Investigation on Global Distribution of the Atmospheric Trapping Layer by Using Radio Occultation Dataset

Round 1

Reviewer 1 Report

An interesting paper with conclusive results, based on observations and hard work that is an important starting point for regular practice 

Author Response

Response to Reviewer #1:

An interesting paper with conclusive results, based on observations and hard work that is an important starting point for regular practice

Reply:

We thank the reviewer for the positive evaluation on our study. Based on GNSS radio occultation data, the statistical characteristics of global trapping layer are shown in our study. And the effect of the interaction of various background environmental factors on the generation of trapping layer is discussed. We hope that our manuscript can contribute to better understanding of the distribution and climatological formation mechanism of trapping layer.

Author Response File: Author Response.docx

Reviewer 2 Report

Figure.2 Distribution of trapping occurrence rate with season variations, This figure is too small to read. it conveys no meaning at all. Most of the drawings are unreadable. The authors must make them a bit bigger.

Author Response

Response to Reviewer #2:

Figure.2 Distribution of trapping occurrence rate with season variations, this figure is too small to read. it conveys no meaning at all. Most of the drawings are unreadable. The authors must make them a bit bigger.

Reply:

We would like to thank the reviewer for giving us constructive and supportive suggestions which would help us to improve the quality of the paper. In this revised manuscript, we have followed the review’s suggestion and major revision has been made.

Author Response File: Author Response.docx

Reviewer 3 Report

Synopsis

This manuscript used the COSMIC data to analyze the atmospheric trapping layer in terms of occurrence rate, intensity, and thickness. I have some major concerns about this study.  

1. The description of the vertical interpolation method and error analysis regarding this method is missing. This is a critical issue, since the authors interpolate the COSMIC data from the vertical resolution of 100-m to 10-m, in order to capture the thin trapping layers better.
2. References and justifications are missing for some statements (listed below with detail).
3. The results are not consistent. Compared to fig. 2, there are many more blank grids in Figs. 4, 6, and 8. Similarly, compared to fig. 3, there are many more blank grids in Figs. 5, 7, and 9.
4. The benefits of using COSMIC RO data for characterizing the trapping layer are not clear.
5. How are the conclusions compared to previous studies? Are they consistent in some aspect? Are there any new findings? References of the previous studies of the trapping layer are missing.
6. Some sentences are hard to understand, and there are many grammatical problems in the manuscript (some are listed below).

Detailed Comments:

