Analyzing glacier retreat and mass balances using aerial and UAV photogrammetry in the Ötztal Alps, Austria

Geissler, Joschka; Mayer, Christoph; Jubanski, Juilson; Münzer, Ulrich; Siegert, Florian

doi:https://doi.org/10.5194/tc-15-3699-2021

Articles | Volume 15, issue 8

https://doi.org/10.5194/tc-15-3699-2021

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

https://doi.org/10.5194/tc-15-3699-2021

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

Articles | Volume 15, issue 8

Research article

|

06 Aug 2021

Research article |

| 06 Aug 2021

Analyzing glacier retreat and mass balances using aerial and UAV photogrammetry in the Ötztal Alps, Austria

Joschka Geissler, Christoph Mayer, Juilson Jubanski, Ulrich Münzer, and Florian Siegert

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Final revised paper (published on 06 Aug 2021)
Preprint (discussion started on 27 Oct 2020)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review of Geissler et al. The potentials of high-resolution photogrammetry for analyzing glacier retreat in the ÖtztalAlps, Austria', Ben Pelto, 15 Dec 2020
- AC1: 'AC to tc-2020-263-RC1', Joschka Geissler, 06 Jan 2021
RC2: 'Review of ‘The potentials of high-resolution photogrammetry for analyzing glacier retreat in the Ötztal Alps, Austria’ by Geissler and co-authors.', Anonymous Referee #2, 12 Jan 2021
- AC2: 'Reply on RC2', Joschka Geissler, 14 Jan 2021

Peer-review completion

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

ED: Publish subject to revisions (further review by editor and referees) (18 Jan 2021) by Etienne Berthier

AR by Joschka Geissler on behalf of the Authors (26 Feb 2021) Author's tracked changes

ED: Referee Nomination & Report Request started (04 Mar 2021) by Etienne Berthier

RR by Ben Pelto (08 Mar 2021)

RR by Anonymous Referee #2 (06 Apr 2021)

Suggestions for revision or reasons for rejection

I have looked at ‘Author's Response’ and ‘Author's tracked changes‘

It was a bit challenging to do this review for several reasons:
- not all changes are visible in the track changes version, e.g. several of the new references are not marked with track changes, neither in the text nor in the reference list.
- I would have preferred to have an author response sorted on the reviews, it would make it easier for the reviewer to check it, as now it is a mix in a table
-it is confusing with two figures of each figure, here it could be clearer what is the updated figure.
-much rewritten text in a track change mode makes it a bit hard to assess it
-the manuscript seems not to be proofread, not according to track changes.
-the writing is still confusing many places, also in new written parts.

For the next time, I suggest the authors add both a track changes version and a clean version to make it easier for the referee.
I also find it a bit strange that in the two author responses (AC1 and AC2) available on https://tc.copernicus.org/preprints/tc-2020-263/, the authors state: ‘…Indeed, most of your proposed changes of the manuscript are implementable and will not take too much time. We agree, that those small corrections will improve our manuscript and would therefore be happy to implement the following changes of the manuscript.’ and ‘…We are convinced that those corrections and improvements will not take too long and will further improve the quality of our manuscript’(AC2).

Of course, one does not want to use more time than needed, on the other hand it seems the authors do not understand that this is a major revision and that time is required. I have not checked everything in the ms, so cannot approve of the paper as is.

Title:

The authors write: ‘Thank you for your valuable suggestion, we discussed your feedback and adapted our title accordingly’. They did not adapt the title accordingly. The title is changed, but not as suggested, it is strange that they then write accordingly. Such an example of adaptation is confusing and not very convincing.

Line 35: ‘The availability of high -resolution multi-temporal digital aerial imagery for most of the glaciers in the Alps will provide a more comprehensive and detailed analysis of climate change- induced glacier retreat.’ Is it really the availability of images that provide .. I would rather say ‘the availability of …. images provide opportunities for a more comprehensive and detailed analysis of glacier retreat.’

Line 67: the authors here write on airborne laser scanning and digital photogrammetry as standard methods, but here one could also differ between data sources (aerial and satellite imagery and lidar) and methods. One can also combine various data sources to obtain geodetic mass balance so this section could been improved in my opinion

Line 68. Present tense on published data, e.g. are, but here you could also add newer literature, this is 20 years old.

Line 70. But the methods can be combined so don’t understand this reasoning, Belart et al (2019) combines several DEMs.

