Reply on RC1

Using a wealth of different types of remote sensing imagery and meteorological data, Kouraev and colleagues provide a fascinating description of the development and disappearance of an ice ring in southern L. Baikal in early spring, 2020. In addition, the authors cleverly estimate the rotational velocity of the eddy current that created the ice ring by determining the rotational speed of ice floes moved by this current. The authors also describe changes in the visual features of the ice cover’s surface as weather conditions shift suddenly. With this paper, Kouraev and his colleagues not only extend and strengthen their previous work on the origin of ice rings in lakes, but they also provide excellent examples of how ice clarity and reflectance can change suddenly. Perhaps most importantly, however, their work demonstrates how the visible features of the ice surface on lakes are determined both by meteorological events occurring above the ice and water movements and heat flux occurring from below. This work will be useful not only to cryospheric scientists, but also to hydrodynamicists studying under-ice movement of eddies (or meddies) and to limnologists interested in measuring and predicting primary production under lake ice. The article is well illustrated and written in such a way that it is accessible to scientists from multiple sub-fields. This is no small feat given the highly technical nature of the fields of remote sensing and hydrodynamics.

Our item-by-item answers below are marked ">>". We have already prepared a new version of the manuscript to to address your suggestions and comments.
On behalf of all co-authors, sincerely Alexei Kouraev, Toulouse, 27 July 2021 RC1: 'Comment on tc-2021-146', Anonymous Referee #1, 14 Jun 2021 GENERAL COMMENTS Using a wealth of different types of remote sensing imagery and meteorological data, Kouraev and colleagues provide a fascinating description of the development and disappearance of an ice ring in southern L. Baikal in early spring, 2020. In addition, the authors cleverly estimate the rotational velocity of the eddy current that created the ice ring by determining the rotational speed of ice floes moved by this current. The authors also describe changes in the visual features of the ice cover's surface as weather conditions shift suddenly. With this paper, Kouraev and his colleagues not only extend and strengthen their previous work on the origin of ice rings in lakes, but they also provide excellent examples of how ice clarity and reflectance can change suddenly. Perhaps most importantly, however, their work demonstrates how the visible features of the ice surface on lakes are determined both by meteorological events occurring above the ice and water movements and heat flux occurring from below. This work will be useful not only to cryospheric scientists, but also to hydrodynamicists studying under-ice movement of eddies (or meddies) and to limnologists interested in measuring and predicting primary production under lake ice. The article is well illustrated and written in such a way that it is accessible to scientists from multiple sub-fields. This is no small feat given the highly technical nature of the fields of remote sensing and hydrodynamics.
>> We highly appreciate your positive evaluation of our work, thank you very much! My main suggestion is to clarify figure and table captions by providing additional information (see below).

SPECIFIC COMMENTS
--A more precise title might be: "Giant ice rings in southern Lake Baikal: multi-satellite data facilitate an analysis of ice cover dynamics and eddies under the ice" In the alternative title, the word 'evolution' is replaced with 'dynamics', and I encourage the authors to use alternative words such as 'dynamics' or 'development' instead of 'evolution' throughout the entire paper. For many scientists, the word, evolution, implies genetically-based inheritance, so replacing it with more appropriate terminology would increase clarity.
>> Good point. We have made changes to the manuscript (title and elsewhere). we also added there that "Radar altimetry do not provide images, but point measurements along the satellite track". We also indicate in this figure location of the Nizhneye Izgolovye Cape (see your later comment).  >>We would prefer to keep them separate, as Figure 5 shows the initial state, before ice break-up started in the eddy/ice ring region. Additional issue is that combining them will reduce their size and thus readability. Please also note that now we show Jason-3 data overlaid on satellite image on Figure 5a.
--Indicate in each of the figure captions for Figs. 5,7,9, & 11 that these are satellite images to distinguish these images from Fig. 8 which is a photo shot while standing on the ice and looking down at it. Also, consider marking where the direction north is in these figures so that the compass directions mentioned in the text are more readily interpreted in these images. >>Done. We put "satellite images" on caption for Figure 5 (Figures 7,9, and 11 have captions "same as Fig. XX" so it should be self-explanatory) and "Photo shots" for Fig. 8 caption.
-- Fig. 5 -Explain in caption what the white streaks are. Ice cracks? They are especially visible on 20 April. >>Done. We now also provide new text in the beginning of section 3 on how different surface types are seen on satellite images.
-- Fig. 6 -Very good display of meteorological data, but why doesn't this graph begin April 8th when the ice ring was first detected? I believe this figure begins on April 15 to demonstrate how the ice ring changed markedly in response to weather fluctuations. If that is true, consider stating this in the caption. >>We added to the figure caption: "Period is selected to represent meteorological conditions for satellite imagery presented in the paper" -- Fig. 7 -Are black areas open water in this figure, Fig. 9, and Fig. 11? Explain in caption. >>Done .
-- Fig. 8 -Indicate in caption that that these photos were taken while standing on the ice as opposed to having been taken from a satellite.--In caption, does the word 'limits' refer to edges? If so, replace 'limits' with 'edges' or 'boundaries'.--Last sentence of caption is redundant with information presented earlier in this caption. >>Done  Table 2 -State in the caption the year (2020) that these data represent. Also, "Total:219" in the column titled 'Angle of ice floe' is confusing. This is not a sum, because the numbers in that column do not total to 219. Instead, "Total:219" appears to be a restatement of the angle of ice flow on 27 April. Consider removing "Total:219". >>Done  Baikal. This is necessary because many readers will not be familiar with the location of Cape Nizhneye Izgolovye.->>Done, we also point to Figure 3 when now we show the location of Cape Nizhneye Izgolovye) -Also state in caption that this image depicts ice surface temperatures. >>Done, "Ice and land surface temperatures" (we also have the Cape in the image, so it is not only ice).
--The manuscript would benefit from redactory editing by a native English speaker. The use of articles (i.e., the, a, of) and verb tense need attention. Authors of scientific articles typically write about their study in the past tense but about the findings of others in the present tense. >>Done --line 52 -insert the word "Lake" or "L." in front of all lake names throughout the paper. >>Done --lines 36 & 37 -A citation or website seems appropriate at the end of these two sentences.  Table 1 so please clarify if this undocumented ring also occurred in Kultuk Bay. >>Yes, it was in Kultuk Bay, text changed.
--line 210 -Replace 'head' with 'western end' >>Changed to "extremities", as, for example, for the Cape Nizhneye Izgolovye it is a north-oriented end with narrow slopes, a kind of underwater canyon.