Trends and Interannual Variability of Extreme Rainfall Indices over Cameroon

Round 1

Reviewer 1 Report

This paper investigates the trends and interannual variability of extreme rainfall indices over Cameroon using the gridded precipitation product, i.e., CHIRPS in the past 40 years. It is well organized and generally satisfies the scope of the journal. I would like to recommend a revision before its publication as there are some issues to be addressed:

1. This work shows a comprehensive description of rainfall extremes across Cameroon from 1981 to 2019. However, the physical mechanism of the extreme rainfall is not very clear across Cameroon, which limits the depth of this research. I would suggest the authors increase the analysis of atmospheric water vapor dynamics including sources and trajectories for the extreme rainfall events in the past decades. In addition, the references of Ma et al., 2018; 2020 would be beneficial for performing this specific topic.

Ma, Y., Lu, M., Bracken, C., & Chen, H. (2020). Spatially coherent clusters of summer precipitation extremes in the Tibetan Plateau: Where is the moisture from?. Atmospheric Research, 237, 104841.

Ma, Y., Lu, M., Chen, H., Pan, M., & Hong, Y. (2018). Atmospheric moisture transport versus precipitation across the Tibetan Plateau: A mini-review and current challenges. Atmospheric Research, 209, 50-58.

2. The authors claimed that the validation of CHIRPS data is beyond the aim of this study. As CHIRPS data is merely used for the rainfall pattern analysis in this manuscript, and the reliability of the result might be not easier to quantify if the data uncertainty is not provided in the methodology. It would be better to add some context to demonstrate the CHIRPS data quality using the in-situ observations in the five agro-climatological consistent regions of Cameroon.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The paper "Trends and interannual variability of extreme rainfall indices over Cameroon" by D.A. Vondou and co-authors examines means and trends in annual precipitation and daily extreme precipitation indices.  It is an interesting paper, but needs clarity and further explanation and discussion to be publishable.

1. Please review the text for proper English grammar.  There are several instances where sentences are unclear or awkward.
2. There needs to be a description of how trends and significances were calculated.
3. Define the indices in the captions in Figures 3 and 4.  Unless the reader is familiar with these acronyms, he/she must always refer back to page 4.
4. I am not satisfied with the wavelet results.  Significance contours are not shown, and the authors mention changes in the magnitude of various periodicities that are not convincing.  I recommend removing this section of 3.3 and Figure 5.
5. I believe more needs to be said about Figure 6, specifically the fact that in recent years (~2012-2019) there has been substantial dryness in ZFM, ZFB, and to a lesser extent ZHP.  Are there other studies or meteorological reports to back this up?
6. It might be nice to have a table of precipitation means and trends averaged over the agro-climatic zones - basically from data displayed in Figures 2-4 (similar to how the SPI is integrated over the 6 zones).  The authors could use this summary to suggest potential water management strategies.  For example, is the zone becoming wetter, drier?  Will rainfall occur more or less often, will it be more extreme?

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Thank you for inviting me to review this interesting article. This manuscript investigate the trends and interannual variability of extreme rainfall indices in Cameron. Generally, the paper is well written and the methods and results are interesting. This manuscript will be suitable for publication after revision.

1. Abstract: The abstract needs more of a ‘hook’ to engage the reader and establish the novelty of the analysis in the scientific literature. An additional final sentence about the significance of these results or repercussions they would have on the community would make the abstract stronger.
2. The Introduction section should be reorganized, provide additional information related to the methods followed in previous Studies. There is no relevant background into the methods used (at least in the introduction anyway), or statement of why this research is particularly novel aside from the study area. Maybe describe the relevance of the study and why the rainfall indices analysis in this area is particularly unique.
3. Clearly state the objective(s) in the last paragraph of the introduction.
4. I suggest to improve the discussion and the conclusion sections to put in value their results.
5. Please, explain in the discussion the limitations of the work.

Figure captions:

1. Figures 5 is blurry.
2. Figure 6 is blurry.

 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript is improved, yet there are many grammatical errors and poor word choices that need to be fixed prior to publication.

1. line 24: "south" instead of "sud"
2. line 52: "store" instead of "keep"
3. line 52: "management" instead of "control"
4. line 63: should be "precipitation and drought"
5. line 73: should be a semicolon after "[9]"
6. lines 83,84: remove "at the agro-climatic regional level"
7. line 92: "too much" instead of "a lot of"
8. line 92: remove "not indicated"
9. line 119: add "daily" before "rainfall"
10. line 120: remove "days"
11. line 125: remove "depending"
12. line 168: need space: "ithand" to "ith and"
13. line 183: sentence should start "For a" instead of "A"
14. line 206: "planning" instead of "plan"
15. line 208: "has" instead of "is"
16. line 209: "highest" instead of "most region zone with"
17. line 209: remove "value"
18. line 210: "shows" instead of "showed"
19. line 210: remove "value"
20. line 212: recommend: "that years where the highest recorded amount of rainfall (and that of the least amount) are not the"
21. line 226: "lower" instead of "moderated"
22. line 239: "less" instead of "shorter"
23. line 243: "decreasing" instead of "decreased"
24. line 247,248: recommend: "The annual R95ptot index ranges..." (RX1day is nonexistent)
25. line 254: remove "precipitation"
26. line 265: "result shows" instead of "issue point out"
27. line 266: "zones, which should" instead of "zone should"
28. line 275: "more extensive, as statistically" instead of "bigger, and statistically"
29. line 294: "1980s" instead of "decade 1980"
30. line 295: "area" instead of "areas such as ZSS"
31. line 296: "1990s" instead of "decade 1990"
32. line 297: "2010s" instead of "decade 2010"
33. line 297: recommend: start new sentence "It is evident..."
34. line 297,298: "extended throughout the country" instead of "has increasingly occurred"
35. line 315: remove "selected from those"
36. line 323: "north" instead of "nord"
37. line 325: add "reached" after "northernmost"
38. line 326: "less" instead of "a lower"
39. line 327,328: Please clarify the sentence beginning "The decrease in precipitation".  I am not sure what is meant.
40. line 328: "index" instead of "indice"
41. line 332: remove "shift"
42. line 336: remove "where much of the"
43. line 337: add "the" after "that"

Author Response

The manuscript is improved, yet there are many grammatical errors and poor word choices that need to be fixed prior to publication.

Answer : First of all we like to thank reviewer #2 for the time taken to polish the paper.

In the revised version we took intoo account suggestions and problems raised in the previous version of tha paper.

Proposed remarks appear in red in this new version of our paper.

Reviewer 3 Report

The authors have replied adequately to my comments.

Author Response

Thank you very much for time spent to improve ths manuscript

Round 3

Reviewer 2 Report

The manuscript reads much better.