Applying artificial snowfall to reduce the melting of the Muz Taw Glacier, Sawir Mountains

Wang, Feiteng; Yue, Xiaoying; Wang, Lin; Li, Huilin; Du, Zhencai; Ming, Jing; Li, Zhongqin

doi:https://doi.org/10.5194/tc-14-2597-2020

Articles | Volume 14, issue 8

https://doi.org/10.5194/tc-14-2597-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/tc-14-2597-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 14, issue 8

Research article

|

13 Aug 2020

Research article |

| 13 Aug 2020

Applying artificial snowfall to reduce the melting of the Muz Taw Glacier, Sawir Mountains

Feiteng Wang, Xiaoying Yue, Lin Wang, Huilin Li, Zhencai Du, Jing Ming, and Zhongqin Li

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Final revised paper (published on 13 Aug 2020)
Preprint (discussion started on 18 Dec 2019)

Interactive discussion

Status: closed

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

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RC1: 'Comments and suggestions for revision', Suryanarayanan Balasubramanian, 04 Feb 2020
- AC1: 'Reply to the comments of Suryanarayanan Balasubramanian', F. Wang, 03 Mar 2020
RC2: 'Review of Wang et al.', Samuel Morin, 04 Feb 2020
- AC2: 'Reply to the comments of Samuel Morin', F. Wang, 03 Mar 2020

Peer-review completion

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

ED: Reconsider after major revisions (further review by editor and referees) (04 Mar 2020) by Xavier Fettweis

AR by F. Wang on behalf of the Authors (06 Mar 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (10 Mar 2020) by Xavier Fettweis

RR by Samuel Morin (26 Mar 2020)

Suggestions for revision or reasons for rejection

Review of a revised version of « Applying artificial snowfalls to reduce the melting of the Muz Taw Glacier, Sawir Mountains », by Wang et al., by Samuel Morin, 26 March 2020.

The manuscript by Wang et al. has been revised following the first peer-review step. This has led to improvements and clarifications of the manuscript. I thank the authors for performing these clarifications. I however consider that this revision has revealed a major flaw in the study, which, to me prevents publication of the manuscript in The Cryosphere. Indeed, with the information provided, it appears almost impossible to assess the role of artificial snowfalls, and distinguish them from natural precipitation.

Indeed, reading Page 7, line 131, we read :
“First, we used the radar to identify local convective clouds in the background synoptic clouds and measured the orientation, height and distance of the convections for determining the time and area for performing artificial precipitation seeding. And then we chose most favourable timing to ignite the silver-iodide smog generators (Figure 3a) and let the silver-iodide (AgI) particles as catalyzer help forming amounts of artificial ice nuclei (Figure 3b) to absorb more water vapour and promote to form precipitations.“

From this statement, it appears obvious that artificial snowfall can only proceed under circumstances where natural precipitation is plausible. This is confirmed by the statement on Page 10, line 210 :

“4.1 The amounts and form of the artificial precipitations
Figure 5a shows the hourly temperature and precipitations recorded by the AWS from 12 to 24 Aug 2018. There were some natural precipitations during 12 – 14 Aug, while except this and that in the experiment days, the whole period of 12 – 24 Aug was sparse in precipitations. Artificial-precipitation experiments were carried out on 19, 22 and 23 Aug. The amounts of precipitations were 6.2 mm on 19th, 1.3 mm on 20th, 1.8 mm on 22nd and 10.6 mm on 23rd, respectively. Most snowfalls were observed during midnights and early mornings. There were significant precipitation amounts recorded by the AWS every single time after we ignited the smoke generators (Figure 5b). We could not completely distinguish the artificial precipitations from the natural ones if they were simultaneously mixed in all these events. However, the co-occurring of the significant snow falling with the AgI smoke allows supposing that we were producing artificial precipitations.”

The last line seems to be a somewhat circular argument : by design, artificial precipitation experiments were only activated under circumstances favorable for natural precipitation. It is therefore unsurprising that precipitation occurred simultaneously with times when AgI smoke was produced.

My understanding is thus that it is virtually impossible to distinguish natural from artificial precipitation, and there is no solid evidence provided, in the manuscript, which would make this point stronger. This weakness is not mentioned in the abstract or conclusion, hence I see a risk that, if published, this manuscript would be used as factual information claiming that artificial precipitation is effective to reduce the mass loss of glaciers. This is a potentially very significant result, and this requires that the evidence upon which it is based is robust.

