Review of the manuscript entitled “The intrinsic relationship between cyclones, anticyclones, and Rossby Wave Breakings in the North-Atlantic” by Tamarin-Brodsky and Harnik

It is a well-written and interesting paper that contributes to the knowledge on Rossby wave breaking and their link with cyclones and anticyclones. The methodology is appropriate. I only have relatively minor remarks and technicalities that need to be addressed before publication. They are listed below following the order of the manuscript.

Main body of the manuscript:

Line 67: In order to relate to the expressions given later in the same paragraph, maybe add (u’v’) after “eddy momentum fluxes”.

Line 71: Please state that q is here the relative vorticity (and not the potential or absolute vorticity).

Lines 142-143: Cyclones correspond to positive values of relative vorticity and anticyclones to negative values. Therefore, maxima in relative vorticity correspond to cyclones and minima to anticyclones. However, the threshold given here (10-5 s-1) is positive. Is it an absolute value of relative vorticity? The same comment applies for Fig. 3. The intensity represented with the colors and threshold given in the caption are always positive even for the anticyclones (panels b and d). Also, write somewhere that the intensity of the cyclones and anticyclones is given by the relative vorticity at 850 hPa at the cyclone centre location (and not an average or maximum value in an area around the cyclone).

Line 155: Can the authors justify the use of the 350 K isentrope for detecting the RWB? Previous studies have used several isentropes to make sure that they cover the tropopause at all mid-latitudes (see for example Fig. 2a in Martius et al. (2007) (https://doi.org/10.1175/JAS3977.1) for the location of the tropopause relative to the isentropes). One can expect more (less) frequent AWB (CWB) at 350 K than at a lower isentrope. As the actual frequencies of AWB and CWB are not given in Fig. 1, it is difficult to get an idea of the relative frequency of the two wave breaking types.

Line 166: How do the authors define “maximum overturning”? Please precise.

Lines 166-168: How do the authors choose these three threshold values? Are they taken from a previous study?

Lines 180, 227: I believe that “recovers” is not the right word in this context. I suggest to change this word's occurrences with “in agreement with” or “in accordance with” previous studies or a particular study. In lines 180-181, I suggest to cite Strong and Magnusdottir (2008) for example and maybe other studies.

Line 252: ”anticyclone locations are mostly below the upper-level ridge”. The meaning is not clear. I suggest to replace “below” with within.

Lines 263-268: Only the cyclones positions are discussed. The anticyclones positions need to be discussed in this paragraph as well.

Line 268: “maximum” -> most frequent.

Line 283: Are the displacement values significantly different? Could the authors provide a standard deviation?

Lines 284-285: I do not find the statement about the anticyclones being located at higher latitudes convincing. First, because a reference position is needed: higher than what, than anticyclones positions during AWB or cyclones positions during CWB? Second, because apart form the local maximum over Greenland, the rest seems to be at lower latitudes than the cyclones during CWB and anticyclones during AWB. Moreover, the reference of Fig. 4 is missing to understand the full sentence.  

Lines 303-305: This sentence is not very understandable to me and needs to be adjusted. Does the “in the next section” refer to section 5? It is not clear.

Line 335: “The negative upper-level meridional velocity … is mainly due to the intensifying anomalous ridge-trough system”. How can the authors know that the southward meridional wind is due to the amplifying ridge-trough and not the cause for the amplification of the ridge and trough?

Line 340: It is not clear to me where the “background anticyclonic shear” is visible. Could the author precise it? Isn’t there also cyclonic shear on the southern side of the anticyclone?

Line 418: “an upper-level breaking in the corresponding sense is often found at upper-levels (Fig. S4 and Fig. S5)”. To me, it is not clear from these two figures that there are any wave breaking  happening. Therefore, I suggest to add the wave breaking frequency (as a percentage of the number of events considered in the composite and not normalised, see my previous comment above).

Section 5: Could the authors also display T = 1 and T = 2 days on Fig. 9? It would help to see even more clearly how different these “anomalous life-cycles” are from the regular life cycles displayed in Figs. S4 and S5, which display T = -2 to T = 2 days.

Lines 482 and 485: “while anticyclones are found to the NE of the cyclones” and “generally to the NE of the cyclones” seem to have the same meaning and the second occurrence to be an unnecessary repetition of the first. I suggest to remove the second occurrence.

Typos and others:

Title: North-Atlantic -> North Atlantic

Line 37: (CWB),(e.g. Fig.1b) -> (CWB) (e.g. Fig. 1b)

Line 60: Section 22.2 -> Section 2.2

Line 129: Conclusion -> Conclusions

Line 135: December-January -> December-January-February

Lines 132-133: velocities -> wind

Line 142: 850 hPa vorticity -> 850 hPa relative vorticity

Line 143: centeres -> centers (US spelling) (or centres UK). “centers” is used on line 147.

Line 143: 1.10-5 -> 10-5. The 1 does not seem useful.

Line 176: centeroid -> centroid

Line 178: braking -> breaking

Line 198: Full stop missing at the end of the sentence.

Line 199: storm-ceneterd -> storm-centered

Lines 216, 223: show -> shows

Line 223: a low-PV… a high-PV -> a low-PV tongue … a high-PV tongue

Line 225: deccelerate -> decelerate

Line 226: composite -> composites

Lines 260, 262, 263, 264, 267: “??” The references to Fig. 4 did not appear well.

Lines 261-262: magnitudes -> intensities

Line 9 and throughout the manuscript: I do not think it is correct to “centre around”. I would rather say “centre on” the (anti)cyclone location.

