VIIRS after 10 Years—A Perspective on Benefits to Forecasters and End-Users

Round 1

Reviewer 1 Report

I reviewed the paper based on its stated goal: to provide an overview of many of the user-oriented products that have been developed by VIIRS. The paper is a review paper and does not address a research question. Instead, it asks: 'over the last 10 years of VIIRS, what user-oriented products have been developed for forecasting?'

I believe there can be more additions to the text that will help the paper reach its goal. The paper is missing a basic explanation of VIIRS and assumes some level of prior knowledge by the reader. For example, a basic table listing the wavebands and perhaps a list of common products and novel (unique) products or applications would be useful.  However, this review paper is lacking a sufficient review and I suggest that more text and work be done to that end. If not, I suggest rewording the title to make it less broad.

The paper describes a few case study examples of forecasting with VIIRS that appear in other papers by themselves, but are presented here altogether to highlight the capabilities of VIIRS and motivate future work. Because the review focuses on unique capabilities of VIIRS, it's unclear what the common capabilities are and how those are used (or not) by e.g., NWS. More information to that end would be helpful, especially to understand why VIIRS data are or are not being used for forecasting. 

The authors should include at minimum, a summary table describing the capabilities of VIIRS and how different wavebands can give different applications. For example, the authors focus on the terrestrial US for the most part and do not include any open ocean applications (for which there are many). There are many wavebands on VIIRS, and the focus of this article does not cover the whole spectrum. The introduction should be rewritten to focus the paper on the specific forecasting abilities of VIIRS as well as the gaps and future work that should be addressed.

Section 3, the Forecast Benefits of VIIRS, could have an overview paragraph before going into the specific benefits that describe the basic ways in which VIIRS data are used for forecasting. The unique aspects mentioned (snowmelt, sea spray, cloud microphysics) are not the only forecasting examples I suspect. For a paper that is based on 10 years of VIIRS studies, I found the references to be very thin. 

I'm not sure what's needed for reprinting the opinions of those who are quoted - did they give permission to be cited in this study? 

Similarly, do the authors have rights to the figures printed in this paper? I suggest digitizing the data and repotting so the figures match each other in style and quality. I suggest the figures be remade so all are of the same quality, and the authors need to ensure they have permission to reprint figures. There are many services that exist for free that can digitize data from old figures so that new and improved visuals can be constructed from the same data source (e.g., Web Plot Digitizer). 

The conclusions and discussion should highlight the uncertainties in VIIRS observations and how they may be used in forecasting. Currently there is no discussion of error or radiometric uncertainty, and we know there are both random and systematic errors in VIIRS. For example:   Bisson, K. M., Boss, E., Werdell, P. J., Ibrahim, A., Frouin, R., & Behrenfeld, M. J. (2021). Seasonal bias in global ocean color observations. Applied optics, 60(23), 6978-6988.
  Chen, H., Sun, C., Xiong, X., Sarid, G., & Sun, J. (2021). SNPP VIIRS day night band: ten years of on-orbit calibration and performance. Remote Sensing, 13(20), 4179.   Errors and biases are important to consider when conducting forecasting experiments, and some attention to this should be paid in the text.    Additionally, I found the paper lacking other applications to direct future work, and I think a targeted 'future work' section is warranted given the scope and aim of the paper. The current future work section does not sufficiently outline what science we can expect (or should aim for) in the coming 10 years.

It would be useful if the authors point to specific uses in the future that are specifically enabled by VIIRS, compared to e.g., the upcoming PACE mission or the current MODIS-Aqua. 

Besides applications of VIIRS data, the readers should get a basic sense for the uncertainties and performance of VIIRS data, in my opinion. I suggest the authors include a section and statistics for VIIRS performance or validation assessments. 

