Reviewer´s comments on Manuscript 10.5194/egusphere-2025-3398

Variability and trend analysis of temperature in the Upper troposphere and stratosphere region over the tropics (Réunion), by combining balloon-sonde and satellite measurements

by

Gregori de Arruda Moreira, Hassan Bencherif, Tristan Millet, Damaris Kirsch Pinheiro

    The present manuscript deals with temperature and tropopause height measured over a tropical site, Réunion (21.10° S; 55.48° E), an island in Indic Ocean from 2006 to 2020.  Three types of measurements are used to provide data: local balloon-borne temperature profiles (SHADOZ), satellite by using GNSS-RO technique at COSMIC-1, and reanalysis data from MERRA-2. Tropopause heights are obtained using the Cold Point Temperature (CPT) and/or Lapse Rate Temperature (LRT) methods. Those measurements are compared and show a good consistency, mainly from 10 to 30 km height between SHADOZ and COSMIC-1. So, their data was combined for constructing a more refined dataset, which was then used to fit a model which considers the AO, SAO, QBO, ENSO, SSN and IOD, as the linear trend. As expected, the analysis indicated a main influence of AO and SAO oscillations in Tropopause height dynamics, as well as a decreasing trend in CPT and a slight increase in the Lapse Rate Tropopause (LRT) height.  The paper is well written and well-structured, the methodology seems to be correct, and the subject has merits and is of interest for Annales Geophysicae.  However, this reviewer has concerns about some points that should be addressed by the authors before an acceptance recommendation. The authors should provide a complete revision of the references as indicated below. Therefore, as the subject of the paper is very interesting, I am ready to recommend this manuscript for publication after taken into consideration the above points and after giving a detailed response to my comments.

Minor  comments:

-   Line 31:  “Niño” not “Ninõ”

-   Line 334:   Fig. 10 is Fig. 9 and the plots should contain a) and b).

Also, in relation to Figure 9 what are the meaning of the two slopes inside the gray rectangles?

Additionally, do the slopes lines have deviation increasing with time? Justify or correct.

References:

There are many inconsistencies in the references with works cited but not listed and listed and not cited. Although this is not a reviewer’s duty I have patiently indicated to the authors the required changes as follows.

         1. Austin, J., and T. J. Reichler, Long-term evolution of the cold point tropical tropopause: Simulation results and attribution analysis, J. Geophys. . Res, 113, D00B10, 2008.

It appears in the references list, but it is not mentioned in the text.

          2.   Astudillo et al., 2014,  Astudillo et al., 2020 and Anthes et al., 2008 are cited in text but are not in the References list.

          3. Birner  et al., 2006 is cited in text but is not in the References list.

          4. Cheng et al, 2006 is cited in text but is not in the References list.

          5. Dameris et al., 1995  is cited in text but is not in the References list.

          6. Fueglistaler et al., 2009 is cited in text but is not in the References list.

          7. Hoinka, 1998 is cited in text but is not in the References list.

          8. Li et al., 2008 is cited in text but is not in the References list.

          9.  Ladstädter, F., Steiner, A. K., and Gleisner, H. Resolving the 21st century temperature trends of the upper troposphere–lower stratosphere with satellite observations. Sci. Rep. 13, 1306, 2023. 

It appears in the references list, but it is not mentioned in the text.

          10. Morioka et al., 2010 is cited in text but is not in the References list.

          11.

Mateus, P., Mendes, V. B., and Pires, C. A. Global Empirical Models for Tropopause Height Determination. Remote Sens., 14, 4303, 2022.

 It appears in the References list, but it is not mentioned in the text.

          12.

Randel and Cobb, 1994, Randel et al., 2000, Randel and Jansen, 2013, Reid and Gage, 1981, Reid and Gage, 1984 and Reid and Gage, 1985 are cited in text but are not in the References list.

          13.  Sivakumar et al., 2006 and Sivakumar et al., 2017 are cited in text but are not in the References list.

          14. There are two references Sivakumar et al., 2011. Check what is a) and b).

          15. Santer et al., 2004 is cited in text but is not on the References list.

          16. Saji et al., 1999 is cited in text but is not in the References list.

          17. Selkrik, 1993 is cited in text but is not in the References list.

         18. 

 Sterling, C. W., Johnson, B. J., Oltmans, S. J., Smit, H. G. J., Jordan, A. F, Cullis, P. D., Hall, E. G., 400 Thompson, A. M., Witte,J. C. Homogenizing and Estimating the Uncertainty in NOAA's Long Term Vertical Ozone Profile Records Measured with the Electrochemical Concentration Cell Ozonesonde, Atmos. Meas. Tech. 11, 3661-3687, 2018.

It appears in the References list, but it is not mentioned in the text.

         19.

 Thompson, A. M., Witte, J. C., Sterling, C., Jordan, A., Johnson, B. J., Oltmans, S. J., and Thiongo, K. First reprocessing of Southern Hemisphere Additional Ozonesondes (SHADOZ) ozone profiles (1998-2016): 2. Comparisons with satellites and ground-based instruments. Journal of Geophysical Research: Atmospheres, 122, 13,000-13,025, 2017.

It appears in the References list, but it is not mentioned in the text.

          20.

 Xian, T. and H.omeyer, C. R. Global tropopause altitudes in radiosondes and reanalyses, Atmos. Chem. Phys., 19, 5661–5678, 2019.

It appears in the References list, but it is not mentioned in the text. 

         21. 

Wang   , J. S., Seidel, D. J., and Free, M. How well do we know recent cl imate trends at the tropical tropopause? J. Geophys.  Res. Atmos. 117, D09118, 2012.

