Intermittency of Gravity Wave Potential Energy Generated by Mountains Revealed from COSMIC-2 Observations

Round 1

Reviewer 1 Report

The paper investigates gravity wave characteristics in the troposphere and stratosphere over three mountainous regions using COSMIC-2 datasets. This paper quantifies key parameters and intermittency. The manuscript is well-composed, with a clear methodology and appropriately presented results. Minor revisions are recommended after addressing specific comments.

Specific Comments:

Lines 38-42:

It is advised to include citations to support the statements provided. For example, Vadas et al. (2019) exemplifies the higher order wave generation in middle and upper atmosphere over Andes region.

Vadas, S. L., Xu, S., Yue, J., Bossert, K.,Becker, E., & Baumgarten, G. (2019).Characteristics of the quiet-time hotspot gravity waves observed by GOCEover the Southern Andes on 5 July2010.Journal of Geophysical Research:Space Physics,124, 7034–7061 https://doi.org/10.1029/2019JA026693

Lines 83-110:

The time ranges of the COSMIC and Merra-2 datasets should be explicitly specified for clarity.

Line 126:

Have you considered the bias reported by Liu and Chen regarding Torrence and Compo’s wavelet method favoring large scales or low-frequency oscillations? (Chen et al. [2016] said that Torrence and Compo’s wavelet method "is biased in favor of large scales or low-frequency oscillations")

Liu, Yonggang, X. San Liang, and Robert H. Weisberg. "Rectification of the bias in the wavelet power spectrum." Journal of Atmospheric and Oceanic Technology 24.12 (2007): 2093-2102.

Chen, C., X. Chu, J. Zhao, B. R. Roberts, Z. Yu, W. Fong, X. Lu, and J. A. Smith (2016), Lidar observations of persistent gravity waves with periods of 3–10 h in the Antarctic middle and upper atmosphere at McMurdo (77.83°S, 166.67°E), J. Geophys. Res. Space Physics, 121, 1483–1502, doi:10.1002/ 2015JA022127

Line 136:

Is gravitational acceleration here a constant value or a variable along altitude? 

Line 358:

Contradictory statements are noted regarding the intermittency over the Tibet Plateau and Rocky Mountains. Around line 293 it says over the Tibet Plateau, “The percentile ratio ε was the largest (0.3–0.4) at 20–30 km from May to October”. Why here it says, “The weakest intermittency at ~20–30 km … in all months”? Likewise, I have the same confusion for statements about the Rocky Mountains.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

One suggested change: qualify Conclusion 1 (line 392) to say that the intensity of EPBs was reduced in this longitude sector.  In the Goncharenko et al review (2021), one of the points is that because of the semi-diurnal nature of SSWs, the effect at low latitudes (enhancing or reducing EPBs) depends in part on location.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Overall, the manuscript is very interesting and well written. The authors investigated the atmospheric Gravity Waves (GWs) developed over the three significant mountain ranges of their interest.  These are the Rocky Mountains and the Tibetan Plateau in the Northern Hemisphere and the Andes in the Southern Hemisphere.  This is a very solid and detailed work.  The authors employed a whole range of scientific equations -constructed scientifically correctly- in order to derive the probability density function (PDF) for describing the intermittence of gravity wave potential energy (GWPE). The study areas are large, covering three mountain ranges.  The authors also used a large volume of COSMIC-2 temperature data and MERRA-2 wind data: covering the time period of almost three years between December 2020 and November 2023.  The authors selected study areas (i.e. mountain ranges) that are significantly different from previous study areas (covering Antarctica, the Southern Ocean and the tropical region).  Innovatively, to compare results and highlight differences within the overall study area, the mountain ranges of interest show both similarities and differences.  While the Rocky Mountains and the Andes are aligned in the north-south direction and have similar land-sea contrast, the Tibetan Plateau is aligned in the east-west direction and have different land-sea contrast. The results are presented and explained scientifically correctly.  It shows that the authors put a lot of work and effort into this study.  

In order to improve section 4, the authors should summarize the results (described in L273-338) in 1 or 2 tables. 

There are also some minor corrections recommended to the text:

L63: “land–sea contract” should read “land–sea contrast”

L67: “land–sea contract” should read “land–sea contrast”

L79: “GWPE” is not defined in the text (only in the Abstract). Therefore, “GWPE” should read “gravity wave potential energy (GWPE)”

Therefore, I recommend minor revisions.

Author Response

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Author Response File: Author Response.docx