Line 41;      I will correct the missing letter “e” in the mesosphere

Line 74-77; I will try to paraphrase and correct the sentences in Figure 1.

Figure 2 (as well as Figure 7.8) is not entirely clear; I will try to increase visibility for all these Figures

Line 140-141; In this line, you have commented, but you might not be clear in detail. Figure 2 depicts the upper and lower inversions before defining the base height.

Figure 4; shows how much the upper and lower inversions occurred in their characteristics of amplitude, height, and thickness.

The rest you have mentioned in your comment will be corrected if it needs correction.

I will include your comment in the next revised version, and I thank you for your constructive comment.

Comments on, “The Role of Gravity Waves in the Mesosphere Inversion Layers (MILs) over

low latitude (3-15° N) Using SABER Satellite Observations” by Lingerew and Raju.

Using sixteen years of SABER temperature data, the authors investigated the role of gravity waves

(GWs) in the mesospheric inversion layers. To understand the role of GWs in the MILs, they

estimate the potential energy, and based on the results they argue that the lower and upper MIL

distinctions are due to the GWs. The strength of the manuscript is they used a long-term data set

however their methodology is not clear. Moreover, this manuscript also lacks the scientific

discussion. The present form of the manuscript needs major changes before acceptance for

publication. Therefore, I recommend to the editor for a major revision. The detailed major and

minor comments are as follows:

Major comments:

1. In section 2, latitudinal information of the data used is given however there is no
   
   information about the longitudes! Which reading the whole manuscript, I could see the
   
   longitudinal limits of 32 to 48° in Figures 10 and 11 (in section 3.4). Are the temperature
   
   profiles averaged over 3-15°N and 32-48°E? If so mention it in section 2. More
   
   importantly, the information about how do the MILs are identified is missing. They have
   
   only written as a diagnostic technique is used. What kind of diagnostic technique, whether
   
   the authors validated the diagnostic method all this information should be provided in the
   
   methodology (e.g. Gan et al., 2012; Sivakandan et al. 2014, etc.).

Response: We have mentioned the criteria to separate the inversion phenomenon from the observation data in lines 87-91 from Section 2.

1. One of the major issues in the manuscript lack of a literature survey, though they have cited
   
   some of the important papers (Meriwether and Gardner 2000; Gan et al., 2012) but the
   
   essential points from those papers are not reflected in their approach. There are various
   
   sources proposed as the causative mechanism of the lower and upper MILs. For example,
   
   the planetary waves are believed to be the causative mechanism of lower MILs similarly,
   
   gravity wave tidal interactions and chemical heating are proposed as a cause of upper MILs.
   
   These points are not considered and there is no reason why the authors only focus on the
   
   GWs. It is well understood that in most of the cases the GWs breaking in the mesosphere
   
   can cause only very few Kelvin temperature changes (>10K). If this is the scenario it cannot
   
   explain the higher amplitude MILs. Comment on it.

Response: OK, thank you. We know that all tidal, planetary, and gravity waves, as well as chemical reactions, are causative of an inversion, but here in our study region between 60 and 90 km is the gravity wave, which is generated from the lower atmosphere and propagated to the upper atmosphere till to reach the saturation level for breaking and it impacts the atmospheric variability as causative of an inversion.

1. As mentioned in comment 1, the authors should provide longitudinal information, because
   
   this has an important role if they try to understand the role of GWs which are highly
   
   localized in nature. It is not clear how the 1hr cutoff frequency applies to the data, if the
   
   authors used a particular region then in a day maximum of two to three satellite passes can
   
   be observed based on the area, with this limited data set how effective or logical is the 1hr
   
   band pass filter?

Response: we have used only SABER temperature data over the low-latitude in the spatial regions from (3-15) latitude, (32-48) longitude and (60-100 km) altitude. So, as mentioned in the text, we have applied a one-hour interval cut-off frequency of the pass band filter to separate the gravity waves from those other wave activities, such as planetary and tidal atmospheric waves.

1. Why 3rd order polynomial fit? Ramesh and Sridharan (2012) do not elaborate on any
   
   method, instead they have cited Leblanc and Hauchecorne (1997). Therefore the article
   
   cited here is not relevant. Provide more information about the methodology and its validity
   
   (how good it is? if the authors did any test to validate the method etc.)

Response: OK, we can use the reference Leblanc and Hauchecorne (1997) instead of Ramesh and Sridharan (2012) based on their relevance to express the third-order polynomial fit. The 3rd-order polynomial fit is relatively good, as we understand from the scientific community, to provide the background information relative to other orders. Then after having this information we can derive the perturbations by subtracting the background from the observation data.

1. Lines 138-140; in this context, Gan et al., (2012) could be a more suitable paper to cite
   
   here than Sivakumar et al. (2001), because they also used SABER data, on the other hand,
   
   Sivakumar et al. (2001) only used Rayleigh lidar data over a single location (the data
   
   quality above 80 km is questionable). Gan et al. (2012) also found the seasonal variation
   
   of MILs in the low latitudes and planetary waves as the cause of lower MILs, whether these
   
   authors could find such a relationship? If yes or no provide reasons!

