Why Is It Important to Consider Dust Aerosol in the Sevastopol and Black Sea Region during Remote Sensing Tasks? A Case Study

Round 1

Reviewer 1 Report

I am sorry. I tried hard to understand your analysis. I am not qualified to comment on the writing. But many unclear sentences and typos make it difficult to understand your explanations. Even the title is ambiguous to me. "in the tasks of remote sensing" seems too general to me. In my opinion, first, you have to edit and restructure the introduction and methodology parts (Section 1 and 2) to make clear what you are intended to do from your study. 

Author Response

Dear reviewer 1!

Thank you very much for the prompt review of our work!

Each of your comments has been taken into account and corrected, namely:

1) Sorry, for the incorrect presentation of the text of the article, with the help of a professional editor, the text was finalized, thanks for your comment;

2) The title of the article, according to your recommendations, has also been changed, it is specifically shown that dust aerosol was meant by absorbing aerosol; by remote sensing tasks, ocean color tasks were meant.

3) In general, the goals of the work are formulated differently, I hope the new version of the work meets all your comments.

The level of English has  been also corrected and the work has passed the final check and editing by a professional translator.

Best wishes

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors made detailed comparisons between clear day and dust day satellite retrieved spectral water leaving reflectances. The results, such as those presented in Fig. 5, are well worth for a journal publication. It would be great if the authors can ask a scientist, whose first language is English, to help re-write many sentences and paragraphs during the reviewing process, so that the manuscript is more readable. 

Fig. 5 revealed a fundamental problem with the NASA operational atmospheric correction algorithm for ocean color applications. It showed that, under dusty conditions, the NASA algorithm over-corrected aerosol effects for channels in the visible spectral region. This is a problem already lasted for over 20 years. Basically, the dust aerosols have strong absorption effects from UV to green to red, but the absorption effects are much decreased at 750 and 860 nm wavelength regions. The NASA algorithm used the 750 and 860-nm bands (where the dust absorption effects are already practically negligible) to estimate an aerosol model (Angstrom coefficient) and optical depth at 860 nm. Based on such Near-IR aerosol information, the NASA algorithm extrapolated the near-IR aerosol information to visible bands, and resulted in over-estimation of dust aerosol scattering effects for visible bands and negative water leaving values (Rrs), as shown in Fig. 5 of the manuscript.

The NASA L2 data product may contain enough info for users to figure out the NASA-estimated AOD values for visible bands. If so, so, it would be great if the authors could extract such AOD values from the NASA L2 data product, and then compare authors' dust spectral  measurements, as shown in Fig. 6 and 10, and to state the fact that the NASA algorithm over-estimated AOD values for visible bands.

Both Fig. 1 and Fig. 2 do not add much science values, and can be removed.

Author Response

Dear Reviewer 2!

Thank you very much for your valuable comments on our work.

Each of your comments has been taken into account and corrected, namely:

1) Sorry, for the incorrect presentation of the text of the article, with the help of a professional editor, the text was finalized, thanks for your comment;

2) We have supplemented graphs 6 and 10 with additional AOT spectra for the SPM handheld spectrophotometer for the studied dates based on your comments. I'm sorry, it's not possible to plot a spectrum from Ocean Color data, since only the AOT value at 869 nm is provided at level 2.

3) Figures 1 and 2 are excluded from the text, thank you very much for your comment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Aerosol particles has been found an issue in remote-sensing applications, especially in analysis of reflectance spectra. The authors compare clear day conditions against dusty episode with dust transported from the Sahara desert. The findings are interested and deserve publication in RS. Nevertheless, sand or dust particles typically contain non-absorbing mineral elements. The authors should therefore comment on material composition.

Please use Bouguer law instead of Booger's law. Line 361: should be Figure 6.

Fig. 6: what is the reason for almost identical slope of AOD for two different days under distinct atmospheric conditions?

Author Response

Dear Reviewer!

Thank you very much for your valuable comments on our work.

Each of your comments has been taken into account and corrected, namely:

1) Thank you for your additions about the mineral composition of the dust, we have added a link to an earlier work on the composition of dust over the Black Sea region. Specifically, this link (Hosphorus and silicon as markers of dust aerosol transfer over the Black Sea region DOI: 10.21046/2070-7401-2018-15-3-217-225)

2) We use Bouguer law instead of Booger's law, thanks for your comment;

3) Answer for Fig. 6: what is the reason for almost identical slope of AOD for two different days under distinct atmospheric conditions?

According to the results of long-term statistics of the study of the AOT spectral variation at this AERONET (Galata) station, it can be seen that this spectrum variation is typical for September in the west of the Black Sea.

Attached is an additional chart of average monthly AOT values for September 2017 at Galata station.

Thank you for your interest to our work!

Kind Regards

Author Response File: Author Response.pdf