Here, the role that the atmospheric circulation probably played during extreme dust intrusions in the western Mediterranean is analysed. This work proposes interesting ideas regarding the sources of such rare dust events, however, in my opinion, there are significant problems that need to be addressed. Thus, I would recommend a major revision of the manuscript according to the following comments, which I hope the authors will find useful.

Major Comments:

Firstly, the selection of the datasets and the time periods present inconsistencies:

1. For the dust events, MERRA-2 dataset was used, while for the atmospheric circulation NCEP/NCAR was used. These two different reanalyses may exhibit such differences in their internal variability that could make the dust transport and geopotential height fields incomparable. Could you please justify why we didn’t use datasets from the same reanalysis, also considering the higher resolution of MERRA-2?
2. In addition, the analysis is limited to 2003-2022, while data are available since 1980. Please justify why you limited your analysis to such a short period.
3. Finally, the selection of “winter” in the title and in the text is quite confusing, as in some parts of the text DJFM and/or JFM and/or FM are analysed. Please reconsider a more uniform and self-explanatory presentation of the results. In addition, I would suggest removing “winter” from the title or replace it with a more adequate phrase.

Specific Comments

1. Page 4, line 8: The leeward side of the Atlas Mountains is a favourable area of cyclogenesis. I do not agree with this statement. Please clarify.
2. Page 7, line 29: Together with the above major comments, please explain why you use 1991-2020 as reference period for the circulation anomalies and not the same as dust transport. Did you consider that maybe there are differences in atmospheric circulation due to interdecadal variability?
3. Page 10, Figure 1: It would be interesting to see how dust transport (and thus dust events) are distributed in other months as well, at least during December and April; the former to complete the “winter” and the latter to see is going on during the most active month regarding Mediterranean dust events.
4. In addition, from this Figure, we can see that January does not exhibit any exceptional behaviour, while the period 2003-2005 was also quite active for February and March. Did you check what happened regarding circulation during those years? And seizing upon this, I would like to see if there were other “active” years for the entire period of MERRA-2. I am not convinced that 2020-2022 was indeed extreme.
5. Page 12, line 14: Is this correlation statistically significant?
6. Page 14, Figure 3: Again, January has just 1 event in the “extreme period” and only 2 in the whole period. March exhibits a clear extreme behaviour during the “extreme period,” and February to a lesser extent. I would suggest investigating the behaviour of dust transport in all months and I would strongly suggest investigating if there were such events over the whole 40 years period of MERRA-2. Then, you may focus on February and March only.
7. Page 15, table 2: the comparison between January 2003-2019 and January 2020-2022 is not fair, because the latter consists only of 1 event lasting 3 days, thus, giving 1 dust day per year compared to the 0.18 of the entire period.
8. Page 16, table 3: the two parts of the table compare an 18-year period with a 3-year period. Which is the statistical significance of the differences between them? Are they significant and where?
9. Page 17, Figure 4: If I understand correctly, the second line of figures gives the clustering results only for the dust days of the 2020-2022 year period. Is this number of days adequate to provide a robust clustering, mainly for the clusters 3 and 4? My impression is that the first two clusters are quite similar for both periods implying that these two weather regimes are responsible for the dust events, while the other two are spurious.
10. Page 19, line 25: The absolute anomalies of Z200 are of course larger than Z500, as Z200 gets larger and more variable values. Except you want to stress out something else, so please clarify.
11. Page 20, line 20: How do we know that they are “intense enough to generate wind speed exceeding the threshold”?
12. Page 20, lines 19-20: Isn’t it expected since January has only 1 event?
13. Page 20, line 28: Where do we see that probability of blocking doubles?
14. Page 21, Figure 6 and respective discussion: From Figure 6b, it seems that not only the blocking activity is higher than climatology, is even lower. So, how does this affect the discussion about the extreme 2020-2022 years? I see from Figure 6d, a more zonal configuration of the jet. How could this help the northward dust transfer?
15. Page 21, lines 15-16: What do you mean by the phrase: “However, the spatial pattern hinders important intra-seasonal differences”? Why is this relevant here?
16. Page 25, lines 10-13: In conjunction with the above comment, I apologize if I’m mistaken, but I don’t see an enhanced blocking and poleward jet configuration during 2020-2022, at least a more prominent one than for the entire period. So, what triggered these extreme events? I think that it would be interesting to see the synoptic configuration as well.
17. Page 27, line 10: The period 1958-1998 is totally different from the period used in the present study, thus, any trends found in the frequency of cut-off lows back then are not necessarily continue to the examined period.

