the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Surface heat fluxes at coarse-blocky Murtèl rock glacier (Engadine, eastern Swiss Alps)
Abstract. We estimate the surface energy balance (SEB) of the Murtèl rock glacier, a seasonally snow-covered permafrost landform with a ventilated coarse-blocky active layer (AL) located in the eastern Swiss Alps. We focus on the parametrisation of the turbulent heat fluxes. Seasonally contrasting atmospheric conditions occur in the Murtèl cirque, with down-slope katabatic jets in winter and a strongly unstable atmosphere over the heated blocky surface in summer. We use a novel comprehensive sensor array both above ground surface and in the coarse-blocky AL to track the rapid coupling by convective heat and moisture fluxes between the atmosphere, the snow cover and the AL for the time period September 2020–September 2022. The in situ sensor array includes a sonic anemometer for eddy-covariance flux above ground and sub-surface long-wave radiation measurements in a natural cavity between the AL blocks. During the thaw seasons, the measurements suggest an efficient (ca. 90 %) export of the available net radiation by sensible and latent turbulent fluxes, thereby strongly limiting the heat available for melting ground ice. Turbulent export of heat and moisture drawn from the porous/permeable AL contributes to the well-known insulating effect of the coarse-blocky AL and partly explains the climate resiliency of rock glaciers. This self-cooling capacity is counteracted by an early snow melt-out date, exposing the low-albedo blocky surface to the intense June–July insolation, and reduced evaporative cooling due to exacerbated moisture scarcity in the near-surface AL during dry spells. With climate change, earlier snow melting and increased frequency, duration and intensity of heat waves and droughts are projected. Regarding the parametrisation of the turbulent fluxes, we successfully estimated the year-round turbulent fluxes using a modified Louis 1979 scheme despite seasonally contrasting atmospheric conditions and closed the monthly SEB within 20 W m−2, except during the snow melt-out months. Detected sensible turbulent fluxes from nocturnal ventilation processes, although a potentially important ground cooling mechanism, are within our 20 W m−2 uncertainty, because nighttime wind speeds are low. Wintertime katabatic wind speeds had to be scaled to close the SEB, which hints at the limits of parametrisations based on the Monin–Obukhov theory in complex mountain terrain and katabatic drainage flows. The present work contributes to the process understanding of the SEB and climate sensitivity of coarse-blocky landforms.
-
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
(15506 KB)
-
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(15506 KB) - Metadata XML
- BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-2109', Anonymous Referee #1, 29 Oct 2023
Review Surface heat fluxes at coarse-blocky Murtel rock glacier (Engadine, eastern Swiss Alps) - Amschwand et al.
The authors attempt to describe the surface energy balance in the active layer of a rock glacier in the Swiss Alps with an impressively well thought out measurement setup within a cavity complemented by a well established monitoring setup of the atmosphere above. Over two years they show how the energy input is nearly completely turned over, explaining the resilience rock glaciers have versus potential drivers of mass wasting but also providing an understanding what parameters are crucial to keep in mind in future, to anticipate the potential decay of ground ice in such landforms under a changing climate. They are also able to test a variety of stability corrections and discuss their suitability to estimate turbulent fluxes efficiently and show suitable fits for already established models for a rock glacier case.
The study is extremely well thought out, relies on an impressive instrumentation array and both methods and results are described in lucid language. As much as I would like to get further into a discussion of individual details of the study, it is already so dense and well crafted that I can not propose any big changes before I would recommend this for publication. I believe this work will be a crucial contribution to the community’s understanding of potential resilience of rock glaciers (and even debris covered ones) as well as when and how this resilience may come to an end. Future studies will hugely benefit from the ideas in monitoring and some of the concepts proposed in the Results to further this understanding. I am looking forward to this being part of future discussions on the topic.
There are very few general comments I have below and even fewer minor ones, as the authors have done an excellent job in language, syntax and copy editing already.
General:
L112: It is unclear what you mean with ‘massive ice’, please clarify. You mean depth? Or high content?
L130ff: Definitely important to point out the crucial role this laboratory has, I am just wondering if you could reduce the list of citations here to a few key publications that anyway then point to these further papers (e.g. ‘Hoelzle et al. 2002 and Scherler et al. 2014 and references therein, as well as at least 10 unpublished MSc theses’). The theses can not be directly accessed so am not sure how useful to cite here (or provide links to Uni repositories if possible). Also in references you call them ‘phdthesis’ and ‘mathesis’, if you keep them write it out so it is clear (PhD Thesis, MSc Thesis). Also you switch between ‘Umlaut’ spellings (e.g. ‘Ueber den Wärmehaushalt…’), keep it uniform.
L146: If reported in both enough if you just refer to one here.
L445: It wasn’t completely clear to me what ‘time period bias’ is supposed to mean. Can you explain that further?
