) I would like to see physical variables from both the N-ICE observations and the models (those without prescribed physics). Even though the focus here is on BGC, the ice environment is critical for light and nutrient dynamics and thus for understanding sea-ice algal growth. Please consider adding another plot and adding to the Results and Discussion accordingly. Current places in the writing where the physics were alluded to but could use more backing were L129 and L143-144.
3.) It is near impossible to make sense of the nutrient validation when there is only one time point, which the authors themselves acknowledge (L169-172). Have the authors looked into other time series, such as those from Green Edge, CASES (Cape Bathurst), Resolute Bay, etc.?

The writing itself is generally good and clear. Here are a few line-by-line comments:
L8. Tromso is misspelled.
L37-38. Please consider adding a citation for the claim of significant effects throughout trophic levels.
L51. Please specify that this is maximum algal growth rate.
L67. I feel that for the last sentence of the introduction, this places a lot of emphasis on temporal variability, when your results are also about magnitude. Please consider revising.
L124. Is 83 to 83N correct? If so, please include more details about the drift trajectory.
L164-166. This sentence is relatively redundant for the information that it conveys. Perhaps trim to “Most models exhibited deviations in either phenology or bloom magnitude.”
L194-196. This sentence confused me. Something seems off with the “show to disagree” verb?
L220-221. This statement (“challenges encountering in simulating a refrozen lead”) seems important to understanding the models-observations comparison, but it was never discussed before the Conclusion. Please consider treating this in greater detail in the Discussion.
L230. This is a minor point, but please consider a more common word than “auspicabile”
Figure 1. Please report n for the observations and clarify whether replicates are from different ice cores or technical replicates from the same core.
Table 2. For SIESTA tuning strategy, what does “possibility to keep position” mean?

Citation: https://doi.org/10.5194/egusphere-2025-1107-RC1
- AC1:
  'Reply on RC1', Letizia Tedesco, 03 Jul 2025
  We thank Reviewer 1 for their thoughtful and constructive feedback on our manuscript. We are pleased that the reviewer found the intercomparison timely, well-structured, and valuable for advancing sea-ice biogeochemical modelling. We also appreciate the recognition of the effort involved in harmonising the forcing and analysis across six independent modelling teams.
  In response to the reviewer’s comments, we have planned several key revisions aimed at improving the clarity and impact of the manuscript, while staying within the scope of the Brief Communication format. These include:
  Adding brief descriptions of each model and relevant equations to the Supplementary Material;
  
  Clarifying the goals of the study, with emphasis on our primary aim: understanding differences among models and tuning strategies, rather than resolving new process-level insights;
  
  Expanding the discussion of tuning choices, with more detailed explanations of their rationale, model-specific constraints, and links to structural model differences;
  
  Improving the integration of physical drivers, and enhancing the interpretation of model–data mismatch using observed physical variables;
  
  Revising Table 2 to include more quantitative information on parameter adjustments and their effects.
  
  We believe these revisions will directly address the reviewer’s concerns and substantially enhance the manuscript’s clarity, accessibility, and overall scientific contribution. Please refer to the attached PDF for our detailed, point-by-point rebuttal.
  
  Citation: https://doi.org/10.5194/egusphere-2025-1107-AC1
RC2:
'Comment on egusphere-2025-1107', Anonymous Referee #2, 22 May 2025

