The Utrecht Finite Volume Ice-Sheet Model: UFEMISM (version 1.0)

Berends, Constantijn J.; Goelzer, Heiko; van de Wal, Roderik S. W.

doi:https://doi.org/10.5194/gmd-14-2443-2021

Articles | Volume 14, issue 5

https://doi.org/10.5194/gmd-14-2443-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/gmd-14-2443-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 14, issue 5

Model description paper

|

05 May 2021

Model description paper |

| 05 May 2021

The Utrecht Finite Volume Ice-Sheet Model: UFEMISM (version 1.0)

Constantijn J. Berends, Heiko Goelzer, and Roderik S. W. van de Wal

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Final revised paper (published on 05 May 2021)
Preprint (discussion started on 08 Sep 2020)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review', Josefin Ahlkrona, 14 Oct 2020
RC2: 'Review of Berends et al., "The Utrecht Finite Volume Ice-Sheet Model: UFEMISM (version 1.0)"', Ralf Greve, 23 Dec 2020
AC1: 'Authors response', Tijn Berends, 18 Feb 2021

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Tijn Berends on behalf of the Authors (18 Feb 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (18 Feb 2021) by Alexander Robel

RR by Ralf Greve (09 Mar 2021)

Suggestions for revision or reasons for rejection

In general, the authors have done a good job revising the manuscript. In particular, I appreciate the inclusion of an attempt　to verify the SSA part of the model, and the performance of the model with respect to grounding line dynamics.

On the abbreviation "UFEMISM":
I still don't like it. Every knowledgeable reader will immediately assume that it is a finite-element model, and this is unnecessarily misleading. Granted, "UFVMISM" is not so nice to pronounce, but still, this is not good... Should be reconsidered.

P. 5, Eqs. (1), (2), and explaining text:
The quantity D shouldn't be called a "diffusivity" as it does not appear in any diffusion equation. What is usually called diffusivity D in this context is the depth integral of your D (e.g., Huybrechts et al. 1996, Greve and Blatter 2009 ["Dynamics of Ice Sheets and Glaciers", Springer]). This is the quantity that appears as a diffusivity in the SIA version of the ice thickness equation. However, it is irrelevant in your context as you don't have pure SIA dynamics, so that you must solve the general form of the ice thickness equation (your Eq. (B1)).

P. 5, Eqs. (1):
The variable zeta should be defined (appears only later in Eq. (D1)). As the non-transformed integral goes from b to z [e.g., Eq. (5.93) by Greve and Blatter (2009) without the contribution from Weertman sliding that you don't have], the transformed integral must go from zeta to 1, and the integration variable should be called zeta' or zeta-bar rather than zeta.

P. 6, l. 5-8:
Related to the above said, classifying your model as a Type I model in the sense of Huybrechts et al. (1996) is not appropriate. It does not fit this classification pattern at all as you do not solve the diffusive SIA version of the ice thickness equation.

P. 6, Eqs. (6),　(7), and explaining text:
As for the strain heating, it is not sufficient to say that this is "for grounded ice only". The form you give in Eq. (7) is only valid for the SIA. Since you have hybrid SIA/SSA dynamics for grounded ice rather than SIA, it is an additional simplification to assume that the strain heating is SIA-type. This should be stated clearly.

P. 15, l. 3-9:
I understand that the experiment, in the authors' words, "is not intended to present a realistic depiction of possible future Antarctic retreat. It only serves to demonstrate computational performance of the model." Nevertheless, I think it should be described in more detail to allow the readers assessing what is going on. Quoting my original review: "What are the initial conditions for the experiments? What are the physical parameters (rate factor, basal sliding law, heat conductivity & capacity, geothermal heat flux, etc.)? What is assumed for ice-shelf basal melting?" If the authors don't want to have this in the main text, it may be put in an appendix section.

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RR by Josefin Ahlkrona (09 Mar 2021)

ED: Publish subject to minor revisions (review by editor) (09 Mar 2021) by Alexander Robel

AR by Tijn Berends on behalf of the Authors (15 Mar 2021) Author's response

ED: Publish as is (29 Mar 2021) by Alexander Robel

AR by Tijn Berends on behalf of the Authors (30 Mar 2021)

Short summary

The largest uncertainty in projections of sea-level rise comes from ice-sheet retreat. To better understand how these ice sheets respond to the changing climate, ice-sheet models are used, which must be able to reproduce both their present and past evolution. We have created a model that is fast enough to simulate an ice sheet at a high resolution over the course of an entire 120 000-year glacial cycle. This allows us to study processes that cannot be captured by lower-resolution models.