Intraseasonal to interannual variability of Kelvin wave momentum fluxes as derived from high-resolution radiosonde data

Sjoberg, Jeremiah P.; Birner, Thomas; Johnson, Richard H.

doi:https://doi.org/10.5194/acp-17-8971-2017

Articles | Volume 17, issue 14

https://doi.org/10.5194/acp-17-8971-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-17-8971-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 17, issue 14

Research article

|

26 Jul 2017

Research article |

| 26 Jul 2017

Intraseasonal to interannual variability of Kelvin wave momentum fluxes as derived from high-resolution radiosonde data

Jeremiah P. Sjoberg, Thomas Birner, and Richard H. Johnson

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Final revised paper (published on 26 Jul 2017)
Supplement to the final revised paper
Preprint (discussion started on 13 Jan 2017)
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Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Please see the attached PDF file', Anonymous Referee #3, 16 Jan 2017
- AC1: 'Author responses to reviewers', Jeremiah Sjoberg, 16 May 2017
RC2: 'Referee comments', Anonymous Referee #1, 11 Feb 2017
- AC2: 'Author responses to reviewers', Jeremiah Sjoberg, 16 May 2017

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Jeremiah Sjoberg on behalf of the Authors (17 May 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (18 May 2017) by Martin Dameris

RR by Anonymous Referee #1 (30 May 2017)

Suggestions for revision or reasons for rejection

I think that the authors have thoroughly made the responses to my comments and that the revised manuscript is improved. I am happy that one of my suggestions was useful in their method, allowing for estimation of the flux for more easterly QBO cases. Although I have a few other comments the authors may consider, these may not lead to a significant change in the manuscript: minor comments. I recommend this paper for publication, after the authors consider the following comments, but with no requirement of further review by me.

[ minor comments ]

P6 L14: You may not require here the zonal phase speed to be positive. It has been already guaranteed in Eq. (3) with the positive and negative signs of k and m, respectively, resulting in the positive intrinsic frequency and thus positive intrinsic phase speed.
Please remove this sentence or place it around P5 L5, providing why the m is defined as negative.

(If the authors follow the above comment)
P6 L16–18: “Anywhere the above constraints are ...” : If the constraint for the positive intrinsic phase speed would not actually constrain the estimation (see the above comment), now it seems that you have only one constraint: Lx > 500 km.
If so, the sentences in this paragraph could follow the last sentences in the previous paragraph (“ … 500 km.”), after slight modification of the sentence in L16.

P10 L7: I think that “is westerly. In easterlies” should be changed to “is westerly or strong easterly (|u| > N/|m|). In weak easterlies (|u| < N/|m|)”, given that M ~ k/|m| ~ omega / ( U|m| + N ). Also, I do not understand the last two sentences in this paragraph (“i.e., a given ...”). Regarding the former sentence of the two, do you mean that “The increase by the overestimation of vertical wavelength in westerly and strong easterly dominates over the decrease by that in weak easterly” ?

P14 L20: “Our results may then give an upper estimate of the flux amplitude.”: maybe true at the altitudes relatively close to the tropospheric source. Around z = 23 ~ 25 km, the amplitude maxima could possibly propagate away to the east of these sites (i.e., on the Pacific ocean).

P21 L10: “even if the whole of the Tropics is considered for determination of events” : Did the “all points between 10S-10N” mentioned in P18 L22 mean the whole longitudes ? Not the 30 degree longitude width in 10S-10N ?
Anyway, I think the composite analysis with the cases of convections west of the observation site and that with the convection cases in whole tropics are totally different approaches, regardless of the qualitatively similar results from them.
In the latter analysis, the captured events may represent strong convection cases not only at the upstream but also downstream of the observation site.
It may be not an expected result that the feature in Fig. 10 -- re. strong/weak MJO -- qualitatively holds also for the latter analysis, especially at the lowermost altitudes (z ~ 18 km) close to the convections.

[ technical corrections ]

P3 L12: “positive contribution”: Please rephrase this.

P4 L17: Please change “for changes” to “for moderate changes”. Otherwise, this sentence conflicts with the next sentence.

P5 L13: Please delete either of “reach or” or “or extend beyond”, as the two have the same meaning here.

P6 L7: I would suggest changing “For positive omega and sufficiently strong easterlies,” to “For sufficiently strong easterlies, if omega is set to positive,”

Figure 1b: The sign of zonal wind perturbations (contour) is not distinguishable, although one can find it from Fig. 1a. Please add at least one contour for each sign in Fig. 1b.

Figure 2a: The standard error should be defined in the figure caption.

P10 L6: “verifies”

P16 L10: “the annual mean climatology displays descending signals of the flux and of easterlies during this span”: Is this result previously mentioned with Fig. 6 ? If not, please include it there.

P18 L5: include a comma before “making”.

P18 L12: Please delete “simply”.

P21 L4–5: Please rewrite this sentence.

P21 L9: “incipient”

P21 L16: “showed” ; “discernible”

P22 L11: Now Fig. 6 has been changed from that in the original manuscript. Please change “westerly” to “mainly westerly below z ~ 21 km”.

P22 L26: Please delete “an annual periodicity with”.

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ED: Reconsider after minor revisions (Editor review) (01 Jun 2017) by Martin Dameris

AR by Jeremiah Sjoberg on behalf of the Authors (05 Jun 2017) Author's response Manuscript

ED: Publish as is (16 Jun 2017) by Martin Dameris

AR by Jeremiah Sjoberg on behalf of the Authors (22 Jun 2017)

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Short summary

Observational estimates of tropical, large-scale fluxes of zonal momentum from troposphere to stratosphere remain challenging. We present an extended technique for estimating the daily amplitudes of these fluxes using data captured from balloon-borne radiosondes. Climatological analysis of our time series matches expectations of annual and interannual variability, indicating reliability in our estimates. Vertical resolution less than 1 km is found to be important for precise estimation.