Ionospheric Inhomogeneities and Their Influences on the Earth’s Remote Sensing from Space

Round 1

Reviewer 1 Report

Broader literature review in Introduction section is necessary, describing current state of studies about ionosphere influence on SAR and how it is mitigated not only in Russia but internationally as well. That would help reader to understand the scope and importance of this work.

The order of reference numbering should be checked (e.g. [27] should be [16]).

Last two sentences of conclusions could be added to acknowledgements.

Author Response

Thanks for the helpful comments
We have tried to expand the literature review in the introduction.

We have corrected the numbering of links
and generally tried to take into account the comments

Reviewer 2 Report

this is a complex study and presentation. the conclusion is good but i felt it was not extensive enough considering all the factors investigated in the study. it would benefit from some clearer interpretation on the significance of each results as a blow by blow - "this result implies this to the SAR work".  other comments in the attached annotated pdf.

Comments for author File: Comments.pdf

Author Response

Thanks for the helpful comments on our article. We tried to take into account your advice on making changes to the work, correcting spelling and stylistic errors. With regard to ionospheric models, a limited number of such models have been chosen. A study using IRI is suggested in the future.

Reviewer 3 Report

In this manuscript, the various effects of the ionospheric irregularities on the P-band signals passing through have been simulated and investigated in detail under 4 different ionospheric inhomogeneities. From the work, the authors focused on checking the dependencies of the rate of phase change and total electron concentration on dynamic conditions. Moreover, the Faraday rotation angle and phase deviation and polarization coefficient were also investigated from calculation. It is well-written.

In my personal view, it is fruitful to show us preliminary information on understanding the possible influences of the P-band waves induced by the dynamic ionosphere. The authors are suggested to consider two major concerns at below:

1.     There are many results just from the simulations, estimated from 4 ionospheric models. However, in order to demonstrating the model results, the observed parameters in practice should be involved into the simulation at least. It is better to comparing the results in theory to the measurements. Otherwise, lacking of the necessary supportive evidences, the reviewer could not verify the results you provided confidently.

2.     In the Introduction section, you emphasized the important meaning very much to investigate the propagation effects from the ionosphere. You are suggested to add some helpful contents to introduce the close progresses in previous related to your works in the manuscript tightly and then summarize the existed problems that you tried to solve here.

3.     For minor comments in detail, please refer to the .pdf.

 

The end.

Comments for author File: Comments.pdf

Author Response

Thanks for your helpful comments.

1.     There are many results just from the simulations, estimated from 4 ionospheric models. However, in order to demonstrating the model results, the observed parameters in practice should be involved into the simulation at least. It is better to comparing the results in theory to the measurements. Otherwise, lacking of the necessary supportive evidences, the reviewer could not verify the results you provided confidently.

In this paper, the results of modeling based on model problems are considered, calculations are planned and based on the use of the IRI model.

2. In the Introduction section, you emphasized the important meaning very much to investigate the propagation effects from the ionosphere. You are suggested to add some helpful contents to introduce the close progresses in previous related to your works in the manuscript tightly and then summarize the existed problems that you tried to solve here.

We expanded the introduction and tried to take into account your comments.

3. For minor comments in detail, please refer to the .pdf.

We tried to take into account your comments and improve our work

 

Reviewer 4 Report

This work studies the ionospheric impact on P-band RF waves propagation on Earth based on four electron density models and numerical simulations. Overall the paper is written well in terms of theory and simulation result presentation. My minor comments are as follows:

1) Ionospheric inhomogeneities have been observed by various ground-based and space-based systems. Have authors compared the simulation results of Faraday Rotation or TEC to any observations ? 

 

2) [Line 433] "it is necessary to consider the influence of the ionosphere at least at the level of the IRI model".

- Why the IRI model is chosen as the benchmark here? How about other models such as the TIEGCM model [1] or SAMI3 model [2] which are more specialized in ionospheric plasma irregularities. Can hardware-in-the-loop simulations with L-band space observation (e.g., GNSS) based on the TIEGCM model [3] can be an approach to validate the simulation results in your work?

[1] Roble R, Ridley E, Richmond A, Dickinson R (1988) A coupled thermosphere/ionosphere general circulation model. Geophys Res Lett 15(12):1325–1328

[2] Huba JD, Liu HL (2020) Global modeling of equatorial spread F with SAMI3/WACCM-X. Geophys Res Lett 47:14. https://doi.org/10.1029/2020GL088258

[3] Peng, Y., Scales, W.A. & Lin, D. GNSS-based hardware-in-the-loop simulations of spacecraft formation flying with the global ionospheric model TIEGCM. GPS Solut 25, 65 (2021). https://doi.org/10.1007/s10291-021-01099-x

Author Response

Thanks for your helpful comments.

1) Ionospheric inhomogeneities have been observed by various ground-based and space-based systems. Have authors compared the simulation results of Faraday Rotation or TEC to any observations ? 

Unfortunately, we did not compare with experimental data in this work.

2) [Line 433] "it is necessary to consider the influence of the ionosphere at least at the level of the IRI model".

- Why the IRI model is chosen as the benchmark here? How about other models such as the TIEGCM model [1] or SAMI3 model [2] which are more specialized in ionospheric plasma irregularities. Can hardware-in-the-loop simulations with L-band space observation (e.g., GNSS) based on the TIEGCM model [3] can be an approach to validate the simulation results in your work?

We took into account your comment and added information about other ionospheric models, as well as links to literature

Round 2

Reviewer 3 Report

The authors considered all of my suggestions and comments, I have no more concern. Thus, I recommend to accept it in present form.