L713: I am surprised this happens only ‘occasionally’ (Ts < Ta) – could you specify on how many nights or how many hourly measurements fulfilled that criterion? On debris cover we see this reversal relatively frequently.
L839: maybe better ‘daily as well as monthly’?
L851: I understand that the data was extremely difficult to retrieve and is valuable but I would invite the authors to consider making it available through a repository in the spirit of open science. I believe no scientist without the detailed field knowledge and knowledge of the setup would be able to take away any of your future research ideas before you are able to execute them. Conversely I believe that this dataset could be an extremely crucial contribution to our better understanding of cooling (or the future end of it) in such surface covers, and giving the opportunity to others who have experience in such environments to think along with this data, could accelerate our understanding even further.
Minor:
L44: ‘… exceptions being Rist and Phillips (2005) and Rist (2007)’
L85: You use the ‘sensu Oke’ reference already in L35, I think here it is redundant as this is already introduced.
L330: You mean ‘could not (!) test this bulk method’?
Citation: https://doi.org/10.5194/egusphere-2023-2109-RC1 -
AC1: 'Reply on RC1', Dominik Amschwand, 10 Dec 2023
Dear Emily Collier, dear referees
We wish to thank both reviewers for their thorough and constructive reviews. We respond to their raised points in the attached PDF document that we hope addresses their concerns. Thank
you for your consideration and we look forward to receiving your direction regarding the next steps of review.Dominik Amschwand on behalf of all co-authors
-
AC1: 'Reply on RC1', Dominik Amschwand, 10 Dec 2023
-
RC2: 'Comment on egusphere-2023-2109', Anonymous Referee #2, 31 Oct 2023
This manuscript presents a thorough analysis based on a substantial amount of field data. As such, it is not an easy read, but I cannot identify anything that I would suggest cutting (there is an amount of repetition that could be removed). The statements that the parametrisation “closed the monthly SEB” but “wind speeds had to be scaled to close the SEB” using a calibration parameter are alarming, but my comments are otherwise minor.
Figure 2
Photograph not mentioned in the caption.181
Could say that the Sicart et al. (2005) correction is for interference of solar radiation.214
The psychrometric constant here is the theoretical value for a ventilated wet bulb. Is that appropriate?272
Missing ) in C_p330
“could not test this bulk method”379
The modulus for downwards longwave radiation is unnecessaryFigure 7
First reference to this figure in the text comes after Fig. 11.
The black points on top of blue points are fine on screen but did not print well.Figure 12
The “Air flow speed proxy” axis needs an upper value.
The caption or legend should state that the dashed lines are latent heat fluxes.757
The use of parentheses and “respectively” make for a mangled sentence.872
Having given Ta as being measured in degrees Celsius in Table 1, need to state that this is a Kelvin temperature.905
The first \psi_h should be \psi_mCitation: https://doi.org/10.5194/egusphere-2023-2109-RC2 -
AC1: 'Reply on RC1', Dominik Amschwand, 10 Dec 2023
Dear Emily Collier, dear referees
We wish to thank both reviewers for their thorough and constructive reviews. We respond to their raised points in the attached PDF document that we hope addresses their concerns. Thank
you for your consideration and we look forward to receiving your direction regarding the next steps of review.Dominik Amschwand on behalf of all co-authors
-
AC1: 'Reply on RC1', Dominik Amschwand, 10 Dec 2023
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-2109', Anonymous Referee #1, 29 Oct 2023
Review Surface heat fluxes at coarse-blocky Murtel rock glacier (Engadine, eastern Swiss Alps) - Amschwand et al.
The authors attempt to describe the surface energy balance in the active layer of a rock glacier in the Swiss Alps with an impressively well thought out measurement setup within a cavity complemented by a well established monitoring setup of the atmosphere above. Over two years they show how the energy input is nearly completely turned over, explaining the resilience rock glaciers have versus potential drivers of mass wasting but also providing an understanding what parameters are crucial to keep in mind in future, to anticipate the potential decay of ground ice in such landforms under a changing climate. They are also able to test a variety of stability corrections and discuss their suitability to estimate turbulent fluxes efficiently and show suitable fits for already established models for a rock glacier case.
The study is extremely well thought out, relies on an impressive instrumentation array and both methods and results are described in lucid language. As much as I would like to get further into a discussion of individual details of the study, it is already so dense and well crafted that I can not propose any big changes before I would recommend this for publication. I believe this work will be a crucial contribution to the community’s understanding of potential resilience of rock glaciers (and even debris covered ones) as well as when and how this resilience may come to an end. Future studies will hugely benefit from the ideas in monitoring and some of the concepts proposed in the Results to further this understanding. I am looking forward to this being part of future discussions on the topic.
There are very few general comments I have below and even fewer minor ones, as the authors have done an excellent job in language, syntax and copy editing already.
General:
L112: It is unclear what you mean with ‘massive ice’, please clarify. You mean depth? Or high content?