For a review paper especially, there are very thin references given and more references or even a list of 'business as usual' VIIRS forecasting versus 'unique' VIIRS forecasting would be very helpful to see. I expected to see many more references that link to the many applications and basic stats of VIIRS data, for example :   Wolfe, R. E., Lin, G., Nishihama, M., Tewari, K. P., Tilton, J. C., & Isaacman, A. R. (2013). Suomi NPP VIIRS prelaunch and on‐orbit geometric calibration and characterization. Journal of Geophysical Research: Atmospheres, 118(20), 11-508.   Wang, W., Cao, C., Shao, X., Blonski, S., Choi, T., Uprety, S., ... & Bai, Y. (2022). Evaluation of 10-Year NOAA/NASA Suomi NPP and NOAA-20 VIIRS Reflective Solar Band (RSB) Sensor Data Records (SDR) over Deep Convective Clouds. Remote Sensing, 14(15), 3566.
  Liu, L., Zhang, X., Yu, Y., Gao, F., & Yang, Z. (2018). Real-time monitoring of crop phenology in the Midwestern United States using VIIRS observations. Remote Sensing, 10(10), 1540.
  Yu, B., Shi, K., Hu, Y., Huang, C., Chen, Z., & Wu, J. (2015). Poverty evaluation using NPP-VIIRS nighttime light composite data at the county level in China. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 8(3), 1217-1229.

 

Author Response

Thank you for your careful and attentive review of our manuscript.  Your review provided many key insights into the focus of the paper that required revision, and we appreciate your contribution to improving the paper's intent and focus.  

In general, we have revised the manuscript to tighten the focus on the user-oriented products to make it less broad, as suggested.   Many of the concerns raised were related to the broadness of the previous manuscript - with the new revision, we hope this addresses and ameliorates the bulk of the concerns.

As this manuscript is part of a larger, VIIRS-focused special issue of Remote Sensing, we feel that a certain level of familiarity with VIIRS will be evident.  Likewise, with a narrowed scope with a specific focus on unique and anecdotal case studies, in the context of a review issue, we feel that many of the requested edits would now be beyond the scope of the revised manuscript. 

To address your concerns specifically:

I believe there can be more additions to the text that will help the paper reach its goal. The paper is missing a basic explanation of VIIRS and assumes some level of prior knowledge by the reader. For example, a basic table listing the wavebands and perhaps a list of common products and novel (unique) products or applications would be useful. 

While we feel that a broad explanation of VIIRS in general is beyond the scope of this paper, we have added additional information about relevant wavebands and the manner in which they are used for both the unique and common retrieval methods discussed.  A special focus on improving the description and manner of use (in a forecast sense) has been added to the RGB products discussed in Section 3 as a result of your suggestions.

However, this review paper is lacking a sufficient review and I suggest that more text and work be done to that end. If not, I suggest rewording the title to make it less broad.

The title, abstract, and introduction to the paper have been extensively rewritten to refocus the manuscript and avoid overly broad intent.

Because the review focuses on unique capabilities of VIIRS, it's unclear what the common capabilities are and how those are used (or not) by e.g., NWS. More information to that end would be helpful, especially to understand why VIIRS data are or are not being used for forecasting. 

Additional language describing the use of VIIRS in forecasting has been added to Section 3 as requested.

The authors should include at minimum, a summary table describing the capabilities of VIIRS and how different wavebands can give different applications.

With the refocus of the paper towards specific, anecdotal use cases, we have instead added specific information related to wavebands for the unique retrievals described.  

For example, the authors focus on the terrestrial US for the most part and do not include any open ocean applications (for which there are many). There are many wavebands on VIIRS, and the focus of this article does not cover the whole spectrum.

The manuscript has been revised to more clearly reflect the intent of the work, which is not to be a comprehensive review of all VIIRS products.  

The introduction should be rewritten to focus the paper on the specific forecasting abilities of VIIRS as well as the gaps and future work that should be addressed.

The introduction has been revised as suggested.

Section 3, the Forecast Benefits of VIIRS, could have an overview paragraph before going into the specific benefits that describe the basic ways in which VIIRS data are used for forecasting.

A comprehensive introduction to Section 3 has been added, as suggested.

The unique aspects mentioned (snowmelt, sea spray, cloud microphysics) are not the only forecasting examples I suspect. For a paper that is based on 10 years of VIIRS studies, I found the references to be very thin. 

The intent of the section is to focus on anecdotal use of unique VIIRS observations for specific forecast cases.  Additional information on the products used, including references, have been added at the reviewer's suggestion.

I'm not sure what's needed for reprinting the opinions of those who are quoted - did they give permission to be cited in this study? 

