Investigating Synoptic Influences on Tropospheric Volcanic Ash Dispersion from the 2015 Calbuco Eruption Using WRF-Chem Simulations and Satellite Data

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General comments

The aim of this paper is to simulate ash transport from Chile’s Calbuco volcano eruptions on April 22 and 23, 2015 using WRF-Chem. The model well-reproduced ash and SO₂ transport. The manuscript is well-written, the results are interesting and I think that the article must be published in "Remote sensing."  However, before publication I would suggest the authors to take into consideration the comments that I have listed below.

 

Main concerns:

- First of all, more details on local meteorological conditions at the beginning of the eruption event around the volcano could be of interest in the revised version of the manuscript. This could allow the reader to better check the initial situation.

 

-The analysis is based on the WRF-Chem model at 30 km resolution. The authors should discuss if the importance of local conditions at the beginning of the eruption does not require a higher resolution?

 

- Can the BTD methodology induce some uncertainties associated with high altitude cloud cover ?

 

- It would be easier to assess the performance of the model by reproducing the results depicted in Fig. 6 and Fig. 8 on the same figure.

 

- Is it relevant that the AOD seems to be constant on hundred kilometers in Fig. 8 or  the color gradation should be better chosen?

 

Minor comments

- Line 467 please replace "Figure ??".

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Overall, I believe this was a well written paper and was interesting to read how well WRF-Chem handled the dispersion of volcanic ash and SO2 in the southern hemisphere. I would have liked to see more evidence in the meteorology parameters on how much of the upward transport of materials was due to topography and how much was due to the energy from the eruption. How far up would particles go in the atmospheric column if there wasn't an eruption? While I believe the material presented could be publishable some of the conclusions need more meteorological evidence. 

Comments for author File: Comments.pdf

Author Response

Please see the attachmen

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In their manuscript "Investigating Synoptic Influences on Tropospheric Volcanic Ash Dispersion from 2015 Calbuco Eruption Using WRF-Chem Simulations and Satellite Data" the authors explore the atmospheric state and development during the eruption period that lead to ash transport over South America. This topic is interesting for meteorologists as well as volcanologists and others, so that an interdisciplinary journal like Remote Sensing is a good choice and I suggest considering it as appropriate for publication after some minor changes. The main issue I have with this manuscript is, that I had a very hard time understanding chapter 2.2 (synoptic analysis) in text and figures 1-4. My background is in volcanology, not meteorology, so I do not have the expertise to interpret the figures myself. Features described in the text (although sometimes referring to specific panels in figures) were not obvious from the figures. I would suggest adding either a schematic interpretation to each figure or annotations that highlight the discussed features in the figures. It is a small change that might clutter the images, but for non-meteorologists, this change is crucial for understanding. The mentioned chapter is the most important in this manuscript as it shows the complicated atmospheric flows around the Andes and explains the complex dispersion pattern for volcanic ash of Calbuco (and any other volcano in the Andes). Besides this main point I do have some minor specific and technical comments, listed below.

Specific comments:
- The manuscript (especially the abstract) contains a vast amount of acronyms, of which many are not defined on first occurrence (e.g. line 5 GOCART and NCEP-FNL). In the introduction acronyms are used, which are defined in later chapters (l.42, defined in l.461 and l.77, defined in 248). A further example is in chapter two (ESP, l.124, defined in l. 256). The use of acronyms is convenient for authors and when those acronyms are either self-explaining or used in general. For a reader, especially from a slightly different scientific field, acronyms hinder understanding. With this in mind, I would also suggest to rewrite l.113-114. I did not list all of the acronyms here.
- The introduction would benefit from a geographic and topographic map of the region (like figure 5) that includes all borders, lists all countries (and the mentioned cities) and highlights the location of Calbuco Volcano.
- l.143 as you already have an acronym (COL), I suggest highlighting it in the respective figure (also in later times). The same would be beneficial for the "long wave trough" (l.148), the "amplifying shortwave" (l.149) and HCV (l.172).


technical comments:
- Figures 1-4 show too many details. Leave the countries borders, but remove region and state borders. This will declutter the figures and make room for necessary annotations (see above).
- Table 2: when only S1 and S2 are used, why are the others listed? They are not mentioned in the text.
- Figure 5: can you plot the grid? If you include a geographic/topographic map as figure 1, you can also restrict to the actual domain.
- l.287: "it is allowed a" is passive voice, please rewrite
- l.289: move definition of acronym from l.292 here
- l.435: something is wrong with this citation
- l.467: missing figure label
- Figures 9-12: for a comparison, please indicate the extend of the smaller map within the respective larger. And what about using the same colour bar and colour range?
- l.475: ... the Pacific Ocean with ...

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for going through and making the suggested edits. I feel that the paper has greatly improved both in the understanding as well as the impact of the conclusions.