Articles | Volume 22, issue 6
© Author(s) 2022. This work is distributed underthe Creative Commons Attribution 4.0 License.
Evolution of the intensity and duration of the Southern Hemisphere stratospheric polar vortex edge for the period 1979–2020
- Final revised paper (published on 31 Mar 2022)
- Preprint (discussion started on 10 Sep 2021)
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor |
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RC1: 'Comment on acp-2021-676', Anonymous Referee #1, 08 Oct 2021
- AC1: 'Reply on RC1', Audrey Lecouffe, 26 Jan 2022
RC2: 'major revisions required', Anonymous Referee #2, 20 Oct 2021
- AC2: 'Reply on RC2', Audrey Lecouffe, 26 Jan 2022
Peer review completion
AR: Author's response | RR: Referee report | ED: Editor decision
AR by Audrey Lecouffe on behalf of the Authors (26 Jan 2022)  Author's response Author's tracked changes Manuscript
ED: Referee Nomination & Report Request started (12 Feb 2022) by Peter Haynes
RR by Anonymous Referee #1 (15 Feb 2022)
ED: Publish subject to technical corrections (21 Feb 2022) by Peter Haynes
Comments on “Evolution of the stratospheric polar vortex edge intensity and duration in the Southern hemisphere over the 1979 – 2020 period” by Lecouffe et al. (2021)
Using the ERA-Interim reanalysis, ENSO index, QBO observations, and solar cycle index, Lecouffe et al. calculated the metrics of the southern hemispheric stratospheric polar vortex at 50 hPa using the vortex elliptical diagnostics. The variable PV is used in the study due to its conservation property on the isentropic surface in the free atmosphere. The paper is interesting and provide some useful information to the community. However, I also found some minor shortcomings in the paper. The authors might need to well review the most recent publications in the literature, and build their work on the existing results in literature. For example, previous studies have confirmed that the ENSO does not have significant impact on the Southern Hemisphere polar vortex. But this paper still discusses the weak impact of the ENSO on the vortex edge. Due to those problems in the manuscript, I suggest a substantial revision before the paper could be published.
The impact of ENSO, solar cycle, and QBO on the polar vortex in both hemispheres has been widely and exhaustively studied in literature. However, this manuscript fails to provide a sufficient review on the most recent publications. The impact of the canonical ENSO on the SH polar vortex is insignificant in both observations and modeling studies (Rao and Ren 2020 https://doi.org/10.1007/s00382-019-05111-6; Hurwitz et al. 2011 https://journals.ametsoc.org/view/journals/atsc/68/4/2011jas3606.1.xml). The impact of QBO on the stratosphere is also reported in the latest literature (Rao et al. 2020 https://doi.org/10.1175/JCLI-D-19-0663.1; Butchart et al. 2019 https://doi.org/10.5194/gmd-11-1009-2018). As the solar cycle’s impact on the SH stratospheric polar vortex, it is also discussed most recently in Figure 3 of Rao et al. 2020JGR (https://doi.org/10.1029/2020JD032723). I suggest the authors to explore more of recent publications to see what has been done and what has not.
Ample evidence has reported the similarity of the 2002 and 2019 SSWs in the SH. The paper discusses the main characteristics of the polar vortex edge in 2002 but fails to mention the 2019 SSW. Related studies are also ignored in the paper. The main characteristics of the SH polar vortex during the 2019 SSW have also been reported in Rao et al. 2020JGR (https://doi.org/10.1029/2020JD032723), Shen et al. 2020GRL (https://doi.org/10.1029/2020GL089343). The background of this study is still lacking and the references can be further improved.
In my understanding, the start date of the stratospheric polar vortex in both hemispheres are mainly forced radiatively due to the annual cycle, and it should be very stable. I checked the start date of the polar vortex in the NH using the zonal mean zonal wind at 60N and 10hPa as the threshold. I found that the start date of the NH polar vortex is very stable. In contrast, the final warming date in both hemispheres differs from year to year due to the dynamics associated with planetary wave activities. However, this study shows that both the start date and end date of the SH polar vortex have a large interannual variability. What forces such a strong variation of the start date of the stratospheric polar vortex. The authors also failed to mention the most recent studies on the final warming date in the SH (Rao and Garfinkel 2021CD, https://doi.org/10.1007/s00382-021-05647-6). They also discussed the possible impact of the ozone depletion and recovery on the polar vortex final warming date.
https://agupubs.onlinelibrary.wiley.com/doi/toc/10.1002/(ISSN)1944-8007.ARCTICSPV. Choose several references and discuss the ozone depletion in the NH (e.g., Garfinkel 2020, 2021; Feng et al. 2021). The authors really should read more to enrich the introduction of the paper. This version is really not satisfactory.