# General comments
This study provides an intercomparison of six 1D sea-ice biogeochemical models with a focus on the assessment of simulating spring ice algae blooms and associated nutrient variability. The main findings are that: none of the models adequately captured blooms with their default parameters; tuning improved the ice algae blooms but not the nutrient variability; and more systematic tuning strategies are suggested as a next step. I think it is a great effort to conduct an intercomparison study for sea-ice BGC models, which has not been done except for Watanabe et al. (2019). The manuscript is generally easy to follow and clearly structured. However, it would benefit from more careful proofreading to address minor editorial issues and improve overall readability.
The manuscript type is “brief communication”, so I understand that it is written briefly. However, I find it a bit too brief considering the following three points. Therefore, I recommend major revisions and provide suggestions below.
## Physical data. The manuscript lacks the presentation of physical data, even though the text mentions the existence of such data (e.g., L21, L137, L143). Given that physical processes drive the circulation of biogeochemical variables, it seems essential to show the comparison of physical model and observational data, such as snow thickness, ice thickness, and sea surface temperature. With these additions, the study may be able to address (or at least speculate) whether the simulated differences and biases are due to the physical processes.
## Quantitative assessment. Table 2 can be improved by incorporating quantitative findings. Currently, it is a qualitative description that is not very informative and is a bit difficult to follow; one can easily guess the qualitative changes as described in Table 2 (e.g., lower biomass was increased by lowering silica limitation). What would be informative and advance the knowledge is to report the amount of improvements by the amount of parameter adjustments.
## Connection to previous studies. The results and discussion section as well as the conclusions section (L162 onwards) do not appear to contain any reference to previous studies. Hence, it is unclear how this study contributes to the field. This can be achieved by incorporating discussion of the results with previous studies. Specifically, I think that the discussion can be improved by incorporating tuning strategies and intercomparison studies conducted for ocean BGC modelling (e.g., Schartau et al., 2017). Some of these are already mentioned in the manuscript (e.g., L226-234), but it would be better to link these with relevant previous studies to provide a practical direction for future studies.
Schartau et al. (2017). Reviews and syntheses: parameter identification in marine planktonic ecosystem modelling. Biogeosciences.
# Specific comments
L21. “N-ICE2015” is too technical for the abstract. It is better to inform the region and season instead (e.g., north of Svalbard during April-June, 2015).
L22. “tuning” and “adjustments” are used together and they seem to mean the same thing, but this is unclear. I suggest replacing “without tuning, adjustments” by “using their default parameter sets, tuning”.
L23. It would be good to add a sentence here to explain why “adjustments improved biomass simulations but had a limited impact on nutrient representation”. (at least speculate even though the cause is unknown)
L24. It may be informative to add a few words to describe what “harmonised” means here.
L28. Should “ice algae” be “bottom ice” instead, given the following phrase “representing the largest biomass fraction in sea ice”?
L47. “IAMIP1” should be spelled out.
L53. “CMIP6” should be spelled out.
L67. I suggest replacing “existing” by “participating”, as the former sounds like these are all 1D models that exist.
L79. “little” or none? Horizontal advection terms are neglected.
L88. It would be helpful to briefly explain what “dynamic layering” means.
L92. “Chemical Functional Families (CFF)” does not sound familiar in marine BGC modelling. Please use an alternative term or provide a reference.
L124. Please correct the latitudinal range “83 to 83 N”.
L126. It is more intuitive to write the range in an increasing order “80.5 and 81.8 N”.
L139. “Duarte et al. 2017” is one of the participating models in this study? If so, why is the performance poor? Presumably, the model was previously tuned to this study site.
L143. I do not see these physical metrics compared (sea-ice season timing, ice thickness, and snow thickness).
L149. “the extent of biases” will depend on the location where tuning was conducted for the default parameter sets. Hence, it would be helpful to indicate for which region each model was tuned (in Table 1 and/or the text). This will also give an indication for the “portability” of the model (Sec 2.8 of Friedrichs et al. 2007).
Friedrichs et al. (2007). Assessment of skill and portability in regional marine biogeochemical models: Role of multiple planktonic groups, JGR-Oceans.
L158. Please describe the source of the atmospheric forcing used here.
L159. Please specify which model is the one without a thermodynamic component.
L180. “Change in the initial simulation date” seems strange to be considered a tuning parameter.

