Comments on the manuscript entitled “The impact of tropospheric blockings on duration of the sudden stratospheric warmings in boreal winter 2023/24” by Ekaterina Vorobeva and Yvan Orsolini, submitted to Weather Climate Dynamics.

This research utilizes the ERA5 reanalysis data and defines the Sudden Stratospheric Warming (SSW) based on the polar-region-averaged wind field. In-depth analyses are conducted on the three major SSW events identified. The authors correctly note that the first two SSW events have relatively short durations, in contrast to the last SSW event, which persists for a substantially longer period. Additionally, they draw inferences about the relationship between the three SSW events and the tropospheric blocking pattern. The overall writing of the manuscript is commendably fluent. However, before recommending this manuscript for publication, I have several concerns that require attention.

Major issues

1. The authors ascribe the rapid termination of the first SSW event to the westward-propagating Blocking High (BH) in the North Pacific (Lines 205-207). In reality, as evident from Figures 3b and 3c, the decline in V’T’ is not solely observed in the North Pacific region; rather, the changes over the Atlantic Ocean are quite conspicuous. The authors should consider the causes of this weakening in a more comprehensive fashion and quantitatively present the contribution ratios of each BH.
2. Regarding the third SSW event, the authors indicate that the circulation after the outbreak is favorable for the upward propagation of planetary waves. Nevertheless, this conclusion is merely based on the average results for the 5–8 days following the outbreak and cannot represent the situation that may endure for up to one month.

Minor issues

1. As can be seen from Figures 2 and 5, the intensities of planetary waves at 100 hPa one month after the occurrences of the second and third SSW events show minimal differences. Yet, one is a short-lived SSW event while the other is a long-lived one. What accounts for this?
2. In Figure 5, it is observable that V_a’T_c’ is negative during the weakening phase of each SSW event. The authors need to elucidate what factors give rise to this situation.
3. The rapid weakening of the upward propagation of planetary waves is a necessary condition for the short duration of the SSW. I opine that quantitatively characterizing this feature could be an important research avenue.

Comments on “The impact of tropospheric blockings on duration of the sudden stratospheric warmings in boreal winter 2023/24” by Vorobeva and Orsolini

Summary

Using the reanalysis, this study analyzed the successive SSWs in the 2023/24 winter, which has been reported in a series of recent studies (Rao et al. 2025AR; Lee et al. 2025 Weather; Lu Qian et al. 2024). Especially, the study analyzed the linear interference of climatological waves and synoptic waves in the eddy heat flux. The blocking highs are emphasized. This paper is well written and I only have several minor questions.

Specific comments

1. The decomposition of the eddy heat flux into different terms is necessary to better understand the wave driving. However, the anomalous eddy heat flux might be problematic. See the derivation below:

(v’T’)c = (v’cT’c+v’aT’c+v’cT’a+v’aT’a)c = v’cT’c+(v’aT’a)c

(v’T’)a = v’T’ - (v’T’)c = v’aT’c+v’cT’a+ [v’aT’a - (v’aT’a)c]

This paper did not consider the contribution of (v’aT’a)c for the climatological eddy heat flux, and place this term in the total nonlinear term, which might lead to wrong conclusions.

1. L22-23: This sentence is partially true for a few SSWs that the easterlies begin to appear in the upper stratosphere. I am not sure if this statement is true for other SSWs, since the wave forcing for SSWs is primarily from the troposphere and lower stratosphere. Please insert references.

1. L26-27: The SSW occurs 6-7 times every decade. Please update the SSW frequency using the modern reanalysis. Further, models also produce a frequency 6-7 every 10 years. See Rao and Garfinkel 2021 (ERL, doi: 10.1088/1748-9326/abd4fe). Baldwin et al. 2021.

1. L31: Liang et al. also discussed the global impact of the SSW using model simulations (doi: 10.1007/s00382-022-06293-2).

1. L40-41: There are too many studies emphasizing the impact of the high blocking on the SSWs. Refer to Rao et al. 2018 (doi: 10.1029/2018JD028908) if necessary.

1. L54: This SSW is reported in several recent studies that should be considered. Add Qian et al. 2024; Rao et al. 2025 (doi: 10.1016/j.atmosres.2024.107882); Lee et al. 2024 (doi: 10.1002/wea.7656).

1. L75: that clause => which …

1. L93: Here you should discuss the possible impact of the SSW definition on the conclusion. Using the polar cap U, you find three SSWs. But if you use CP SSW definition, you might only pick up two SSWs. Rao et al. 2025 use three stratospheric disturbances to call those SSWs. It is not a big problem.

1. L99: Please add sone discussion that similar figures have been shown in Lu Qian et al. 2024; Rao et al. 2025, Lee et al. 2024.

1. L110-111: Add a reference e.g., Rao et al. 2025.

1. L131-132: This sentence is true. Is the SSW persistency of easterlies also discussed for other two SSWs. Since the first two and especially the second SSW provide a precondition for the major SSW in March 2024, the precondition of the last SSW should be discussed.

1. Figure 2: 45N is still too far from the polar region. Will the conclusion change if the latitude is changed to 75N.

1. L138: What kind of forcing is persistent and what is not? Do you have any results stating?

1. L140: Please state what aspects are consistent and what are not.

1. L168: Not sure if it is true. Might also indicate that the upward propagation of waves are weakened.

1. L187: Eq. 1 is right but the anomalous eddy heat flux definition might be problematic.

1. L196: Please clarify where the trough is situated.

1. Figure 3: The climatological waves shown in black contours are not very consistent in g-i. Please check if an error exists in the plotting script. The high over 0E is not consistent, for example. The anomalous eddy heat flux is not right as I say above.

1. L208: Where are those blockings?

1. L211: Far East? DO you mean East Asian trough?

1. L222, 226: The Alaskan blocking is not persistent at all. It weakened during the second period and reformed during the third period.

1. L236, Figure 4: Figure 4 is too noisy and boring. I am not sure if there is necessity of showing figure 4.

1. Figure 5: You did not remove the contribution from the climatology of nonlinear term. Please test if this will affect the conclusion.

1. L262: Also see Chwat et al. 2022 doi: 10.1029/2022JD037521. All the external forcings are discussed in Chwat et al. 2022 and Rao et al. 2019.

1. L273: See Rao et al. 2025AR for a review on the favorable conditions for past SSWs in last decades.

1. L301: If necessary, please add the funding information. Further, the dataset availability should be shown with feasible hyperlink address.