Based on the present state of the manuscript, and unless the authors can provide robust and unambiguous evidence (e.g. using independent measurements from nearby mountains exposed to the same synoptic system but not exposed to the AgI cloud) that artificial and natural precipitation can be partitioned, I would recommend that this manuscript is not accepted.

Note that I have a number of other, less significant comments, which I can provide upon request by the Editor, in the case where the editorial process proceeds.

Yours sincerely,
Samuel Morin

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ED: Reconsider after major revisions (further review by editor and referees) (27 Mar 2020) by Xavier Fettweis

AR by F. Wang on behalf of the Authors (02 May 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (05 May 2020) by Xavier Fettweis

RR by Samuel Morin (27 May 2020)

Suggestions for revision or reasons for rejection

Review of second revision of “Applying artificial snowfalls to reduce the melting of the Muz Taw Glacier, Sawir Mountains” by Wang et al.
Samuel Morin, 24 May 2020.

Wang et al. have performed extensive modifications on their manuscript, in order to address a flaw identified during the previous review round. Indeed, the revised manuscript clearly recognize the difficulty in partitioning natural and artificial precipitation in cloud seeding experiments, and the revised manuscript provides a more balanced overview of this difficulty for the present experiment.

I have no more major reservations on this manuscript, although there are several instances, as indicated before, where I think the manuscript deserves to be improved and made clearer. I expect that the editing process following the potential acceptance of the manuscript will provide an opportunity to clarify the wording and remove potential remaining ambiguities. Please find below some suggestions and comments, which can hopefully be quickly addressed by the authors.

Page 2, line 13: The statement “decreased by 32 to 41 mm w.e.” can be misleading. I suggest rephrasing into “decreased by between 32 and 41 mm w.e.” and propagate this change throughout the manuscript.

Page 3, line 41 to 43: the statement about ski resorts near Grenoble is totally extraneous to the topic of this publication, I strongly suggest to remove it, as it makes little sense in the logical flow of information.

Page 3, line 46: The term “administrative” is not appropriate here, I suggest deleting, or replace by a more adequate term (“technical” ?)

Page 3, line 57: This paragraph starts abruptly about the toxicity of cloud seeding material, without any introduction about cloud seeding and whether this has been tested for reducing glacier mass loss. I strongly suggest that some statements are added priori to this paragrapgh, in order to introduce cloud seeding in general, and whether this has been tested for reducing glacier mass loss in previous study (apparently not), and indicate that this is the purpose of this study. The paragraph from Page 3, line 57 to Page 4, line 63, could then be positioned at the end of the paragraph from Page 4, line 65 to Page 4, line 75. All in all, the flow of the information needs to be carefully checked, in order to guide the reader through the introduction in a meaningful way.

Page 6, line 117: The paragraph from Page 6, line 117 to Page 6, line 125, does not specifically belong to the subsection “3.1 Artificial-precipitation experiment” but rather another subsection to be added before it, which could be referred to as “3.1 Meteorological radar observations”.

Page 6, line 128: “We” in “We distributed” is unclear. In previous statements, it was indicated that the smog generators were installed by the local meteorological service (Page 4, line 80 “These smog generators were set up there by the local meteorological service for artificial-precipitation tasks”. It becomes unclear whether the smog generators were installed there already, and used by opportunity to test whether they could be efficient in reducing glacier mass loss, are if they were installed specifically for the purpose of the experiment.

Page 12, line 291: I suggest that it is always stated which AWS is dealt with, when referred to in the text. Only referring to “AWS” is unclear because it could refer to the “grassland” or “ELA” AWS. I also suggest, for clarity, that the “ELA AWS” is in fact referred to as the “glacier AWS”. I believe this will increase the overall readability.

Page 16, line 361: I suggest replacing “less” by “lower”.

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ED: Publish subject to minor revisions (review by editor) (27 May 2020) by Xavier Fettweis

AR by F. Wang on behalf of the Authors (29 May 2020) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (16 Jun 2020) by Xavier Fettweis

AR by F. Wang on behalf of the Authors (17 Jun 2020) Manuscript

ED: Publish as is (02 Jul 2020) by Xavier Fettweis

AR by F. Wang on behalf of the Authors (09 Jul 2020)

Short summary

How to mitigate the melting of most mountainous glaciers is a disturbing issue for scientists and the public. We chose the Muz Taw Glacier of the Sawir Mountains as our study object. We carried out two artificial precipitation experiments on the glacier to study the role of precipitation in mitigating its melting. The average mass loss from the glacier decreased by over 14 %. We also propose a possible mechanism describing the role of precipitation in mitigating the melting of the glaciers.