Site-level model intercomparison of high latitude and high altitude soil thermal dynamics in tundra and barren landscapes

Ekici, A.; Chadburn, S.; Chaudhary, N.; Hajdu, L. H.; Marmy, A.; Peng, S.; Boike, J.; Burke, E.; Friend, A. D.; Hauck, C.; Krinner, G.; Langer, M.; Miller, P. A.; Beer, C.

doi:https://doi.org/10.5194/tc-9-1343-2015

Articles | Volume 9, issue 4

https://doi.org/10.5194/tc-9-1343-2015

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

https://doi.org/10.5194/tc-9-1343-2015

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

Articles | Volume 9, issue 4

Research article

|

22 Jul 2015

Research article |

| 22 Jul 2015

Site-level model intercomparison of high latitude and high altitude soil thermal dynamics in tundra and barren landscapes

A. Ekici, S. Chadburn, N. Chaudhary, L. H. Hajdu, A. Marmy, S. Peng, J. Boike, E. Burke, A. D. Friend, C. Hauck, G. Krinner, M. Langer, P. A. Miller, and C. Beer

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Final revised paper (published on 22 Jul 2015)
Supplement to the final revised paper
Preprint (discussion started on 18 Sep 2014)

Interactive discussion

Status: closed

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

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- Supplement

RC C2197: 'Review', Anonymous Referee #1, 31 Oct 2014
- AC C3075: 'response to referee#1', Altug Ekici, 09 Feb 2015
RC C2808: 'Comments', Anonymous Referee #2, 09 Jan 2015
- AC C3076: 'response to referee#2', Altug Ekici, 09 Feb 2015

Peer-review completion

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

AR by Altug Ekici on behalf of the Authors (09 Feb 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (02 Mar 2015) by Tingjun Zhang (deceased)

RR by Anonymous Referee #2 (10 Mar 2015)

RR by Anonymous Referee #1 (30 Mar 2015)

Suggestions for revision or reasons for rejection

The revision has certainly enhanced the paper. First, I want to give some sentences on the authors’ comments:

Comment 5 about structure: The authors keep their structure, this is ok, but still this results in redundancies and other issues. In the end, it is up to the authors to evaluate this.

Comment 7: What I wanted to say is that you can delete the ALT comparison to equilibrium models. You are not using a (semi)-empirical approach, so it makes no sense to compare your transient modelling with this. We are all aware of the advantages of transient modelling in terms of modelling ALT more precisely. My point is that the two schemes are virtually not comparable, and therefore it is not necessary in your paper.

Comment 9: We know what “spin-up” is. But your explanation is interesting. Of course you need longer spin-up if the model soil layers is deeper. However, there is absolutely no correlation between spin-up time and depth of model domain. E.g. Orchidee has 43 m domain and 10000 years spin up. “Overkill”? You have 500 years for LPJ (2 m domain) and 10 year COUP (10 m domain), for the same domain you have 50 years for JSBACH. So, no relation. Maybe there are other reason, then you should give them.

Still a major comment is the following: I cannot see any comment on the last paragraph of my first review:

“(…) One improvement could be to evaluate really the effect of the different uncertainties, so what is the isolated effect of the snow scheme for the ground temperatures, similar to the effect of the soil scheme. Which of these effects should be improved, maybe a complicated soil scheme is not that important than a more sophisticated snow scheme. Maybe in different climate settings the relative effect is different. I could imagine that a good soil scheme is more important in sedimentary tundra environments than in barren ground and rock? Maybe the snow representation can be more simple in environment A than B? Such questions would certainly increase the merit of this study as they would give useful recommendations. “

My point is that you in in general do not evaluate systematically the performance of the models, and this is related how you designed the study.

You are testing three elements:
1. How is the snow build-up and melt modelled?
2. How is the thermal effect of snow modelled?
3. How is the soil thermal regime modelled?

As far as I can see in your study design, you force the model mostly with the same observations/data for each site. This is fine. Then you run the model and look on the performance. Of course, there will be deviations, starting with that the models in a varying degree manage to re-produce snow cover. This is the first deviation. Then you model the snow (thermal) processes, fine, and here deviations can be attributed to the snow model formulation and of course how snow development is modelled. To isolated look on the performance of the snow scheme, the model should be forced with the snow observations, at least with the same series. The same applies for the sub-soil scheme, the deviations you show are caused by how good the snow is modelled, not how the soil model scheme is formulated. To evaluate the latter, you should force the model with the same ground surface temperature series (under the snow or without snow), for instance. Then deviations are due to the model formulation. Maybe, this is impossible to achieve with you models, I do not know. But then you should comment on that at least.

So, in my opinion, your paper is certainly hard work, to a certain degree also valuable for the community, especially those developing and applying ESM to permafrost etc.

Other comments:

p 13, l 10: Schilthorn site. This is a steep mountain site, so there are certainly various 3D effects influencing the ground temperature profile. Should be mentioned at least.
p. 14, l 1..: I think for decadal effects, you need certainly more than 30 m.
p. 15, l 31: See above, delete the whole paragraph, I do not understand the point.
p. 16, l. 30: In your study your virtually do not show point 7, so delete.

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ED: Reconsider after major revisions (04 Apr 2015) by Tingjun Zhang (deceased)

AR by Altug Ekici on behalf of the Authors (16 May 2015) Author's response Manuscript

ED: Publish subject to minor revisions (Editor review) (18 Jun 2015) by Tingjun Zhang (deceased)

AR by Altug Ekici on behalf of the Authors (19 Jun 2015) Author's response Manuscript

ED: Publish as is (02 Jul 2015) by Tingjun Zhang (deceased)

AR by Altug Ekici on behalf of the Authors (03 Jul 2015)

Short summary

This paper compares the performance of different land models in estimating soil thermal regimes at distinct cold region landscape types. Comparing models with different processes reveal the importance of surface insulation (snow/moss layer) and soil internal processes (heat/water transfer). The importance of model processes also depend on site conditions such as high/low snow cover, dry/wet soil types.