L130ff: Definitely important to point out the crucial role this laboratory has, I am just wondering if you could reduce the list of citations here to a few key publications that anyway then point to these further papers (e.g. ‘Hoelzle et al. 2002 and Scherler et al. 2014 and references therein, as well as at least 10 unpublished MSc theses’). The theses can not be directly accessed so am not sure how useful to cite here (or provide links to Uni repositories if possible). Also in references you call them ‘phdthesis’ and ‘mathesis’, if you keep them write it out so it is clear (PhD Thesis, MSc Thesis). Also you switch between ‘Umlaut’ spellings (e.g. ‘Ueber den Wärmehaushalt…’), keep it uniform.
L146: If reported in both enough if you just refer to one here.
L445: It wasn’t completely clear to me what ‘time period bias’ is supposed to mean. Can you explain that further?
L713: I am surprised this happens only ‘occasionally’ (Ts < Ta) – could you specify on how many nights or how many hourly measurements fulfilled that criterion? On debris cover we see this reversal relatively frequently.
L839: maybe better ‘daily as well as monthly’?
L851: I understand that the data was extremely difficult to retrieve and is valuable but I would invite the authors to consider making it available through a repository in the spirit of open science. I believe no scientist without the detailed field knowledge and knowledge of the setup would be able to take away any of your future research ideas before you are able to execute them. Conversely I believe that this dataset could be an extremely crucial contribution to our better understanding of cooling (or the future end of it) in such surface covers, and giving the opportunity to others who have experience in such environments to think along with this data, could accelerate our understanding even further.
Minor:
L44: ‘… exceptions being Rist and Phillips (2005) and Rist (2007)’
L85: You use the ‘sensu Oke’ reference already in L35, I think here it is redundant as this is already introduced.
L330: You mean ‘could not (!) test this bulk method’?
Citation: https://doi.org/10.5194/egusphere-2023-2109-RC1 -
AC1: 'Reply on RC1', Dominik Amschwand, 10 Dec 2023
Dear Emily Collier, dear referees
We wish to thank both reviewers for their thorough and constructive reviews. We respond to their raised points in the attached PDF document that we hope addresses their concerns. Thank
you for your consideration and we look forward to receiving your direction regarding the next steps of review.Dominik Amschwand on behalf of all co-authors
-
AC1: 'Reply on RC1', Dominik Amschwand, 10 Dec 2023
-
RC2: 'Comment on egusphere-2023-2109', Anonymous Referee #2, 31 Oct 2023
This manuscript presents a thorough analysis based on a substantial amount of field data. As such, it is not an easy read, but I cannot identify anything that I would suggest cutting (there is an amount of repetition that could be removed). The statements that the parametrisation “closed the monthly SEB” but “wind speeds had to be scaled to close the SEB” using a calibration parameter are alarming, but my comments are otherwise minor.
Figure 2
Photograph not mentioned in the caption.181
Could say that the Sicart et al. (2005) correction is for interference of solar radiation.214
The psychrometric constant here is the theoretical value for a ventilated wet bulb. Is that appropriate?272
Missing ) in C_p330
“could not test this bulk method”379
The modulus for downwards longwave radiation is unnecessaryFigure 7
First reference to this figure in the text comes after Fig. 11.
The black points on top of blue points are fine on screen but did not print well.Figure 12
The “Air flow speed proxy” axis needs an upper value.
The caption or legend should state that the dashed lines are latent heat fluxes.757
The use of parentheses and “respectively” make for a mangled sentence.872
Having given Ta as being measured in degrees Celsius in Table 1, need to state that this is a Kelvin temperature.905
The first \psi_h should be \psi_mCitation: https://doi.org/10.5194/egusphere-2023-2109-RC2 -
AC1: 'Reply on RC1', Dominik Amschwand, 10 Dec 2023
Dear Emily Collier, dear referees
We wish to thank both reviewers for their thorough and constructive reviews. We respond to their raised points in the attached PDF document that we hope addresses their concerns. Thank
you for your consideration and we look forward to receiving your direction regarding the next steps of review.Dominik Amschwand on behalf of all co-authors
-
AC1: 'Reply on RC1', Dominik Amschwand, 10 Dec 2023
Peer review completion
Journal article(s) based on this preprint
Viewed
HTML | XML | Total | BibTeX | EndNote | |
---|---|---|---|---|---|
356 | 165 | 29 | 550 | 20 | 21 |
- HTML: 356
- PDF: 165
- XML: 29
- Total: 550
- BibTeX: 20
- EndNote: 21
Viewed (geographical distribution)
Country | # | Views | % |
---|
Total: | 0 |
HTML: | 0 |
PDF: | 0 |
XML: | 0 |
- 1
Cited
Dominik Amschwand
Martin Scherler
Martin Hoelzle
Bernhard Krummenacher
Anna Haberkorn
Christian Kienholz
Hansueli Gubler
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(15506 KB) - Metadata XML