Observations of Drifting Snow Using FlowCapt Sensors in the Southern Altai Mountains, Central Asia

Round 1

Reviewer 1 Report

The presented manuscript is a pioneering work on the description of snow drifts. As the authors of the manuscript rightly noted, there are very few experimental studies of snow drifts to date. This manuscript combines an experimental approach and a theoretical study of the movement of snow under the influence of wind. Very good results have been obtained. I am sure that the manuscript can be published. It is not clear only the highlighting of the text in red on page number 9. 

Author Response

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Reviewer 2 Report

Review of Observations of drifting snow using FlowCapt sensors in the southern Altai Mountains, Central Asia

 

General Comments

This paper presents useful information on the conditions under which drifting snow events occur in the southern Altai Mountains and on the magnitude of snow flux that occurs.

The paper should include a brief summary of the monthly mean climate normals at the Koktokay Snow Station for the December to April snow season including monthly mean total depth of freshly fallen snow in cm and mean rain depth in mm as well as monthly men temperature.

The major deficiency in the paper is the absence of measurements of the presence or absence of a crust at the snow surface during events and, if a crust is present, the resistive strength of the crust.  The authors need to explicitly acknowledge this deficiency and make clear that their conclusions apply only to crust-free snow conditions.

For example the statement in lines 311-312 that “We can arbitrarily infer that drifting snow will almost certainly occur once the wind speed (friction velocity) exceeds 7.0 m/s (0.4 m/s) “ must be qualified to sate that this statement applies only to crust-free conditions and that with a strong crust much higher wind speeds can occur with no drifting snow.

The discussion beginning on line 341 of the unusual conditions shown in Event 2  (no fresh snow event to create dry easily-moved snow on the surface and constant snow depth during the event) is puzzling as the explanation given for the constant snow depth at the observation point – the presence of a crust – does not explain where the drifting snow is originating.  It may be that there was a crust-free snow surface upwind of the observation site that was losing snow and that at the observation point snow transport was proceeding above a crusted-snow area with no net accumulation, just transfer.  In any case the authors should provide an explanation of where the drifting snow observed in event 2 originated.

The inclusion of Figure 6 and the description of a “hollowing” under a fixed-depth snow surface as was stated as being observed in the 2011-2012 snow season is an unnecessary complication. The occurrence of decreasing SWE while snow depth remains constant is contrary to almost all published descriptions of the behaviour of snowpacks – especially of snowpacks in humid climate areas.  The normal pattern is an increase in snow density with time during accumulation periods (from freshly-fallen snow relative-density of 0.1 to mature snowpack density of 0.3 – 0.4) followed by declining SWE and declining depth with constant density during melt.

I suggest that Figure 6 and the discussion associated with it be deleted from the paper. Comments should be restricted to what is known, or not known, about snow conditions at the observation site during Event 2.

I append  extracts from a paper with evidence of the usual pattern of temporal density variation to show how unusual the pattern shown on Figure 6 is.

 

 

 

Improvement to Figures

1. Since the focus of the paper is on three drifting snow events the three periods should be shown (by vertical lines for beginning and end time) in figures 2 (a) and 2 (b).
2. The shading for vapour pressure in Figure 2(b) should be darker – I found it very hard to see.

 

Editorial style editing suggestions:

1. Using SI units throughout. For example “8 feet” in Lines 56 and 58 should be 2.4 m
2. Substitute “snow incidents” for “snow disasters” throughout – “disaster” is too dramatic a term.
3. Round off numerical values from measurements to at most 3 significant figure and preferably 2 significant figures to reflect properly the accuracy of measurements.
4. In line 29 and elsewhere g/m²/s should be g/(m².s) or g m^-2s^-1

 

 

 

 

 

Skiles S.M., Painter T.  2017  Daily evolution in dust and black carbon content, snow grain size and snow albedo during snowmelt, Rocky Mountains Colorado.  Journal of Glaciology 63(237): 118- 132

 

 

 

 

 

 

 

 

 

 

                EXTRACT FROM PAGE 129 SKILES AND Painter 2017

 

Comments for author File: Comments.pdf

Author Response

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Reviewer 3 Report

The manuscript titled "Observations of drifting snow using FlowCapt sensors in the southern Altai Mountains, Central Asia" observes snow drift using ground observations. The study is interesting and worth publishing. Presently, the data is for quite a short period to assess it for different mentioned applications. In this case, the author may discuss the ground data in comparison to remote sensing snow (improved -https://doi.org/10.5194/essd-13-767-2021;

https://doi.org/10.5194/essd-12-345-2020; 

https://doi.org/10.3390/w12102681) data for a better understanding of snow.

Enhance the visibility of the legend and x,y labels in figure 4

The first paragraph (3 sentences) in the conclusion is a repetition and may be removed/deleted

Author Response

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