This is my second review of Peng Xian et al.: Arctic spring and summertime aerosol optical depth baseline from long-term observations and model reanalyses.
The authors have followed my suggestion to split their work in two papers, which somewhat helps with taking in all the provided information. However, they have dismissed most of my other suggestions without providing convincing rebuttals. Therefore, I am sorry for having to repeat much of my earlier criticism. I have worked through both versions and it took me considerable time to do so. My suggestions are therefore focussed on distilling the provided information down to what is essential and to make it easier for potential readers to take it in. I start with general comments that apply to both papers before providing specific comments for the individual parts.
General comments
The authors should make a serious effort in improving the quality of their writing. The current version of the papers does not make for enjoyable reading.
• There a plenty of statements that span over 4, 5 or even 6 lines and are very hard to follow. Please carefully go through the manuscripts and shorten or split those sentences.
• The authors’ use of parentheses to specify a statement made just before is particularly annoying. Why not go with the text in the parentheses in the first place? Or make up your mind which one is the preferred phrasing. There are so many of these statements that I won’t list them. Please revise.
• The authors should properly define all the used terms in the beginning or when first used and stick to those terms rather than providing their definition whenever they are used. This occurs particularly often for the term MAM, JJA, and high or low Arctic. Please make sure that all acronyms are introduced only once in the text. No need to re-do so in the summary. The readers should also be able to remember the extend of the covered time period without repeating it at almost every instance.
• The authors give values in the text that are often put behind a ~, i.e. maximum AOD of ~1.2. Do you know the specific value or do you provide estimates? Please be specific.
• The text is very repetitive. For instance, the point that biomass-burning smoke is the dominating contributor to Arctic AOD in summer is repeated at multiple occasions. Please identify the instances where repetitive statements fit best and move them there. You can expect the reader to remember.
Please thoroughly go through both manuscripts to get rid of redundant text, figures and tables. Some examples are given in the specific comments below.
The abstracts of both papers – but particularly of the second one - are much too long. Please try to reduce to the essential findings.
Please make sure that there is a proper connection between the two parts of this study. While part 1 is referred to in part 2 there is just one mention of part 2 in the introduction to part 1. The authors are missing the opportunity to properly connect their work.
Paper 1 on climatology and trend
Major comments:
• Redundant text: lines 160-164 (this is clear), 195/196 (the general time period has already been defined), 215-217 (repeats what has been just stated), 220-224 (reference to Toth et al. 2018 is sufficient, also why consider them in the analysis when you just made the point that artificial AODs of zero are unphysical?), 246-253 (no need to discuss a parameter that has not been used in your work), 280/281 (you can assume that readers are can draw this conclusion themselves), 431-433, 917-936 (redundant or should be part of the data or methodology sections)
• I still don’t see the need to include Section 2.10 and Figure 12 in the paper. None of the other biomass-burning emission inventories is referred to in that much detail. Also, FLAMBE is used as input to NAAPS-RA and it is not clear why showing FLAMBE maps provides added information to showing findings for BB aerosols from NAAPS-RA.
• I suggest to stick with fine mode and coarse mode rather then introducing FM and CM. This would increase readability a lot. Right now, the authors switch between using fine mode, FM, an even FM mode…
• Please make sure that the description of a figure or table is confined to the figure or table caption. The main text should not be used, e.g., to describe what a line of a certain colour represents.
• I expect that most readers are interested in the general findings of the authors’ work rather than the peculiarity of individual reanalysis models. I therefore still think that the paper would be much improved if the authors were to focus on the multi reanalysis consensus (MRC) in the figures of the main text. Presenting just the plots for the MRC in Figures 2-7, 10, 11, and 13 doesn’t prevent to authors from pointing towards differences in the considered models. If the plots (2-7, 10, 11, 13) and tables (2, 3, 4) for the three individual reanalysis are moved to the supplement, they would still be accessible to readers that are particularly interested in these differences.
• Please make sure that you properly and specifically refer to figures you are discussing rather than just providing a figure number or a list of figures at the beginning of a paragraph.
• Section 5.2.1 doesn’t really provide an objective assessment of interannual variability and is largely based on referring to individual events that should be discussed in the introduction to Part 2. I suggest to omit this section.
• It is not clear to me what is shown in Figure 8 or how the plot has been compiled. Please provide a better description.
• There is no discussion of Figure 9. What about moving this figure to an earlier position after Figure 3 so that the presentation of the satellite data is all finished before moving on to the models?
Minor comments.
• Please update the reference IPCC (2013) to IPCC (2021)
• Ice nuclei are now generally referred to as ice nucleating particles (INP)
• Line 335: on the other hand requires an earlier on the one hand
• Lines 392-400 should be moved to the introduction
• Line 414: What is it, hourly or daily data?
• Lines 476-481: this should be moved to the methods section
• Caption Figure 1: Add that the size of the circles refers to the magnitude in AOD.
• Caption Figure 3: omit second sentence. This has already been stated in the Data section
• Lines 588-605: Remove reference to Figure 3 and move a generalised version of this text to Section 2
• Line 626: CALIOP has a footprint of 70 m.
• Line 630: no need to use an acronym for data assimilation. It’s used only once and I forgot what DA was supposed to stand for by the time is was used…
• Figure 4: lines 645-650 should be moved to suitable places in the text. They don’t belong into a figure caption.
• Figure 5: move the second sentence of the caption into the main text.
• It seems that Figure 7 is discussed before Figure 6. Also the discussion of Figure 7 doesn’t seem to be quite objective: no change can be extracted if the error bars were to be considered!
• Lines 868/869: not clear which figure the authors are referring to
• Line 939: what climate models? Please specify.
Part 2 on extreme events
General comments
• Please shorten the Abstract to present just the essential findings.
• Please treat part 2 as a stand-alone paper. As such, the introduction should give a short review of the findings of part 1.
• I suggest to restructure the paper to first discuss all findings from AERONET (particularly Table 2) as the observational foundation for your methodology to identify extreme AODs. This would then allow to clearly define which sites are affected by biomass-burning aerosol to which extend. Afterwards, you can move on with the comparison to the reanalysis data (Figure 1 and Table 1) and the contribution of different components (Figure 4).
• Redundant text: 95-102 (not needed and repeated later anyway), 119-121 (method section), 197-200, 425-429, 457-459 (should be clearly described in the methods section)
• Section 3.3 should be omitted. Parts of its content – when authors list earlier observations of extreme events – should be moved to the introduction. Figure 5 and the brief discussion don’t add much insight and should be removed.
Specific comments
• Line 59: Omit Arctic
• Line 82: TOA introduced twice but there’s no need to use the acronym at all
• Lines 125-135: move text to the respective subsections in the data section
• Line 153: it’s MODIS imagery
• Line 171: what’s the difference between quality controlled and quality assured?
• Figure 2: Why does the figure include data from 14 stations when only 10 are listed in Table 1? Is there any discussion of Figure 2? Also, why not just add a line with the regression parameters for all data points to Table 1 and omit this figure?
• Figure 3: The definition of pairwise (or better temporally and spatially matched) should be provided in the method section and not in a figure caption.
• Figure 6: It is not clear what is shown in the maps. Please properly describe the data treatment in the methods section.
• Figure 9: please define spread in the methods section. No stars are visible in the plot.
• Table 3: There is no need for Table 3 as it doesn’t add to what is shown in Figure 10. Also, there’s no discussion of this table except for a brief reference such as see also Table 3
• Conclusions should be renamed to Summary. Also, please don’t re-introduce all acronyms. |