Response: It doesn’t need any reason for yes or no to use the reference (Gan et al., 2012) instead of (Sivakumar et al., 2001), because already you have mentioned why Gan is preferable to Sivakumar based on their relevance to supporting the idea about the base of the lower inversion in lines 138–140 so we simply accepted using that one.

1. There is no clear information about how the occurrence frequency is estimated. Provide it?

Response: We can calculate the occurrence rate (percentages) for lower and upper inversions by counting the number of inversion days every month from 2005 to 2020.

1. 
   
   How the mesopause altitudes are taken care or eliminated from the statistics? Which could
   
   be a false indication of inversion. And could the authors note any solar activity dependency
   
   of MILs occurrence (for example, Sivakandan et al. (2014))?

Response: We did our work about inversions and their causative gravity waves in MLT dynamic regions over low latitudes, but we didn’t consider the pous (mesopous).

1. Lines 151-155, In the literature there are different causative mechanisms are proposed for
   
   the multiple MILs, (I suggest the authors go through Meriwether and Gardner (2004); Gan
   
   et al. (2012)).

Response: OK, we will check again on their scientific investigations.

1. Section 3.2, is a good point to investigate but before doing that the data need to be binned
   
   properly with local time. I am a bit concerned about how good to investigating the latitudinal
   
   and longitudinal variations in a small region using satellite data, each temperature profile
   
   could be nearly 500 km spatial averaged.

Response: It is not local time; instead, we have used the period during 2005–2020 over the latitudinal regions (3–15) and longitudinal regions (32-48).

1. The scientific discussion is very spare and weak. They should compare the present results
   
   with earlier studies based on the similarities and differences the scientific reasoning also
   
   should be included in the manuscript.

Response: OK, we will try to elaborate the discussion based on your comment.

1. How the GWs potential energy is connected to the MILs? First establish the connection by
   
   showing a single case in which a physical connection should be clear and then go for the
   
   statistics.

Response: Relay, we have background information on how gravity waves impact the inversions of the upper atmosphere. The connection is that a gravity wave is generated from the lower atmosphere, and the wave propagates to the upper region until it reaches the saturation level over the upper region. The wave is then broken to dissipate the energy, and its energy impacts the region by increasing its temperature. In this region, the temperature increment with elevation is known as an inversion. This is the reason we connected the gravity waves with an inversion.

Minor comments:

1. Lines 8-9, The mesosphere…This is a transitional region not only in the low latitudes! So
   
   modify the statement.

Response: The Mesosphere transitional region over low latitudes is a distinct and highly turbulent zone of the atmosphere relative to mid- and high latitudes.

1. Lines 39-40, define the MILs.

Response: The Mesospheric Inversion Layer (MIL) is a feature that increases the temperature profiles in the mesosphere region.

1. Line 41, a typo, ‘mesosphere’

Response: OK, we corrected

1. Line 73, these references are irrelevant here. Provides references about the data validation
   
   and limitation as well as instrumental specifications.

Response:

1. Line 75, longitudinal information is missing!

Response: OK, we will correct it.

1. Figure 4: Sivakandan et al. (2014) also did such a statistical analysis using the SABER data
   
   over Indian low latitudes, could you compare the present results with their results and
   
   provide some scientific reasoning for the observed differences or similarities?

Response: OK, thank you. We will try to check and compare with his scientific results.

1. Line 218 …that the inversion temperature is in the range of…It is not an inversion
   
   temperature range only a temperature range.

Response: Yes, it is the inversion-day observed temperature.

1. Line 242 onwards, the longitudinal information is suddenly introduced here, it should be
   
   introduced in section 2.

Response: Ok

1. Lines 245-247, these lines are not clear. Please see the major comment 3.

Response: OK, we will elaborate

1. Figure 5b, a typo ‘thickness’ References suggested to read and compare with the present results and include in the discussion part (some of the articles are cited here but those results are not utilized to improve the discussion part):

Response: It is corrected and includes the references based on their relevance.

1. Gan, Q., S. D. Zhang, and F. Yi (2012), TIMED/SABER observations of lower
   
   mesospheric inversion layers at low and middle latitudes, J. Geophys. Res., 117, D07109,
   
   doi:10.1029/2012JD017455.
   
   2. Meriwether, J. W., and C. S. Gardner (2000), A review of the mesosphere inversion layer
   
   phenomenon, J. Geophys. Res., 105(D10), 12405–12416, doi:10.1029/2000JD900163.
   
   3. Sivakandan, M., Kapasi, D., and Taori, A.: The occurrence altitudes of middle atmospheric
   
   temperature inversions and mesopause over low-latitude Indian sector, Ann. Geophys., 32,
   
   967–974, https://doi.org/10.5194/angeo-32-967-2014, 2014.
   
   4. Ramesh, K., S. Sridharan, and S. Vijaya Bhaskara Rao (2014), Causative mechanisms for
   
   the occurrence of a triple layered mesospheric inversion event over low latitudes, J.
   