Line 303: subsection -> subsections

Lines 343-344: Tamarin and Kaspi, 2016 -> Tamarin and Kaspi (2016)

Line 368: anticycloniclly -> anticyclonically

Line 402: Fixing -> Adjusting

Line 406: jet is remains -> jet remains

Line 411: it east -> its east

Line 415: In section (4a) and (4b) -> In sections 4.1 and 4.2

Line 460: Fig. ??a. The reference to the figure (Fig. 4?) did not work.

Line 520: seem -> seems

References: Almost all capital letters are missing in the titles of the referenced articles, the journal names should be abbreviated and the doi provided (see https://www.weather-climate-dynamics.net/submission.html#references). For example, in the first reference of Benedict et al., north atlantic should be North Atlantic, Journal of the Atmospheric Sciences should be abbreviated, and the doi provided. The issue number is not necessary (for example in Eady 1949).

Figure 4: In the sentence before the last: denote -> denotes

Figure S8: “after to” -> after

Overall, I suggest to replace “velocity” with air velocity, wind, or wind speed.

Figures: 

Several figures display PV at 250 hPa whereas, RWB events are detected in PV fields on the 350-K isentrope (line 155). Although the authors wrote that the results are similar when detecting RWB in PV at 250 hPa and use the wind at 250 hPa, I still find it inconsistent to display PV at 250 hPa and not at 350 K since it is the field used to detect RWB.

About the cyclone-centred figures: it looks like a “random” PV isoline is plotted. I assume that the contour value has to be changed to illustrate the authors’ point, but the reason for using different contours on different figures could be stated. Also, as an example why choosing the 3.2 PVU contour in Fig. 6? Was the 3 PVU contour not good enough?

Figure 1: I understand why the authors are representing the wave breaking frequencies with normalised pdfs, but information about the relative (and actual) frequency of the two types is lost, isn’t it? Or do AWB and CWB have the same frequency? The year of the two particular events (panels a and b) is not given in the caption. Please add it and maybe save space by shortening the dates such as, e.g., 7 Dec YEAR 00UTC. Finally, I suggest to increase the size of the domain to the east, such as to be more consistent with the domain mentioned in line 171, that extends to 20ºE (starting the figure at 260ºE is fine). It would also be great if the longitude values in the x-axis could correspond to the values in the text (expressed with ºW), that is instead of “270, 300, 330, 360”, -90, -60 -30 and 0 could be used.

Figure 2c: How do the authors explain that the low-PV streamer is not as distinct as for the AWB composite? A blue tongue is not present.

Figure 3: See my comment above about the intensity of anticyclones. Anticyclones should have negative relative vorticity but the colorbar shows positive values for both cyclones and anticyclones. Could the author mention that the absolute relative vorticity is used (if that is indeed the case)? Also, why is the PV contour not the same as in Fig. 2? Aren’t they composites over the same wave breaking events?

Figure 5: It would be great to have x-axis labels. Moreover, the name of the second row needs to be changed: Antiyclones -> Anticyclones

Figure 7: The letters designating the panels a, b, and d are not well aligned. I would remove the Ucross as x-axis label and replace them with the columns title. I would change “U250 tav” to U250 with a bar over U to be consistent with the notation in the text (line 329). If the authors make this change, they can also change “U250 total” to U250. The red and pink lines are not very well distinguishable. A lighter pink would be maybe better.

Figure 8: “Same as Fig. 4”. Isn’t this figure the same as Fig. 6?

Figure 9: On the top label of the middle figure it should be T=-1 and not T=1. 

Units in captions and text:

- the authors often use ms-1 as unit for wind. I personally find this writing misleading as it can refer to millisecond and not meters per second. Therefore, I suggest to add a white space in between the m and the s: m s^-1.

- the authors use both mb and hPa as unit for pressure. Choose one and keep it all along the manuscript.

Supplement: 

Figure S2: It is similar to Fig. 4 of the manuscript and not to Fig. 3.

Figure S3: The same colormap as Fig. 1c,d could be used for an easier comparison.

Figures S4, S5 a,f: Do these figures actually show T=-2 days and not T=-3 days? In the manuscript T=-3 days is used. Moreover, please state that the PV anomalies are the contours (top row), the zonal wind at 250 hPa the shading and the SLP anomaly the contours (bottom row).

Figure S5: This figure is the same as Fig. S4 and not S1.

Figures S6 and S7: The title of panel a shows T=-3, but the caption says T=-2 days. Please correct.

Figure S7: This figure is the same as Fig. S6 and not S3.

This manuscript presents a detailed analysis of the relationship between RWB and low-level weather systems over the N Atlantic. It is well written with very clear figures, and will be acceptable with only minor revisions. My main concern is that it is not clear what the new results are (relative existing literature) and, more importantly, what questions are being (or could be) solved with this analysis.  I think there needs to be better justification for the analysis, comparison with previous studies (to highlight new aspects), and discussion of implications of the results. 

Specific Comments

Title: I think “low-level” should be included in the title, Maybe “… relationship between Rossby Wave breaking and low-level weather systems”?

Abstract: There is no discussion of implications of the results in the abstract , and after reading both I was left with a “so what?” feeling. I think this needs to end with discussion of implications.

Conclusions:  

Figure 10 should be referred to in bullets (1) and (2), or introduced in the sentence before the bullets.

Bullets (5) and (6) seem of different flavor to (1)-(4), and I wonder if better as discussion paragraphs.

My comment on the abstract applies for the conclusions as well.