the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
On the Quasi-2-Day Planetary Waves in the Middle Atmosphere During Different QBO Phases
Sheng-Yang Gu
Shu-Yue Zhao
Dong Wang
Abstract. We found that the interannual difference of the W3 and W4 Q2DW is significantly correlated with the Quasi-Biennial Oscillation westerly (QBOW) and easterly (QBOE) phase, identified from the analysis of the 2003 to 2020 MERRA-2 and SABER atmospheric data. The amplitude of the zonal wind in the QBOE phase is approximately ∼10 m/s stronger than that in the QBOW phase. Mean zonal easterly winds are stronger in the QBOE phase than in the QBOW phase, while westerly winds are stronger in the QBOW phase. The Q2DW is present in the summer, and the background wind is easterly in both hemispheres. The mean temperature amplitudes of W3 and W4 in the QBOW phase are stronger than those in the QBOE phase, and the difference is ~2 K and ~3 K (in the Southern Hemisphere); ~2 K and ~3 K (in the Northern Hemisphere), respectively. The mean wave period of W4 in the QBOW phase in the Northern Hemisphere is shorter than that in the QBOE phase. The W3 mode is modulated by atmospheric eigenmodes in both hemispheres and shows slight differences in the QBOW and QBOE phases, while the W4 mode is more likely to show significant differences in the different QBO phases. Our diagnostic analysis suggests that the amplification of the QBOW phases W3 and W4 may be due to stronger mean-flow instabilities and background winds in the mesosphere. In addition, planetary waves gain stronger source activity during the QBOW phase to provide sufficient energy for propagation and amplification.
Liang Tang et al.
Status: final response (author comments only)
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CC1: 'Comment on acp-2022-778', Fabrizio Sassi, 15 Dec 2022
The manuscript attempts to discuss the Q2DW amplitude as it is affected by the phase of the QBO. It uses MERRA2 model output and SABER observations.
I cannot recommend this manuscript for full review. The manuscript is badly written; several setences are incomplete; some figures are difficult to read (especially Figure 3: impossible to read on paper, I had to blow it up to 400% digitally). The introduction is more of a QBO review, rather than a Q2DW discussion; the Q2DW comes in as an after thought. The methodology doesn't explain clearly what is done: there is some jumping between westward and eastward propagating modes, complicated by the different phases of the QBO; Q2DW events are undefined (maximum amplitude? compared to what? Are those events even statistically significant?). There is an apparent fundamental confusion between critical layers and barotropic instability. Greek (or whatever else) fonts are not rendered in the PDF docuemnt. The description of what SABER does is muddled with the satellite TIMED: for example, SABER doesn't observe anything about the ionosphere, as stated Section 2.
I recommend the authors simplify the manuscript which might have merit eventually, but certainly not now. Do not try to do a QBO review; there are already plenty of those around in the literature. Decide which mode is the focus of your study and conduct a statistical analysis of the signifcance of the perturbation you detect. Be specific about the Q2DW; there is too much confusion in this manuscript.
Citation: https://doi.org/10.5194/acp-2022-778-CC1 -
CC2: 'Reply on CC1', Paul PUKITE, 29 Dec 2022
Valid take. For example, the acronym Q2DW should be spelled out on first usage.
The paper is essentially a qualitative analysis based on anecdotal observations. Until there is a beakthrough on the fundamental mechanism behind QBO reversals, this will be a typical paper. Any discussion of a perturbation is moot without an understanding of the mechanism being perturbed.
Yet, any paper may have benefit as it may provide some insight. Such as this passage:
<i>"changes between Q2DWs and migrating diurnal tides. In addition, the short-term variation of migrating diurnal tides may be caused by the nonlinear interaction between tidal waves and Q2DWs (Chang et al., 2011)"</i>
The QBO data is highly filtered and perhaps the key is analyzing the daily time-series.
