Evaluation of different methods to model near-surface turbulent fluxes for a mountain glacier in the Cariboo Mountains, BC, Canada

Radić, Valentina; Menounos, Brian; Shea, Joseph; Fitzpatrick, Noel; Tessema, Mekdes A.; Déry, Stephen J.

doi:https://doi.org/10.5194/tc-11-2897-2017

Articles | Volume 11, issue 6

https://doi.org/10.5194/tc-11-2897-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/tc-11-2897-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 11, issue 6

Research article

|

12 Dec 2017

Research article |

| 12 Dec 2017

Evaluation of different methods to model near-surface turbulent fluxes for a mountain glacier in the Cariboo Mountains, BC, Canada

Valentina Radić, Brian Menounos, Joseph Shea, Noel Fitzpatrick, Mekdes A. Tessema, and Stephen J. Déry

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Final revised paper (published on 12 Dec 2017)
Preprint (discussion started on 31 May 2017)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Referee review of manuscript tc-2017-80', Jonathan Conway, 12 Jul 2017
- AC1: 'Response to Referee #1', Valentina Radic, 17 Sep 2017
RC2: 'Important paper on turbulent fluxes over glaciers', Ruzica Dadic, 07 Aug 2017
- AC2: 'Response to Referee #2', Valentina Radic, 17 Sep 2017

Peer-review completion

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

AR by Valentina Radic on behalf of the Authors (24 Sep 2017) Manuscript

ED: Referee Nomination & Report Request started (05 Oct 2017) by Thomas Mölg

RR by Jonathan Conway (20 Oct 2017)

Suggestions for revision or reasons for rejection

General Comments
The authors have thoroughly addressed the comments raised in my initial review and present a much-improved manuscript. The new and revised analyses make the results much more compelling and present a clear message. In particular, the calculation of Kmax using on-off glacier temperature difference is an addition aspect of novelty and a significant contribution. The inability of measurement errors to account for the observed differences between the model and measurements adds additional urgency to the need for further work to derive better functions to compute turbulent heat fluxes over glaciers. The combination of the two best performing methods for friction velocity and the heat fluxes provides a new avenue for further investigation. I have some remaining minor comments, but no overall general concerns. The manuscript presents a well-constructed and valuable contribution to our understanding of turbulent heat fluxes over glacier surfaces.

Specific Comments (page-line):
24:2-6 The log-log correlation between ‘observed’ k and the on-off glacier temperature difference is not very strong (r = -0.34) and the figure presented (second two panels of Figure 10) doesn’t support the statement that “as the temperature difference increases, indicative of higher static stability, the k parameter decreases”. From the figure it seems as if high values of k don’t appear under large temperature differences, but certainly there is no obvious power-law relationship presented. A log-log plot may highlight this feature. This result is not central to the main result, so I would suggest revising the text or removing this analysis.
25:9 It is a little ambiguous in the text what formulae were used to calculate heat fluxes for the hybrid method. From what I can tell, equations 19-20, 22-23 were used to calculate QH and QE, but that instead of calculating u* with equation 16 and 21, u* is calculated with equations 33 and 36. Is this correct? If so, then perhaps the full list of equations can be given. The text at 25:12 should also refer to “exchange coefficients for heat” rather than ‘heat fluxes”. Also, please describe how Kint was calculated for the hybrid method (presumably from equation 38?) as well as the value for Pr used.

Editorial Comments
23:2 Please change the use of parenthesis to denote opposites into a full sentence. E.g. “…explains 61 % of the variance in the 2012 observations and 19 % of variance in 2010 observations.”
25:14 Please add reference to Table 2 with Figure 8.
It is sometimes difficult to understand which panel of a figure is being referred to in the text and to match the figure captions describing each panel. It would be useful if the multi-panel figure panels were labelled (a), (b), (c)... etc. to aid the reader.

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ED: Publish subject to minor revisions (review by editor) (20 Oct 2017) by Thomas Mölg

AR by Valentina Radic on behalf of the Authors (21 Oct 2017) Author's response Manuscript

ED: Publish as is (30 Oct 2017) by Thomas Mölg

AR by Valentina Radic on behalf of the Authors (07 Nov 2017) Manuscript

Short summary

Our overall goal is to improve the numerical modeling of glacier melt in order to better predict the future of glaciers in Western Canada and worldwide. Most commonly used models rely on simplifications of processes that dictate melting at a glacier surface, in particular turbulent processes of heat exchange. We compared modeled against directly measured turbulent heat fluxes at a valley glacier in British Columbia, Canada, and found that more improvements are needed in all the tested models.