see pdf

Publisher’s note: this comment is a copy of RC1 and its content was therefore removed.

I enjoyed reading through this review. I really appreciate all of the work done by the authors to bring all of this information together and organize it in a coherent manner. 

I was ask by Dr. Harnik to focus my review on Section 5. So that is what I have done. 

All of my comments are minor comments. I have some additional papers that you might consider citing. I have listed them all at the end to make things more organized.

Line 1522: You mention an early reanalysis product produced by NASA for 1985– 1989, and then reference Schultz and Mass, 1993. Are you sure that is the reference you want there?

Lines 1525 – 1533: I agree with you about the utility of reanalyses products, but they also have potential biases, especially in moisture processes. This seems like a good place to mention this. I believe that most of the results discussed in this review that utilize reanalysis are valid – or at least qualitatively correct at the synoptic scale. However, I also think the biases in precipitation rates and clouds in reanalyses give a reason to keep some open mind to the possibility that the reanalyses do not provide a complete and perfect picture of the physics. 

Naud, C.M., J. Jeyaratnam, J.F. Booth, M. Zhao, and A. Gettelman, 2020: Evaluation of Modeled Precipitation in Oceanic Extratropical Cyclones Using IMERG. J. Climate,33, 95–113, https://doi.org/10.1175/JCLI-D-19-0369.1 

McErlich, C.,  McDonald, A.,  Renwick, J., &  Schuddeboom, A. (2023).  An assessment of Southern Hemisphere extratropical cyclones in ERA5 using WindSat. Journal of Geophysical Research: Atmospheres,  128, e2023JD038554. https://doi.org/10.1029/2023JD038554

Line 1575: I suggest adding a sentence or two regarding the fact that the relationship between the precipitation and cyclone intensity is also subject to details about the upper-level forcing and the latitude of the cyclone. Two papers that might be relevant here: 

Booth, J. F., Naud, C. M., & J. Jeyaratnam, 2018: Extratropical cyclone precipitation life cycles: A satellite-based analysis. Geophysical Research Letters, 45, 8647-8654. https://doi.org/10.1029/2018GL078977

Sinclair, V. A., and J. L. Catto, 2023: The relationship between extra-tropical cyclone intensity and precipitation in idealised current and future climates, - Weather and Climate Dynamics.

Line 1617: Section 5.2.

Let me start by saying that I think this review article is already 100% sufficient. It is quite long as well. So, I am giving the following recommendation with caution. I will agree with the authors if they choose to ignore this suggestion. I wonder if you might consider adding a subsection in 5.2 on more recent work on energy fluxes from the surface and their role in the diabatic forcing of ETCs. The most recent work that I know of on the topic is this one: 

Demirdjian, R., J. D. Doyle, P. M. Finocchio, and C. A. Reynolds, 2023: Preconditioning and Intensification of Upstream Extratropical Cyclones through Surface Fluxes. J. Atmos. Sci.,  80, 1499–1517,  https://doi.org/10.1175/JAS-D-22-0251.1.

Within that work, the authors will see that there have been other relatively recent works focused on low-level diabatic heating and the associated surface fluxes. As I said though, I would be completely fine if the authors decided that this work is outside of the scope of their review.

Line 2810 or elsewhere in Section 5.6.3: You should consider referring to Hawcroft et al. 2017.

Hawcroft, M. K., H. Dacre, R. Forbes, K. Hodges, L. Shaffrey, and T. Stein, 2017: Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model. Climate Dyn., 48, 2255–2278, https://doi.org/ 10.1007/s00382-016-3204-6. 

Review of “The importance of diabatic processes for the dynamics of synoptic-scale extratropical weather systems-a review (Sections 1-4, 6)”

Authors: Heini Wernli and Suzanne L. Gray

General comments:

This article reviews the historical progress and current understanding for the effect of diabatic heating on the extratropical weather systems. In the section 2, several kinds of theoretical framework to understand the effect of diabatic are described. Historical overview from 19^th century for the studies for the impact of diabatic heating on the intensification of cyclones is described in the section 3. Then, the detailed results of studies for the diabatic effects on cyclones are reviewed in section 4. I really enjoyed reading the article, and I believe that this article is highly valuable for readers to know the historical overview and current understanding for the diabatic effects in extratropical weather systems. Overall, the article is well structured and is easy to read. Thus, I recommend that this article can be published, although I have just several recommendations to add references for the statistical study of cyclones in the Pacific.