Line 77. It is common to apply a correction to compare geodetic and glaciological, this is explained in Zemp et al. (2013) and many other papers, e.g. Andreassen et al (2016) (https://tc.copernicus.org/articles/10/535/2016/)

Line 82-83. I still don’t understand what is unique by this, using meteorological data for correction and using drone data is not new. See point above. Maybe it is just clumsy writing, but I expect more of the revised version.

Line 84. Here you write this calibration but the line before does not talk about calibration.

Line 91. Here you refer to glaciated, in the abstract you refer to glacierized. This is not the same. Glaciated is often referred to as covered by glaciers in the past.

Line 137. I would say the uncertainty can be higher than 1 cm for stake readings when surface is uneven (ice).

Line 153. Why separate ablation area and accumulation are, is it not ablation and accumulation on the entire glacier?

Line 204. It is common to use average glacier area, e.g. Zemp et al (2013) that you refer to. This will impact the results and you need to recalculate it to compare with glaciological balance.

Line 213. The glaciological data is mentioned in 3.2. you could define ELA in chpter 3.2. on line 144 and write how it is calculated from the equilibrium line. And remove ‘For the Vernagtferner, the altitude of the equilibrium line altitude (ELA) is known from intense glaciologic surveys on an annual basis (BAdW, 2019).’

Line 214, you mean the mean ELA for these three periods? Rewrite: ‘The observed ELA of Vernagtferner varied between xxxx and yyyy in the study period, the mean ELA was … for the period ….

The variation from 3217 to 3278 to 3237 is very small so how much will the calculation impact the result? Could comment in the text.

Line 224. The data should be homogenised, not only an error estimation. A bit confusing writing.

Line 229. Calibration is done when needed so you should comment in the result if this is needed – after comparing the results. so state her that you homogenised the data and quantified the errors.

Line 259. This method -> be specific, write DDF method if this is what you mean. Details on your work should be in the paper.

Line 262. Do you really calculate the geodetic mass balance for the correction periods, do you now calculate a correction? In table 2 you refer to correction parameters, I would liked to see the result.

Line 315. Fig 4. Why not have 2009 and 2018 outlines of all glaciers on this figure. The font is not very readable.

Fig. 5. The font not very readable. Which glacier tongu in the center-right, add name of ID.

Fig. 6. This figure text is very short.

Fig. 9. Is this the corrected values?

Fig. 10. What is the scale used in this figure, it is difficult to see the different categories. Is it uneven colour scale such as rainbow map (https://www.nature.com/articles/s41467-020-19160-7)?
It could be better to have the scale on the figure or use discrete classes, e.g. 8 or 10 classes.
The table could be taken out and showed in a table.

Line 454. Here you talk on heigh changes but the figure shows changes in m w.e.

Line 461. ‘All glaciers’ are written two times in this sentence, remove one occurrence.

Line 518. It is not easy to see the dead ice body from figure 4, even if it is marked. I suggest to show it in a subset figure, e.g. add a frame so it is possible to see it.
Line 538. It is the resulting geodetic mb that must be considered with caution.

Line 540. Why do you not use it for the other glaciers then, or try to estimate it with the data you have on ELA and orthophotos or retrieve ELA using satellite images?

Line 636. How does your method compare to other methods such as mass balance modelling being used to correct for acquisition dates?

Line 645. What about Lidar surveys? And aerial imagery with poorer contrast (e.g. ice caps)?

Line 648. But this was only done for one glacier. Using UAV in addition to aerial imagery for all these glaciers is not manageable. And you need to show how you can use information from one glacier to the others to make this argument valid.

Appendix or supplementary material in the end of ms. As it is only one table you could have it in the manuscript itself as ordinary table.

Table text above the table. Are this corrected values? You need to add more info.

Use dot (.), not comma (,) as decimal operator throughout in paper

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ED: Publish subject to revisions (further review by editor and referees) (08 Apr 2021) by Etienne Berthier

AR by Joschka Geissler on behalf of the Authors (04 May 2021) Author's response Author's tracked changes Manuscript

ED: Publish subject to minor revisions (review by editor) (21 May 2021) by Etienne Berthier

AR by Joschka Geissler on behalf of the Authors (18 Jun 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (29 Jun 2021) by Etienne Berthier

AR by Joschka Geissler on behalf of the Authors (02 Jul 2021)

Short summary

The study demonstrates the potential of photogrammetry for analyzing glacier retreat with high spatial resolution. Twenty-three glaciers within the Ötztal Alps are analyzed. We compare photogrammetric and glaciologic mass balances of the Vernagtferner by using the ELA for our density assumption and an UAV survey for a temporal correction of the geodetic mass balances. The results reveal regions of anomalous mass balance and allow estimates of the imbalance between mass balances and ice dynamics.