Citation: https://doi.org/10.5194/egusphere-2025-1107-RC2
- AC2:
  'Reply on RC2', Letizia Tedesco, 03 Jul 2025
  We thank Reviewer 2 for their constructive suggestions aimed at enhancing the scientific value and clarity of our study. We appreciate the reviewer’s recognition of the novelty of this intercomparison effort for sea-ice biogeochemical (BGC) models and their support for the overall approach.
  In response to the reviewer’s comments, we plan to implement the following key revisions:
  Inclusion of physical variables in a new figure, along with corresponding discussion;
  
  Enhanced explanation of model tuning strategies, with expanded detail in Table 2 on parameter changes and resulting impacts on biomass and nutrient simulations;
  
  Clear indication of each model’s original tuning region to provide context for default performance and portability;
  
  Expanded discussion that connects our findings to previous intercomparison and tuning studies in ocean BGC modelling, while highlighting the novelty of our work as the first such intercomparison focused on sea-ice BGC;
  
  We believe these changes improve the transparency, contextual depth, and scientific rigour of the manuscript, and we thank the reviewer again for helping us strengthen this contribution. Please refer to the attached PDF for our detailed, point-by-point rebuttal.
  
  Citation: https://doi.org/10.5194/egusphere-2025-1107-AC2

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload

ED: Reconsider after major revisions (further review by editor and referees) (10 Jul 2025) by K. M. Meiners

This study presents an intercomparison and tuning exercise of six 1-D sea-ice biogeochemical models presented in a TC Brief Communication format. While the reviewers consider such an intercomparison a worthwhile and timely effort, both reviewers raise questions and comments that require substantial/major revisions of the manuscript. A main concern of both reviewers is that that manuscript lacks detail in regards to model descriptions, physical data and key learnings from the study. Thus, the authors should consider carefully if the requested amendments can be fit into a Brief Communication format, or if the amended manuscript should be re-submitted as a full article. While I understand the wish of the authors to stick with the Brief Communication format this might not be the most suitable format for this study.
A number of major comments were made by the reviewers, all taken up for consideration in the final author’s responses describing their strategy for amending the manuscript for re-submission.

The following provides a summary of reviewer comments that will require specific attention:
1) An improved (more detailed) description of the different models and a (quantitative) synthesis, and detailed discussion of the findings/learnings from the tuning exercise is needed. How do the tuning efforts relate to the respective model designs, and initial choices of parameterisation? Did the tuning exercise show/help identify systematic changes in different model groups (e.g., BL versus DE, quota versus Redfield set-ups)?
2) An improved and more detailed description of the physical environment (including the observational and modelled data) is needed. How well did the modelled physical variables match the observations and how did this influence the (BGC-focussed) results presented in this study?
3) Reviewer2 highlights the need to incorporate a discussion on previous tuning and intercomparison studies conducted for ocean BGC modelling, and how they relate to the strategy applied in this intercomparison exercise.
4) Reviewer 1 highlights the limitation in the N-ICE observations regarding nutrient data and mentions potential other data sets. Can the authors boost their arguments for using the N-ICE observations (only)?

Please consider these carefully and I am looking forward to a revised version of this manuscript.

Hide

AR by Letizia Tedesco on behalf of the Authors (01 Nov 2025) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (09 Nov 2025) by K. M. Meiners

RR by Anonymous Referee #2 (18 Nov 2025)

RR by Anonymous Referee #1 (19 Nov 2025)

Suggestions for revision or reasons for rejection

Rereview of Tedesco et al. “Brief communication: Intercomparison study reveals pathways for improving the representation of sea-ice biogeochemistry in models”

I thank the authors for the time and effort spent revising the paper. I do think the paper is clearer in its intent and making its results more transparent and therefore useful to readers. For example, adding the model summaries to the supplement, while perhaps tedious, is much better than sorting through 6 citations and will hopefully encourage more model use and collaboration in the future. I appreciated the expanded discussion of the tuning choices made and how they related to the initial model development or the young ice observational context.

I recommend its publication after addressing a few more minor comments below. Line numbers refer to the non-tracked changes version.

L109-114. I am not sure the addition of information in parentheses to this paragraph was helpful. It feels a bit redundant with the following paragraph.

L169-173. Please consider adding the time resolution/intervals of the forcing data to help with interpretation of the models’ time series.

Also L170. Is this 2 m air temperature? How is this forcing different from the simulated surface temperature mentioned in the results and shown in Fig. 1? I may be misunderstanding, but either surface temperature is snow temperature, or all the models should be forced with and therefore perfectly matching air temperature?