Weyland, F., Hoor, P., Kunkel, D., Birner, T., Plöger, F., and Turhal, K.: Long-term changes in the thermodynamic structure of the lowermost stratosphere inferred from reanalysis data, Atmos. Chem. Phys., 25, 1227–1252, https://doi.org/10.5194/acp-25-1227-2025, 2025.

Witte, J. C., Thompson, A. M., Smit, H. G. J., Fujiwara, M., Posny, F., Coetzee, G. J. R., Northam, E. T., Johnson, B. J.,  Sterling, C. W., Mohamad, M., Ogino, Shin-Ya, Jordan, A., and da Silva, F. First reprocessing of Southern Hemisphere ADditional OZonesondes (SHADOZ) profile records (1998-2015): 1. Methodology and evaluation, J. Geophys. Res. Atmos., 122, 6611-6636, 2017.

Witte, J. C., Thompson, A. M., Smit, H. G. J., Vömel, H., Posny, F., and Stübi, R. First reprocessing of Southern Hemisphere ADditional OZonesondes profile records: 3. Uncertainty in ozone profile and total column. Journal of Geophysical Research: Atmospheres, 123, 430 3243-3268, 2018.

Appear in the References list but are not mentioned in the text.

         22.  WMO,1957 is cited in text but is not in the References list.

The authors presented a manuscript entitled, “Variability and trend analysis of temperature in the upper troposphere and stratosphere region over the tropics (Réunion), by combining balloon-sonde and satellite measurements”.  Integration of datasets from various instruments, such as SHADOW, COSMIC-1, and MEERA-2, was used in the manuscript to assess the temperature in the upper Troposphere and Stratosphere region. The results are consistent. However, I identified some moderate-to-major issues that I believe should be properly addressed before the manuscript can be considered for publication. Below, I provide some major comments, along with minor corrections.

Major comments:

• The manuscript title emphasizes more on troposphere temperature rather than height; however, in the abstract part more emphasis is given to height relatively which break the flow/continuity (as per title). Hence, either the abstract can be modified accordingly, giving more emphasis on temperature, or the title can be modified (such as “Variability and trend analysis of temperature and height in the upper troposphere and stratosphere region over the tropics (Réunion), by combining balloon-sonde and satellite measurements”).
• In the introduction part, the authors has to discuss, the possible gaps in the previous study (if any) and how this study fill the gap/improves the existing results or different from the previous study.
• In the methods section, three methods (radiosonde, COSMIC-1, MEERA-2) are discussed to measure the tropopause temperature and height. What are their limitation with respect to each other and the variation in the obtained results? For analysis of temperature profile (Figure 2d,e,f), the authors are taking Tshadow_(Z) as base and calculating the T_SHADOW(Z) - T_COSMIC-1(Z) and T_shadow(Z) - T_MEERA-2(Z) . Is there any specific reason for it? What happens if we take either T_COSMIC-1(Z) or T_MEERA-2(Z) as base?
• In method section, Trend-Run linear regression model used. Is there any statistical model (linear/non-linear) that can also be used for the available dataset?
• In section 4 (Analysis of temperature profiles)

1. Section 4.2 Weekly and daily profiles: Is it weekly and daily profiles or weekly and monthly profiles? Please check
2. Under section 4.2: In the line no. 207, it is mention that “In contrast to SHADOZ and COSMIC-1 data, MERRA-2 does not show any data gap”. However, the Time-height temperature cross-section by MEERA-2 is not shown (such as Figure 3 and Figure 4). Please add a Time-height temperature plot corresponding to MEERA-2, also (if possible) for better clarity and visualization of readers.

• In the seasonal comparison section, it is mentioned that the thermal structure of the atmosphere is seasonally dependent, notably in the tropics and subtropics (line no. 238). With reference to the present study, are the obtained results valid in the region present only in the tropics and subtropics region around the globe? and how to check the robustness of the obtained results (if any)?

Minor:

• In the section 2 (under materials), experiments no. may be marked as 2.2a, 2.2b, 2.2c, respectively, as they are all different experiment. Or they can be mention in a single section separated with subsections.
• Sivakumar (2011), and Sivakumar (2011b, line no. 288) are mentioned in the citation but not marked properly in the references.
• Figure 1: mention this figure in the main text body. In the caption, please mention what the blue balloon symbol represents. In case if it represents the study area, the location of this blue balloon in the map and the provided latitude/longitude are mismatched. Kindly recheck and correct it. Also, mark the Roland Garros International Airport on the map. The latitude/longitude of the study site, Airport, and map should be in uniform (either in Decimal Degree or in Degree Minute Second). Mark the location of the map in the inset map by an arrow or a square box.
• Figure 7 & 9: mark time in years as Time (years).
• Line 144: “In this section is performed……..” may be rearranged as, “In this section, a comparison is performed among……”
• Figure 2 (d, e, f): In the caption, it mentions that the difference between Tshadow_(Z) and T_COSMIC-1(Z) is represented by black line, while in the legend it is marked as orange color. Similarly, with the Tshadow_(Z) and T_MEERA-2(Z). Please check and correct it.

Citation & References:

Most of the citations provided in the main text body are missed in the reference and vice-versa (such as in the Introduction section, the citations- Fueglistaler et al., 2009; Randel and Jensen, 2013; Astudillo et al., 2014; Santer et al., 2004; Reid and Gage, 1981, 1984, 1985; Randel et al., 2000) are missed in the reference part. Similarly, in the reference part, almost 33% references are missed/not cited in the main text body. Please check them and insert/remove accordingly.