   Geophys. Res. Space Physics, 119, 3930–3943, doi:10.1002/2013JA019750.

I will include your comment in the next revised version, and I thank you for your constructive comment.

The manuscript presents an investigation of the likely effects of atmospheric gravity waves on Mesospheric Inversion Layers (MILs) in equatorial latitudes. Indeed, the topic is interesting and not explored very well by the communities. Additionally, it is within the scope of Annales Geophysicae because it is an experimental investigation of the mesosphere using satellite measurements. Before I consider the paper suitable for publication, some concerns could be explored and revised by the authors to improve the quality of the manuscript. In general, the observations present in all figures were not explained or explored very well. Consequently, I missed consistent interpretations of the present results.

1. For example, Figure 1 shows the variability of the temperature in the mesosphere and lower thermosphere, what is the objective of it? Is it possible to see MILs, where? If not, why is it not possible to see? In summary, how can Figure 1 help the authors?

Response: Figure 1 is the Temperature variability of the MLT region before separating their inversions, which is not visible.

1. Figure 2 shows upper (left) and lower (right) MILs, to be sincere, I did not understand the bottom panels. May the authors explain them better? I also suggest enlarging captions and the size of the panels.

Response: The upper panels (a) and (c) represent the upper-MLT and lower-MLT SABER observations before separating the upper and lower inversions respectively whereas the lower panels (b) and (d) represent the upper and lower inversions of the MLT temperature variability respectively. The figure will be enlarged for clarity.

1. Figure 3: what is the bin size and which criteria were used to determine the percentage of occurrence of MILs?

Response: The occurrence rate of the MIL is calculated by making the mean of the upper (80–100) km and lower (60–80) km over altitudinal temperature data during the period from 2005 to 2020.

1. Figure 4: Are the red curves indicating a Gaussian fit? If yes, please, explain it in the text. Please, note that the statistic used for panel (c) does not represent the data, in this case, the authors could use another statistic or explain what are causing the discrepancies.

Response: Yes, it is the normal distribution, also known as the Gaussian distribution, which is a probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean, and I have mentioned their statistical values. If there is a technical error, we will check for discrepancies in the distribution at (c) or mention the reason for their significant variations.

1. Figure 5: What is the relevance of these results and how could they be related to gravity waves? I guess the quality of the presentation of this figure could be improved by enlarging the caption and size. Figure 6: Same comments as Figure 5.2.

Response: Before investigating the impacts of gravity waves on the MLT inversions, we have tried to show the spatiotemporal variabilities of an inversion in Figures 5 and 6 to characterize the upper and lower inversions respectively. The figure will be enlarged for clarity.

1. I recommend the authors use a more complete expression of the potential temperature (Vadas and Fritts, 2005; Vdas, 2007) instead of what was presented in Equation (1).In addition, the discussion of atmospheric stability is very superficial and it does not include a real aspect of the atmosphere that is certainly present in the SABER data. I suggest including an example of the methodology used to calculate the MILs in the real data (section 2). In my opinion, it could help the readers to promptly understand the process.

Response: I will have used the references (Meriwether and Gardner, 2000; Garcia-Comas et al., 2008) to the methodology in Section 2 for more clarification for readers.

1. Section 3.4: The authors wrote that they used a low pass filter to exclude the effects of tidal and planetary waves in the residual signal. If I understood the process, I guess they could use high-frequency filters to maintain low periods. Indeed, the blue lines in Figure 9 show a smoothed signal that excludes short-time variations. If I am correct, Figures 10 and 11 could be revised and the interpretations as well.

Response: Thank you. Before you commented, we corrected it by using a high-pass filter (high-frequency filter) instead of a low-pass filter.

1. Lines 279-282: "The result concludes that the observation of high potential energy in the upper mesosphere region is due to the deposition of high energy and momentum at the background temperature by gravity wave breaking, which could influence the dynamics of the inversion phenomenon". Lines 291-293: "This result leads us to the conclusion that a high amount of gravity wave potential energy is a consequence of the high instability of the upper inversion relative to the lower." I guess, it is possible to reach these conclusions from the present work. Conclusions: I think it will be better to change the name of the section to Summary and exclude the last two ones that are very general.

Response: We will correct it with a summary instead of a conclusion.

Reference

1. Garcia-Comas, M., Lopez-Puertas, M., Marshall, B. T., Wintersteiner, P. P., Funke, B., Bermejo-Pantaleon, D., Mertens, C. J., Remsberg, E. E., Gordley, L. L., Mlynczak, M. G., and Russell III, J. M.: Errors in Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) kinetic temperature caused by non-local-thermodynamic-equilibrium model parameters, J. Geophys. Res., 113, D24106, doi:10.1029/2008JD010105, 2008.
2. Meriwether, J. W., and Gerrard, A. J.: Mesosphere inversion layers and stratosphere temperature enhancements, Rev. Geophys., 42, RG3003, http//doi:10.1029/2003RG000133, 2004.