L183. “minor” variability seems questionable here. Although I agree that the new ice is quite thin, a doubling from ~0.2 m observations to 0.4 m in simulations might be notable; the melt is also quite dramatic in one of the models. Please consider describing a bit more precisely.

L262. I might rephrase “for some models even after tuning” or start a new sentence.

L271-272. I think this sentence a key point, as it situates this study in terms of the chosen observational dataset AND the future Arctic. Perhaps consider adding it to the abstract in some form, if word count allows.

Table 2 has been greatly improved with more quantitative and specific information. Please consider adding the observational max and timing of peak [Chla] in the table legend so that readers don’t have to refer back to Fig 2. Also, whether here or in the supplement, please consider reporting the key tuning parameters for all models—for example, what is the initial seawater [Chla] for the non-BFM models?

Hide

ED: Publish subject to minor revisions (review by editor) (05 Dec 2025) by K. M. Meiners

AR by Letizia Tedesco on behalf of the Authors (09 Dec 2025) Author's response Author's tracked changes Manuscript

ED: Publish subject to technical corrections (22 Dec 2025) by K. M. Meiners

AR by Letizia Tedesco on behalf of the Authors (25 Dec 2025) Manuscript

Journal article(s) based on this preprint

28 Jan 2026

Brief communication: Intercomparison study reveals pathways for improving the representation of sea-ice biogeochemistry in models

Letizia Tedesco, Giulia Castellani, Pedro Duarte, Meibing Jin, Sebastien Moreau, Eric Mortenson, Benjamin Tobey Saenz, Nadja Steiner, and Martin Vancoppenolle

The Cryosphere, 20, 723–736, https://doi.org/10.5194/tc-20-723-2026,https://doi.org/10.5194/tc-20-723-2026, 2026

Short summary

Letizia Tedesco, Giulia Castellani, Pedro Duarte, Meibing Jin, Sebastien Moreau, Eric Mortenson, Benjamin Tobey Saenz, Nadja Steiner, and Martin Vancoppenolle

Viewed

Total article views: 2,617 (including HTML, PDF, and XML)

HTML	PDF	XML	Total	BibTeX	EndNote
2,457	120	40	2,617	88	94

HTML: 2,457
PDF: 120
XML: 40
Total: 2,617
BibTeX: 88
EndNote: 94

Views and downloads (calculated since 15 Apr 2025)

Month	HTML	PDF	XML	Total
Apr 2025	103	17	2	122
May 2025	66	7	4	77
Jun 2025	39	10	5	54
Jul 2025	40	12	6	58
Aug 2025	441	2	0	443
Sep 2025	1,621	5	1	1,627
Oct 2025	69	5	1	75
Nov 2025	31	15	5	51
Dec 2025	29	23	9	61
Jan 2026	18	24	7	49

Cumulative views and downloads (calculated since 15 Apr 2025)

Month	HTML	PDF	XML	Total
Apr 2025	103	17	2	122
May 2025	66	7	4	77
Jun 2025	39	10	5	54
Jul 2025	40	12	6	58
Aug 2025	441	2	0	443
Sep 2025	1,621	5	1	1,627
Oct 2025	69	5	1	75
Nov 2025	31	15	5	51
Dec 2025	29	23	9	61
Jan 2026	18	24	7	49

Viewed (geographical distribution)

Total article views: 2,477 (including HTML, PDF, and XML) Thereof 2,477 with geography defined and 0 with unknown origin.

Country	#	Views	%

Latest update: 28 Jan 2026

Download

The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Preprint (935 KB)
Metadata XML

Short summary

Sea ice is home to tiny algae that support polar marine life, but understanding how they grow and interact with their environment remains challenging. We compared six computer models that simulate these algae and nutrients in sea ice, testing them against real-world data from Arctic sea ice. Our results show that while models can capture algal growth, they struggle to represent nutrient changes. Improving these models will help in understanding how climate change affects polar marine ecosystems.


Total:	0
HTML:	0
PDF:	0
XML:	0