We have received explicit, written permission to reprint the opinions gathered for this study.  The text in Section 4 has been revised to focus on NWS roles, with the names moved to the Acknowledgements section, to clean up the text.

Similarly, do the authors have rights to the figures printed in this paper? I suggest digitizing the data and repotting so the figures match each other in style and quality. I suggest the figures be remade so all are of the same quality, and the authors need to ensure they have permission to reprint figures. There are many services that exist for free that can digitize data from old figures so that new and improved visuals can be constructed from the same data source (e.g., Web Plot Digitizer). 

The reviewer brings up two issues with the figures present in the third-party review section: one of permission, and one of figure quality.  We had explicit permission from workshop contributors to re-use their presentation materials (including figures) in a workshop summary publication.  We did not have permission to edit their work in that republication.  With the timeline of this review, it was not possible to contact all of the contributors and get either: reworked figures to address reviewers concerns, or get the raw data (and permission) to reprocess the images locally. 

Because of this, the text in this section has been refocused on more general outcomes from the workshop, with anecdotal cases as before, but no longer requiring Figure 6-9 (which could not be reworked to address the reviewer's concerns.)

The conclusions and discussion should highlight the uncertainties in VIIRS observations and how they may be used in forecasting. Currently there is no discussion of error or radiometric uncertainty, and we know there are both random and systematic errors in VIIRS.  Errors and biases are important to consider when conducting forecasting experiments, and some attention to this should be paid in the text.    

With the revised focus on specific use cases, we feel that a comprehensive review of uncertainty in VIIRS is beyond the scope of the intent of this manuscript.  Errors and biasing have been discussed in other review publications and are cited in this manuscript for reference.

Additionally, I found the paper lacking other applications to direct future work, and I think a targeted 'future work' section is warranted given the scope and aim of the paper. The current future work section does not sufficiently outline what science we can expect (or should aim for) in the coming 10 years.  It would be useful if the authors point to specific uses in the future that are specifically enabled by VIIRS, compared to e.g., the upcoming PACE mission or the current MODIS-Aqua.

Similarly, the focus of the paper is on unique observations from the previous ten years of VIIRS observations.  We feel that extensive speculation on the future of VIIRS with respect to current or planned missions is beyond the scope of this manuscript.

Besides applications of VIIRS data, the readers should get a basic sense for the uncertainties and performance of VIIRS data, in my opinion. I suggest the authors include a section and statistics for VIIRS performance or validation assessments. 

Likewise, in our opinion, a comprehensive section including statistics about VIIRS performance and validation would be beyond the scope of this paper, given the context of the special issue it is appearing in.

For a review paper especially, there are very thin references given and more references or even a list of 'business as usual' VIIRS forecasting versus 'unique' VIIRS forecasting would be very helpful to see. I expected to see many more references that link to the many applications and basic stats of VIIRS data,

Again, with the refocus of the paper to a less broad scope, a comprehensive review of literature would be beyond the intent of the manuscript.

Your review of the manuscript revealed many changes that we feel were needed, including a critical refocus of the scope of the manuscript.  It is our intent that this new refocused manuscript addresses all of the concerns offered about the previous version, which was sufficiently broad so as to require the additional work suggested.  We hope you agree that the new focus, one on anecdotal examples which are unique and hopefully compelling to the reader, will suffice given the context of the special issue.  Again, thank you for your careful and considerate editing, and we appreciate the time spent on the manuscript.

Reviewer 2 Report

To the authors, 

please, see the attached file.

Comments for author File: Comments.pdf

Author Response

Thank you for your thorough edits to our manuscript!  To address your suggestions:

Lines 9-10: ‘’...a wide range of applications, operational and research-based, ...’’

Maybe, better to add ‘’both’’: ...a wide range of applications, both operational and research- based, ...

The text has been revised to add 'both'.

Line 128:’’ The RGB takes advantage of the near-IR channel characteristics that a snowpack made up ..’’

This is not clear. Please, rephrase this sentence.

The description of the snow product has been replaced with much more comprehensive and clearer language.

3.1. VIIRS Snowmelt RGB

Looking at Figure 1, it is not so clear where is North Dakota for a non-U.S. reader. It would be better to add labels as in Figure 5.
Moreover, the two panels show different portions of the area. This does not help the reader to compare the different status of snowpack.