Minor comments

1. Page 4, lines 12-13: A reference is needed here.
2. Page 7, line 18: “as the anomaly of the projection”. Please clarify which projection you refer to.
3. Page 7, line 19: “and all indices of that day”. Then what? The phrase is incomplete.
4. Page 12, line 18: I would say it is 1.6 dust events/year.
5. Page 19, line 21: You mean composite anomalies?
6. The literature cited in the text and in the references is poorly prepared with many mistakes and omissions making it very difficult for the reader to keep track.

Please find below a non-exhaustive list:

• Page 2, line 28: Kuula et al. 2021 wrong year?
• Page 4, Line 11: correct kikas to Gkikas
• Page 6, Line 21: Liu et al. 2009 or 2019?
• Page 12, line 11: Moulin et al. 1998 or 1997?
• Page 28, line 23; page 30, line 8; page 30, line 34; page31, line 14; page 32, line 30; page 33, line 14; page34, line 34; page 36, line 23; the paragraphs are merged.
• References Barnaba et al., Gelaro et al., Hersbach et al., Holben et al., Klose et al., Labban et al., Liu et al., Munoz et al., Ryder et al., Schepanski et al. are not cited in the manuscript.

Review_report_egusphere_2023-1749

The current study examines the meteorological drivers favored the occurrence of dust outbreaks in the western Mediterranean during winter periods over recent years (2020-2022). In winter, the occurrence of dust episodes is more common in the central/eastern Mediterranean in contrast to the western sector. The authors analyze/present a variety of reanalysis and observational datasets (observational, reanalysis) towards reaching to their goal. I have some concerns about the datasets which are utilized. Despite this, I believe that it is very interesting and constructive study, and it can be accepted for publication after revising the manuscript based on the following comments/suggestions:

1. Page 6 – Line 12: Why are you using the MODIS Collection 6 data and not those of 6.1?
2. Page 6 (Line 24) – Page 7 (Line 5): It would be useful here to elaborate how much your results are affected by “mixing” two different CALIPSO versions. I would remove Level 2.5km from the text because it is confusing (Level 2 – 5 km resolution along the satellite track).
3. Section 2.2: Can you explain why you are not using a more updated reanalysis dataset providing numerical products at finer spatial resolution (e.g., ERA5, GDAS)? I think that this is a very important issue since atmospheric patterns (not evident in the coarse NCEP/NCAR reanalysis dataset) can be revealed.
4. Page 7 – Lines 18-19: Can you rephrase this sentence? It is not so clear.    
5. Page 8 – Lines 11-12: Do you mean the low-level jet or there is mistake in the pressure levels?
6. Page 12 – Lines 1-16: The authors state that they are processing the MODIS L3 AOD data. Which data are used exactly (daily or monthly)? Can you comment (show) how cloud contamination can “impact” your results considering that the analysis is representative for winter months? Have you checked the temporal availability of the MODIS data? I assume that due to extended cloud coverage there will be gaps throughout the study period. If so, this might have impact on the calculation of the mean and standard deviation values.
7. Page 13 – Lines 4-17: It would be useful to discuss further the maximum occurrences recorded in February 2016 and 2017. How much different was the atmospheric circulation in the aforementioned months? Are they other factors which can explain these maximum frequencies?
8. Page 16 – Lines 13-14: How much different are the atmospheric patterns presented here with those discussed in previous relevant studies?
9. Page 16 – Lines 14-17: I would propose to rephrase these sentences to be consistent with the relevant figures. What do you mean four concatenated cut-off lows? How are you excluding the possibility of a persistent low-pressure system? I would suggest discussing more the position and the strength of the anticyclones as well as the convergence zones.
10. Page 17 – Lines 4-5: Can you please rephrase this sentence?
11. Figure 4: It seems that between the clusters 1 and 2 many similarities in spatial terms exist and there are deviations on the relative frequencies. Nevertheless, this is not the case for the clusters 3 and 4, as already stated in the manuscript. Can you please interpret the observed inconsistencies?
12. Figure 5 and the relevant discussion: The authors state that “…that some WRs do not have a direct apparent correspondence with the clusters of Figure 4 (e.g., GL, ZO).”. I am confused with this part of the study. How much can affect this inconsistency the connection between the patterns that you have obtained from the cluster analysis and the weather regimes of Grams et al. (2017)? If I am not missing something, in the latter study it is not considered the dust transport from N. Africa towards the region of interest.
13. Page 20 – Lines 1-4: It would be easy to reproduce the maps with winds at 10 meters in order to check in which regions the wind speeds exceed the thresholds.
14. Page 20 – Lines 6-7: I would remove or rephrase the ‘…before being absorbed by the general circulation.’
15. Section 4: Please consider splitting this section in “Discussion” and “Conclusions”. Also, I believe that the part of the text after the bullets can be reduced by summarizing the main findings and outcomes.