A new sub-grid surface mass balance and flux model for continental-scale ice sheet modelling: testing and last glacial cycle

Le Morzadec, K.; Tarasov, L.; Morlighem, M.; Seroussi, H.

doi:https://doi.org/10.5194/gmd-8-3199-2015

Articles | Volume 8, issue 10

https://doi.org/10.5194/gmd-8-3199-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/gmd-8-3199-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 8, issue 10

Development and technical paper

|

08 Oct 2015

Development and technical paper |

| 08 Oct 2015

A new sub-grid surface mass balance and flux model for continental-scale ice sheet modelling: testing and last glacial cycle

K. Le Morzadec, L. Tarasov, M. Morlighem, and H. Seroussi

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Final revised paper (published on 08 Oct 2015)
Supplement to the final revised paper
Preprint (discussion started on 01 Apr 2015)
Supplement to the preprint

Interactive discussion

Status: closed

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

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- Supplement

RC C688: 'Review of Le Morzadec et al 2015', Fuyuki SAITO, 08 May 2015
- RC C713: 'Review including correction of the previous one', Fuyuki SAITO, 12 May 2015
  - SC C884: 'Response to Fuyuki Saito review, kevin Le Morzadec, 24 May 2015', kevin le Morzadec, 27 May 2015
  - AC C954: 'Reply to referee with schematic figure explaining coupling', Lev Tarasov, 03 Jun 2015
  - AC C1535: 'Full response to review by Fuyuki Saito', Lev Tarasov, 28 Jul 2015
SC C948: 'Executive Editor Comment on "A new sub-grid surface mass balance and flux model for continental-scale ice sheet modelling: validation and last glacial cycle"', Astrid Kerkweg, 03 Jun 2015
- AC C955: 'code availability: response to executive editor comments', Lev Tarasov, 03 Jun 2015
RC C1081: 'Review of Le Morzadec et al.', Anonymous Referee #2, 13 Jun 2015
- AC C1534: 'Response to reviewer #2 comments', Lev Tarasov, 28 Jul 2015

Peer-review completion

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

AR by Lev Tarasov on behalf of the Authors (28 Jul 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (17 Aug 2015) by Didier Roche

RR by Anonymous Referee #2 (04 Sep 2015)

RR by Fuyuki Saito (09 Sep 2015)

Suggestions for revision or reasons for rejection

The revised manuscript are really improved than the previous one.
There are still, however, minor issues to be revised in order to
better clarify the work.

Abstract: define `CG'.

Sect. 2.1.1: In principle, at the extreme end, it is still possible to
have empty bins using the procedure of this paper. How to avoid them?
Or the DEM in this paper just does not have such distribution at all?

p6: W should be W_k in order to explicitly denote the bin
dependencies at least at the first appearance.

Eq. 3: Sorry, I did not realize this point in the review of GMDD.
Usually the left hand side is the time derivative of `thickness',
not surface elevation, because of the time derivative of the
bedrock elevation.
It seems, from the Eq. (5), the bedrock evolution is neglected
(i.e., h^t_{b,k} is cancelled in the left hand side). This should
be better explained.
Relating to this, how the bedrock elevation is treated in SG
model? Kept constant through the time, or kept constant during
one-time step but update step by step (i.e., h^t_{b,k} \neq
h^{t+1}_{b,k} but assume no evolution in Eq. 3), or other ways?
If the first, then h^t_{b,k} should be written as h_{b,k} because
it does not depends on time.

3.1.1 The maximum basal elevation seems to be 800m in Fig.S1, not
750 as in the text.

Figure 1:
As far as I understand, information of some grid cells are not
used in the computation of the effective width:
left-top 5, left-bottom 8, right-bottom 5 of the left block;
left-bottom 9, right-top 5, right-bottom 8 of the upper-right block;
left-top 8, left-bottom 8, right-bottom 6 of the lower-right block.
These are all diagonal grid cells of some of the target 7th
hypsometric cells. These should be removed from the figure.

Figure 2:
lower second figure: a little bit difficult to distinguish green
and blue.
Since SG is based on `bins', how about to replace the line graph
by `bar graphs'?

Figure 7: Need description of Para 1 and Para 2 (Eqs. 6 and 7,
respectively).

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ED: Publish subject to minor revisions (Editor review) (11 Sep 2015) by Didier Roche

AR by Lev Tarasov on behalf of the Authors (16 Sep 2015) Author's response Manuscript

ED: Publish as is (22 Sep 2015) by Didier Roche

AR by Lev Tarasov on behalf of the Authors (24 Sep 2015)

Short summary

A long-term challenge for any model of complex large-scale processes is accounting for the impact of unresolved sub-grid (SG) processes. We quantify the impact of SG mass-balance and ice fluxes on glacial cycle ensemble results for North America. We find no easy solutions to accurately capture these impacts. We show that SG process representation and associated parametric uncertainties can have significant impact on coarse resolution model results for glacial cycle ice sheet evolution.