Figure 1 and Figure 5 have been revised to add text, symbols, and better descriptions (including in the text.)

Line 119: ‘’..1/4 mile’’

Please, consider referring to the international system of units.

Text added to refer to the appropriate distance in km

Lines 129-131 ‘’.. that a snowpack ... size (fresh snow).’’ Please, add a reference.

Reference (Painter 2019) added, along with expanded text on the retrieval.

Line 149 ‘’ ND ‘’

Please, explicit the acronym.

Expanded out to read 'North Dakota'

Figures 1, 2, and 3.

Please, consider adding symbols on the figures (see the example below) or descriptions such as bottom left to help the reader to interpret these images.


Figures 2 and 3 (along with 1, 5, and 4) have been revised to add symbols and descriptions.

Line 173 and 182 ‘’ Feb’’

Please, replace Feb with February.

Abbreviations, including 'Feb', have been globally replaced with their spelled-out parts.

Figure 5.

It is not clear where the Arkansas river valley is.

Figure 5 has been revised with arrows describing the geography and the low-level clouds in question.

Figure 6

Please, check the title and unit of y axis because they are not clear. Unit in x axis is missing

At the suggestion of another reviewer, the section on third-party applications has been revised so as not to require or include the third-party figures (6-9).  We had explicit permission to reuse these workshop images, but did not have permission to revise the third-party figures.  The discussion now reflects the content of the workshop without requiring Figure 6, and it has been removed.

Lines 395-400.

Please, check and rephrase this sentence. For example, ‘’..economic activity disruption in Nepal as a function of time ..’’ is not so clear.

The text has been revised to include context (viz the disruption caused by a catastrophic earthquake in Nepal.)

Figure 9.

Please, add titles and units to x and y axis.

As with Figure 6, Figure 9 has been removed and the discussion refocused so as not to need the figure.

Line 445 ‘’ ..through the course of the at all latitudes ..‘’ This is not clear. Please, check and revise.

The text has been revised for clarity.

Again, thank you for your considered review - we feel your suggestions markedly improved the manuscript, and we appreciate the time spent with it!

Reviewer 3 Report

This paper presented a comprehensive summary of the applications of ten years of VIIRS observations in various areas such as operational forecast use and socioeconomic studies. Future utility of VIIRS and VIIRS-like platforms are also discussed. This paper is well written. I only have some minor comments.

(1) Need to provide information on the VIIRS bands used to produce the RGB imagery such as  SeaSpray RGB  (Line 167) and the Day Cloud Phase Distinction and the Nighttime Microphysics RGBs (line 193). I assume that these RGBs are using different combination of VIIRS bands.

(2) Fig. 4 : Color scale range needs to be labeled or explained in the text. Need some texts to explain white and yellow line boundaries and some general information about the text abbreviations used in the image.

(3) Fig. 6: What is unit for VIIRS radiant heat? And what does bcm stand for in the Y axis?

 

 

 

Author Response

Thank you for your careful and attentive review to our manuscript! To address your concerns:

(1) Need to provide information on the VIIRS bands used to produce the RGB imagery such as  SeaSpray RGB  (Line 167) and the Day Cloud Phase Distinction and the Nighttime Microphysics RGBs (line 193). I assume that these RGBs are using different combination of VIIRS bands.

As suggested, we have added RGB recipes with relevant VIIRS bands to SeaSpray and nighttime microphysics sections. 

(2) Fig. 4 : Color scale range needs to be labeled or explained in the text. Need some texts to explain white and yellow line boundaries and some general information about the text abbreviations used in the image.

We have updated Figure 4 with a better explanation, as requested.

(3) Fig. 6: What is unit for VIIRS radiant heat? And what does bcm stand for in the Y axis?

Per the suggestion of another reviewer, we have refocused the third-party reporting in a more general manner to not require replotting of third-party figures.  The text is more general about workshop results - as such, we have excised Figure 6 (which we had permission to reproduce, but not to alter.)

Again, thank you for your careful review of the manuscript - we appreciate the time spent with it!

Round 2

Reviewer 1 Report

Thank you to the authors for making changes to the text. I think the improved text is acceptable for publication.