Citation: https://doi.org/10.5194/acp-2022-778-CC2 - CC3: 'Reply on CC2', Paul PUKITE, 12 Jan 2023
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CC2: 'Reply on CC1', Paul PUKITE, 29 Dec 2022
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RC1: 'Comment on acp-2022-778', Anonymous Referee #1, 27 Feb 2023
Review of the manuscript “On the Quasi-2-Day Planetary Waves in the Middle
Atmosphere During Different QBO Phases” by Tang et al.
In this manuscript, Tang et al. investigate the relation between the Quasi Two-Day Waves (QTDW) with Wavenumber 3 and 4 (W3 and W4) in the middle atmosphere and the easterly and westerly phases of the Quasi-Biennial Oscillation (QBO). They use SABER atmospheric data to obtain the QTDW amplitudes, and MERRA-2 data to constrain the QBO phases and background conditions. The manuscript reports the variability of W3 and W4 in the QBOW and QBOE phases. The amplitudes of the zonal winds and QTDWs differ between the QBOE and QBOW phases, as well as between the southern and northern hemispheres. The authors attribute the enhanced amplitudes of W3 and W4 during the QBOW to the stronger mean flow instabilities and background winds in the mesosphere. Despite the manuscript's extensive data analysis of W3 and W4 of QTDWs under the two phases of QBO, the writing style and presentation of the results make it confusing and difficult to understand. Therefore, I cannot recommend the manuscript for publication in ACP in its current format. Detailed comments are provided below.
Major comments:
- While the title of the manuscript suggests that it is a study of QTDWs, the introduction section may give the impression that the authors are primarily interested in the QBO and its effects on QTDWs. To better reflect the main aim of the study, the authors should revise the introduction section to focus on the investigation of QTDWs and their relationship to different phases of the QBO. In the revised introduction, the authors should clearly state the research question or hypothesis, provide a brief background of the topic, and explain the significance of the study.
- The authors may consider providing a paragraph in the revised introduction briefing on previous works on QTDWs based on ground-based MF and meteor radars, particularly in equatorial regions where the QBO is stronger
- The title of the manuscript suggests that QTDWs are observed in the middle atmosphere. However, this term was not explicitly used in the manuscript. Therefore, to avoid confusion, the authors should provide a clear definition of the middle atmosphere in the introduction section. Furthermore, it is important to clarify that the QBO occurs in the stratosphere, while the QTDWs are observed in the mesosphere and lower thermosphere. This clarification will help readers to better understand the vertical location of the phenomena being studied and the relevance of the QBO to the study.
- In the methodology section, the authors should explain the process of extracting the wavenumbers and why W3 and W4 are chosen. They should also provide a clear explanation of why W3 and W4 are obtained at different heights.
- The manuscript contains several technical terms, such as W3 and W4, easterly and westerly zonal winds, QBOW and QBOE, NH and SH, and GPH, which may make it challenging for some readers to follow the main focus of the results. To improve the readability and accessibility of the manuscript, the authors should consider defining these terms and providing sufficient context for their use. Additionally, they could consider simplifying the language where possible to help ensure that the main ideas are clearly conveyed.
- The authors should highlight the main results of the study, and explain clearly what is new and what is already known. They should also explain the significance and implications of their findings.
- The authors should separate the results and discussion sections to make it easier for readers to understand what is already known and what is new. The summary and conclusion section should also provide a clear and concise overview of the main findings of the study and their implications
By addressing these concerns, the manuscript should become clearer and more accessible to readers.
Minor corrections (not an extensive list, there are many)
Abstract: Please rewrite the abstract, and make sure to mention the most important results.
Introduction: Please rewrite the introduction, as it currently reads like a small review of QBO. Instead, focus on the QTDW and its variability, and explain why it is important to study it under different phases of QBO. This information is already present in the manuscript, but it needs some re-arrangement.
Section 2: The authors mention that the SABER data is from 2002 to 2020 (lines:186-187), whereas the MERRA 2 data is from 2003 to 2020. It is recommended that the authors use the same period of data from the two datasets.
Lines 150-151: There is a typo in the expansion of “MERRA 2”.
