Method of Development of a New Regional Ionosphere Model (RIM) to Improve Static Single-Frequency Precise Point Positioning (SF-PPP) for Egypt Using Bernese GNSS Software

Round 1

Reviewer 1 Report

 This paper presents a regional ionosphere model (RIM) based on the Egyptian CORS stations. The results conclude that the SF-PPP accuracy result improved by 60%, 68%, and 77%, in the east, north and up components, respectively when compared with GIM. However, the innovation of this paper is insufficient, and the discussion and analysis are not sufficient.

(1)   The manuscript shares similar research content and conclusions with another paper “Abdallah, A., AGAG, T., & Schwieger, V. Validation of CODE-GIM and Regional Ionosphere Model (RIM) for Single Frequency GNSS PPP Solution using Bernese GNSS software-Case Study: Egyptian Nile Delta”.

The difference between the two papers is only the addition of comparative analysis with the GIM model and the number of stations and time periods of the RIM, as well as the addition of a visual analysis of the ionospheric delay values of the two models.  What is the new idea of this paper?

(2)    A more detailed description in the introduction. For example, please list the name of the specific ionosphere function model rather than just list the reference.

(3)    Google Maps as a background makes the description of the results unclear.

(4)   The discussion works are not enough. Only the positioning accuracy of SF-PPP are used to justify the performance of the RIM . What is the performance of the SF-PPP convergence time? These results should be validated deeply.

(5)   Some of the descriptions are not described professionally, e.g. the positioning accuracy is described in the east, north and up components rather than in the east, north, and height components.

(6)    There are some spelling error in the manuscript, such as, in line 272, “DOU” would be “DOY.

Author Response

Dear respected reviewer,

I appreciate your commitment to the development of this topic and I recognize the importance of criticism in the peer-review process. Your suggestions have helped me greatly, and I think the updated work will be much better as a result. I want to thank you again for your thoughtful and helpful comments. We are really grateful for all of your efforts.

Attached a response letter.

Best Regards

Authors

 

Author Response File: Author Response.pdf

Reviewer 2 Report

1-    The title implies that the scope of the paper is a method of development of a new Regional Ionosphere model (RIM) for Egypt while the paper's content has data only for Nile Delta and the valley.

2-    in the abstract: GIM -> global ionosphere maps (GIM).

3-    Section 4, line 195, six ESA-CORS stations (CARO, MOUS, QANT, ADFO, ALEX, and SUZE), please show where the SUZE station is in Figure 4.

4-    Section 4, Line 197, Table 3 shows the availability of Rinex observation data for the different stations throughout the study period. please replace with, table 3 shows the availability of Rinex observation data for the validation stations.

5-    Section 5, Line 217, It can be seen that DOY 202 reported the least error while DOY 203 reported the greatest error. the author didn't explain the reasons.

6-    Section 5, It is apparent from this table that in the East direction, most of the stations report an average error of 0.13- 0.17 m, and in the North direction an average error of 0.33–0.44 m, and in the North direction an average error of 0.82–0.94 m. The author did not explain the reasons for these errors, it is possible that they are systemic errors and can be omitted.

7-    Section 5, Table 6 displays the observation times of the stations with low accuracy for the RIM model’s SF-PPP solution. For example, station WAKF has an observation time of 1.30 hours for DOY 201 and an observation time of fewer than 24 hours for DOY 202, 204, 205, and 206. The author explains that the reason is insufficient observation time. if these stations are not used What will change in the results?

8-    Section 5, A Matlab code has been developed to extract the VTEC values related to the longitude and latitude over Egypt to visualize the ionosphere maps. What’s the Matlab code, please explain.

9-    Figure 7 shows an example of the ionosphere maps for GIM, and the developed RIM model for DOU 201. Please indicate the time in figures a, b, c, and d.

10- The figure presents the ionosphere maps as contour maps over Egypt. According to the verification stations, we know the expected errors around them, but far from these stations in eastern and western Egypt, what is the average error?

 

11- This solution is better than the solution using the GIM model with a percentage of 60%, 68%, and 77% in East, North, and height, respectively. Please explain how these percentages were calculated?

Section 5, Line 240, The best accuracy is obtained from the static SF-PPP solution using the developed Egyptian ionosphere regional model. I think this sentence is not worded appropriately, please amend this sentence.

Line 266, Furthermore, these losses reduce the accuracy of the final SF-PPP solution. I think this sentence is not worded appropriately, please amend this sentence.

Author Response

Dear Reviewer,

We would like to express my sincere appreciation for reviewing and providing insightful feedback on my manuscript. Your comments and suggestions were extremely beneficial in enhancing the quality of the work, and we appreciate your commitment to ensuring that the peer-review process is of the highest quality.

Attached a responce letter!

Best Regards

Authors

 

Author Response File: Author Response.pdf

Reviewer 3 Report

The style of inclusion of references  in these sentences should be improved:

·       Line 53. [18] calculated the TEC values…

·       Line 59. 21] evaluated the SF-PPP…

·       Line 66.  [23] introduced…

·       Line 73. [26] developed…

Please explain abbreviation “ESA-CORS”. Abreviation ESA is used also by European Space Agency, not only by Egyptian Surveying Authority.

Line 182.    Which GIM model ?

Please change “Reciver” to “Receiver” in Figure 3.

Line 359. Please change “Avilable” to “Available”.

Author Response

Dear respected reviewer,

We appreciate your attention to our manuscript and your thoughtful comments. Thank you so much for taking the time to read and comment on our text; your suggestions have made significant improvements.

Attached a responce letter!

Best Regards

Authors

 

Author Response File: Author Response.pdf