• Missing “the” in front of “(atmospheric) trapping layer” throughout the manuscript.
• Abstract: please add the definition and significance of the trapping layer.
• Abstract: please specify what is the unit of “M” for “intensity”.
• Abstract line 3: “are” should be “is”.
• Introduction, page 1, line 4: “the” should be “an” in front of “atmospheric trapping layer”.
• Introduction, page 1, line 8: what is “sharp layer”?
• Introduction, page 1, line 11: for “environment”, do you mean “condition”?
• Page 2, paragraph 1, line 3: when defining acronym, it should be “European Centre for Medium-Range Weather Forecasts (ECMWF)”
• Page 2, paragraph 1, line 6: why “0.2~2.5km”? is that because the trapping layer only occurs in that layer?
• Page 2, paragraph 1, line 7: “is” should be “are” in front of “mainly”.
• Page 2, paragraph 1, line 9: “ECWMF” should be “ECMWF”.
• Page 2, paragraph 1, lines 10-11, “The maximum detection height of ECMWF data is 2.5km”: Which ECMWF data did Engeln use? Please verify this statement. Because for ERA data, it can reach 80 km.
• Page 2, paragraph 1, lines 11: “is” is missing in front of “over 1 km”.
• Page 2, paragraph 1, lines 12: “layer” should be “layers”.
• Page 2, paragraph 2, lines 6-8, “The successful launch …” Please note that the number of RO profiles has declined greatly recently.
• Page 2, paragraph 2, lines 11-12, “the global trapping layer… dataset.” Is there any reference to support this statement?
• Page 2, the paragraph above Table 1: please rephrase this sentence. It’s hard to understand.
• Page 2, Table 1: what is the definition of "ducting layer" based on dN/dh and dM/dh? Are these thresholds from previous literature or defined by the authors? If the former, please add references; if the latter, please add justifications and sensitivity tests.
• Page 3, the 1^st paragraph, line 1, “dM/dr” should be “dM/dh”; line 2: the second “h_m<h<h_t” should be “h_b<h<h_t”.
• Page 3, step 2, “double-weighted average”: please add references.
• Page 3, step 3, what is the specific interpolation method (references or formula)? Error analysis regarding the interpolation method is missing. The sensitivity test of the choice of “10m” is also missing. What is the result uncertainty related to this interpolation?
• Page 3, step 5, please phrase the first sentence, “from the down to top” is hard to understand. Line 2, “h_t” should be “h_m”; line 3, “h_m” should be “h_t”.
• Page 4, the 1^st paragraph in session 2.2, line 4: “of” should be “for” in front of “refractivity deviation”; “believed to be” is redundant.
• Page 4, the 2^nd paragraph in session 2.2: what level 2 wetPrf data was used? The re-processed one or the post-processed one? Line 1, “humidity” is redundant.
• Session 3.1: Before showing the result, could you please add a global distribution of the data count within the 2_deg by 2_deg grid used for the analysis? also, could you please add another figure showing the number of trapping layer concurrences within the 2_deg by 2_deg grid?
• Figure 2: According to the definition of the "occurrence rate" given in the text, the sum of the value of a grid shown in these four panels should be 1. However, it seems that it will be over 1, for example, the red region near the west of Mexico for all four seasons. This may be due to the large scale of the plot. Could you please add figures showing a zoom-in region?
• Page 5, the 1^st paragraph: References are missing to support the statement: “The trapping layers on the west coast of America and Africa are roughly correspond to the regions where stratocumulus clouds are prevalent.” “The north-south coverage of western Mexico sea area is roughly the same as the north-south coverage of the California Cold current.” “The western North Africa Ocean is affected by the Canary Cold Current.” “The western South Africa Ocean are also affected by Benguela cold current and the southeast trade wind.”
• Page 5, the 1^st paragraph: please rephrase “The north-south coverage of western Mexico sea area is roughly the same as the north-south coverage of the California Cold current.” It’s hard to understand.
• Page 5, the 1^st paragraph, line 4: “are” is redundant before “roughly”.
• Page 5, the 1^st paragraph, line 14: “are” should be “is”.
• Page 5, the 1^st paragraph, line 19: missing “is” in front of “even”.
• Page 7, the 1^st paragraph, line 2: “With” should be “As”.
• Page 7, the 1^st paragraph, line 6: “increase” should be “increasing”.
• Page 7, the 1^st paragraph, line 13: “altitude” should be “altitudes”.
• Page 7, the paragraph below Fig. 5, line 6: “are” is redundant in front of “mainly”.
• Page 7, the paragraph below Fig. 5, line 7: “of” is redundant in front of “Mexico”.
• Page 7, why not using the averaged dM/dh for the intensity? Please show some examples showing the actual am, as values when calculating the intensity.
• Page 8, the paragraph below Fig. 6, line 1: “a” is missing in front of “high”, “have” should be “has”.
• Page 8, the paragraph below Fig. 6, line 6: “of” is redundant in front of “Australia”.
• Page 8, the 2nd paragraph below Fig. 6, line 2: missing “a” in front of “stronger”.
• Page 9, the 1^st paragraph, line 3: “layer” should be “layers”.
• Page 9, the paragraph below Fig. 8, line 1: “a” is missing in front of “high”.
• Page 10, the paragraph below Fig. 9, line 2: “area” should be “areas”.
• Page 10, the 2nd paragraph in session 4, line 1: “rate” should be “rates”.
• Page 10, the 3^rd paragraph in session 4, line 5:” increase” should be “increased”.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

I thank the authors for considering my initial review. I still have the following questions:

1. In the new fig. 3, there are latitudinal bands of larger data count near 25^o and 50^o in both NH and SH. Could the authors check whether it’s artificial? Or why is that?
2. Also in figure 6, there are several obvious horizontal light blue lines: e.g., ~ 40^oS for LT00, ~15^oN and ~40^oS for LT06, ~25^oN, 10^oN, and 40^oS for LT12, and also ~60^oN for LT18. Could the authors check whether it’s artificial? Or why is that?
3. Suggestion to fig. 3 and fig.4 is that make the zero value blank. Therefore, it’s easy to see the consistency between figure 4 and the following figures.
4. The authors haven’t specified which ECMWF data was used in this study. For example, analysis data, reanalysis data (ERA5? MACC? ERA-20CM)?

Detailed comments:

• Missing “the” in front of the “trapping layer” throughout the manuscript.
• Page 1, introduction, line 4: missing “the” in front of “vertical”.
• Page 2, 2nd paragraph, line 11: missing “is” in front of “almost”.
• Page 2, 3rd paragraph, line 13: missing “is” after “Due to”.
• Page 3, 1st line below equation (2): missing “as” after “classified”.
• Page 3, last line: “indicate” should be “indicates”.
• Page 4, the paragraph above 2.2, line 4: “time” should be “times”.
• Page 6, 2nd line below figure 5: “rate” should be “rates”.
• Page 6, 5th line below figure 5: “decrease” should be “decreases”.
• Page 7, 2nd paragraph, line 14: missing “the” in front of “same”.
• Page 9, 2nd to the last line above figure 8: “altitude” should be “altitudes”.
• Page 10, 8th line below figure 9: missing “the” in front of “other”.
• Page 11, 3rd line below figure 10: “rate” should be “rates”, missing “is” in front of “above”.
• Page 11, 5th line below figure 10: “these” should be “this”.
• Page 13, 2nd line below figure 12: redundant “a” in front of “large”.

Author Response

Please see the attachment.

Author Response File: Author Response.docx