Lines 233-236, Figure 1: The zonal winds vary from negative to positive, not the amplitude. The amplitude cannot be negative.
Lines 246-247: The first sentence of the paragraph is incomplete and needs to be revised for clarity.
Lines: 247-250: It is important to explain why these specific heights were chosen for W3 and W4, and why different heights were used for each.
Figure 3: The letter 'E' is missing for 'QBOE' in the titles of sub-plots B5, C5, and D5. Additionally, the figure caption should read 'A5-D5,' not '3A-D5' if I understand correctly.
Lines 785-787: Figure 4 caption: The meaning of the sentence "The temperature amplitudes...data, respectively" in the Figure 4 caption is unclear. Please revise the caption to improve clarity. As currently written, it appears that the amplitudes of both W3 and W4 in both QBO phases were extracted from SABER data, but it is unclear if this is correct.
Figure 5: The figure is difficult to understand. It is unclear what the color-scale represents, what its units are, and where the blue shaded region is located. Additionally, it is unclear why one horizontal line is drawn for the QBO phase, and why the green line is mentioned twice, as both the critical layer and critical layer E1 with the mean period are labeled green. The authors should revise the figure and its caption for clarity.
Overall, the manuscript is very confusing and lacks clarity in presenting the important results. The text and figures also contain several typos. Therefore, the manuscript needs to be completely rewritten, with a focus on presenting the results clearly and discussing them in a way that highlights what is new compared to what is already known. Additionally, the introduction should clearly state what the authors want to study, and the manuscript should have a logical flow that leads the reader from the introduction to the conclusions.
Citation: https://doi.org/10.5194/acp-2022-778-RC1 -
RC2: 'Comment on acp-2022-778', Anonymous Referee #2, 15 May 2023
Review on:
“On the 1 Quasi-2-Day Planetary Waves in the Middle Atmosphere During Different QBO Phases”
This article has some important results, e.g., How the W3 and W4 components of Q2DW in winds and temperature differ during QBOE and QBOW phases. It discussed the role of interaction with mean flow and source variability of planetary waves in modulating the Q2DW variabilities. However, it is not well written and logically organized, which makes it very difficult to interpret and connect one paragraph to the next. It reads like the authors are making sudden jumps from one topic to another without connecting them with previous discussion. There are many flaws on the presentations. Also, many obvious/common knowledge results are presented as if they are new findings.
Some examples are:
- Lines 15-17: “Mean…QBOW phase”. This is a characteristic of a QBO and it is very obvious.
- Lines 291-292. A sudden and unexpected jump in the description without any motivation or connection to earlier discussion.
- No explanation or reasoning is provided on why different days are chosen from different years. For example, line 298, why 13-19 is chosen?
- Line 367: No reference or description is given to what kind of diagnostic analysis has been performed here. The unit(s) of the diagnostic quantities in Figure 5 are not provided, which makes it difficult to guess it.
- Lines 485-488: ‘… GPH W3 amplitude…’ What is the meaning of this? It is not clear what this quantity is. Is it some kind of filtered out Q2DW-W3 filtered out from the GPH data?
- Line 532: The mean zonal wind amplitude of what? W3 or W4?
- A physical explanation is missing: For each of the main finding listed in the summary and conclusion, a valid and proven physical mechanism or explanation should also be provided.
Minor comments:
- Line 10: Define W3 and W4 here. Also, later in the introduction section define what direction they usually propagate.
- Line 14: Not clear, what do you mean by amplitude of zonal wind. Is it the zonal-wind due to Q2DW? W3 or W4 or of QBO?
- Line 233: same as line 14. ‘amplitude of mean zonal wind’ – how can wind have an amplitude. Do you mean amplitude of QBO in wind? Make this clear here and in later occurrences.
- Line 18: “background wind’ define the background wind. Is it ZMZW or wind other than Q2DW-W3 and Q2DW-W4?
Citation: https://doi.org/10.5194/acp-2022-778-RC2
Liang Tang et al.
Liang Tang et al.
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