Specific comments:

1. The descriptions for explosively developing cyclones in Pacific is relatively low compared with those in Atlantic. More descriptions and references may be added in the section 4.1.4.

e.g.,

Yoshida, A., and Y. Asuma, 2004: Structures and environment of explosively developing extratropical cyclones in the northwestern Pacific region. Mon. Wea. Rev., 132, 1121–1142. https://doi.org/10.1175/1520-0493(2004)132<1121:SAEOED>2.0.CO;2

Zhang, S., G. Fu, C., Lu, and J., Liu, 2017: Characteristics of Explosive Cyclones over the Northern Pacific, J. Appl. Meteor. and Clim., 56(12), 3187-3210. https://doi.org/10.1175/JAMC-D-16-0330.1

1. The adding of descriptions for recent studies for the effects of SST front and associated surface fluxes on the structures and dynamics of extratropical cyclones would be useful for readers if it is possible.

e.g.,

Bui, H., & Spengler, T. (2021). On the influence of sea surface temperature distributions on the development of extratropical cyclones. Journal of the Atmospheric Sciences, 78(4), 1173-1188.

Demirdjian, R., Doyle, J. D., Finocchio, P. M., & Reynolds, C. A. (2022). On the influence of surface latent heat fluxes on idealized extratropical cyclones. Journal of the Atmospheric Sciences, 79(9), 2229-2242.

Hirata, H., Kawamura, R., Kato, M., & Shinoda, T. (2015). Influential role of moisture supply from the Kuroshio/Kuroshio Extension in the rapid development of an extratropical cyclone. Monthly Weather Review, 143(10), 4126-4144.

Reeder, M. J., Spengler, T., & Spensberger, C. (2021). The effect of sea surface temperature fronts on atmospheric frontogenesis. Journal of the Atmospheric Sciences, 78(6), 1753-1771.

Tochimoto, E., & Niino, H. (2022). Comparing frontal structures of extratropical cyclones in the northwestern Pacific and northwestern Atlantic storm tracks. Monthly Weather Review, 150(2), 369-392.

Tsopouridis, L., Spensberger, C., Spengler, T., 2021a: Characteristics of cyclones following different pathways in the Gulf Stream region. Quart. J. Roy. Meteor. Soc., 147, 392–407. https://doi.org/10.1002/qj.3924

——, Spensberger, C., Spengler, T., 2021b: Cyclone intensification in the Kuroshio region and its relation to the sea surface temperature front and upper‐level forcing. Quart. J. Roy. Meteor. Soc., 147, 485–500. https://doi.org/10.1002/qj.3929

See uploaded pdf.

This very comprehensive review on the topic of diabatic processes in synoptic extratropical weather systems will become the definitive guide for researchers in this field. The review covers the history of the development of the topic over the past century. I was tasked with reviewing the introduction and the second half of the manuscript, which is concerned mostly with developments over the past 20 or so years.

I particularly like the schematic diagram showing the structure of the manuscript and where different weather systems and phenomena can be found. This will be very helpful for readers who wish to dip in and out of the manuscript to navigate the huge wealth of information.

The structure of the second half of the paper (section 5) is logical and easy to follow, covering different categories of extratropical cyclones, diagnostics and methods of analysing diabatic processes, features ranging from waveguides down to the mesoscale, and finally field experiments and climate change. The figures included are very nicely chosen to illustrate the key concepts explored.

Another aspect of the paper that I particularly like is the inclusion of details on the contributions from women that have increased in the past 20 or so years. It is heartening to see both the improvement in gender equality in this research area, and also the acknowledgement that there was an improvement to be made in the first place.

Given the comprehensive nature of the review, and the present quality of the writing, it is difficult to find much to add. So, I only have a few minor comments and suggestions.

1. Line 1496: “Millennia” -> “millennium”.
2. There are a number of uses of American English (where I think the majority of the text is written in British English). I will point out a few of these.
   1. Line 1508: “generalizing”.
   2. Line 1631: “categorization”.
   3. Line 2236: “discretization”.
   4. Line 2322: “visualize”.
   5. Line 2506: “realizing”.
   6. Page 96: “summarize”.
3. Line 1592: “southern hemisphere” -> “Southern Hemisphere”.
4. Line 1792: “northern hemisphere” -> “Northern Hemisphere”.
5. Line 1796: as points 3 and 4.
6. Line 1899: I don’t think it is obvious what “low frequency jet” means.
7. Line 1983: Perhaps the word “intensifies” is ambiguous here.
8. Line 2079: Perhaps the reference for the impermeability theorem could be added here also.
9. Line 2229: “which is defined as events”, I think should be “which are defined as events”.
10. Line 2414: Here I noticed an inconsistency in the spelling of parameterisation/parameterization.
11. Line 2661: It would be helpful to reference the section here with the equation.
12. Line 3112: Suggest also citing Martius et al 2016 and Owen et al 2021.

References:

Martius O., Pfahl S., Chevalier C. (2016) A global quantification of compound precipitation and wind extremes, Geophys. Res. Lett., 43 (14), pp. 7709-7717.

Owen LE, Catto JL, Stephenson DB, Dunstone NJ. (2021) Compound precipitation and wind extremes over Europe and their relationship to extratropical cyclones, Weather and Climate Extremes, volume 33, DOI:10.1016/j.wace.2021.100342.