Determining Ionospheric Drift and Anisotropy of Irregularities from LOFAR Core Measurements: Testing Hypotheses behind Estimation

Round 1

Reviewer 1 Report

The authors start with a description of the theory of the analysis of ionospheric drift under the assumptions of frozen flow and the Briggs model. They continue with a presentation of LOFAR data on ionospheric scintillation measurements under different geomagnetic conditions, and apply the analysis methods on them. They compare the resulting drift estimations with SuperDARN data on ionosopheric convection. Their main conclusion is that the assumption of frozen flow, i.e. unchanged shape of ionospheric irregularities, is often not fulfilled. It is necessary to consider temporal decorrelation effects.

The paper is generally well written and appropriate, I just have a number of minor comments that would improve the presentation.

The first issue is frequent mismatches between figure numbers in the text and the figures that are being discussed. There a numerous examples in the paper, e.g. the reference to Fig. 5 in line 97 obviously means Fig. 4b, or the reference to Fig. 7 in line 157 should point to Fig. 6. It seems that the paper has been re-arranged, with figures added or removed, without updating the figure numbers in the text. Then there is also some inconsistency concerning figure panels. E.g. in lines 160, 161 the text refers to Figure panels d, e, f, while the Figure 6, to that the text seems to refer to, has panels a1, b1, c1. The line following equation (22) states "The figures show..." without figure number, that probably should be 8.

Furthermore, Figures 2, 4, 5, and 6 are missing a color scale. What numerical values are the different colors representing?

The black line in Fig. 4b is not visible. If it is covered by the red strip, maybe the black one should be plotted on top if it.

The axes labels are barely legible in Fig. 5, and quite small in Figs. 4, 6, 7, 7, and 10. Figures 11 - 14 could also be larger, and the information in Fig. 15 is also hard to read. What are the units at the isolines in Figures 12 - 14?

Author Response

>The first issue is frequent mismatches between figure numbers in the text and the figures 
>that are being discussed. There a numerous examples in the paper, e.g. the reference to 
>Fig. 5 in line 97 obviously means Fig. 4b, or the reference to Fig. 7 in line 157 should 
>point to Fig. 6. It seems that the paper has been re-arranged, with figures added or removed, 
>without updating the figure numbers in the text. Then there is also some inconsistency 
>concerning figure panels. E.g. in lines 160, 161 the text refers to Figure panels d, e, f, 
>while the Figure 6, to that the text seems to refer to, has panels a1, b1, c1. 
>The line following equation (22) states "The figures show..." without figure number, that probably should be 8.

corrected

>Furthermore, Figures 2, 4, 5, and 6 are missing a color scale. What numerical values are the 
>different colors representing?

the figures changed (added colorbars)

>The black line in Fig. 4b is not visible. If it is covered by the red strip, maybe the black one should be plotted on top if it.

the figure changed accordingly

>The axes labels are barely legible in Fig. 5, and quite small in Figs. 4, 6, 7, 7, and 10. 
>Figures 11 - 14 could also be larger, and the information in Fig. 15 is also hard to read. 
>What are the units at the isolines in Figures 12 - 14?

corrected

 

Reviewer 2 Report

 

The authors describe a simple model with the diffraction pattern temporal decorrelation to estimate drift velocities using scintillation mode observation of LOFAR. The paper is packed with a lot of information, so somehow the original contribution does not get highlighted it should be. Also, the authors only discuss the advantages of using their model, while not discussing the errors due to this model. Therefore I cannot recommend the manuscript for publication in its current form. I explain my concerns below for the authors to consider before resubmitting.

 

P4L101: “is very close to the estimated” what estimated?

Fig 2: Is possible to have two subplots, one with red strip to show the estimated drift velocity and second without red strip, only with the “barely seen” black strip?

 

The paper is having a lot of images which need more explanation for the reader (especially the later ones, e.g., Fig 13 and 14).

P13 last paragraph: The authors should mention why and how their method is better than the previous methods.

There should be a discussion in the manuscript describing the errors resulted to the simplified assumption and it would impact the conclusion of the paper.

 

There are minor typos in the manuscript, e.g., P2 before line 34, wavelength spelling, P3L54, evolution., and others. Please read the manuscript clearly and eliminate these sorts of errors.

Author Response

>P4L101: “is very close to the estimated” what estimated?

we hope that we have resolved the ambiguity 

>Fig 2: Is possible to have two subplots, one with red strip to show the estimated drift velocity and second 
>without red strip, only with the “barely seen” black strip?

done
 

>The paper is having a lot of images which need more explanation for the reader (especially the later ones, e.g., 
>Fig 13 and 14).

we dropped these figures 

>P13 last paragraph: The authors should mention why and how their method is better than the previous methods.

some explanation is added in the discussion section

>There should be a discussion in the manuscript describing the errors resulted to the simplified assumption and it 
>would impact the conclusion of the paper.

as above 

>There are minor typos in the manuscript, e.g., P2 before line 34, wavelength spelling, P3L54, evolution., 
>and others. Please read the manuscript clearly and eliminate these sorts of errors.

we did our best

Reviewer 3 Report

Manuscripts submitted to MDPI journals should meet the highest standards of publication ethics: Manuscripts should only report results that have not been submitted or published before, even in part. Manuscripts must be original and should not reuse text from another source without appropriate citation.

My remarks:

1. Barbara Matyjasiak is not affiliated.

2. All authors are marked with ‡. What for?

3. The article was previously partially published (see link https://ieeexplore.ieee.org/document/9593828/references#references

 

DOI: 10.1109/SPSympo51155.2020.9593828.

Grzesiak, Marcin & Pozoga, Mariusz & Matyjasiak, Barbara & Przepiorka, Dorota & Rothkaehl, Hanna. (2021). Determining ionospheric drift and anisotropy of irregularities from LOFAR core measurements. 97-102. 10.1109/SPSympo51155.2020.9593828.), so it needs to be revised.

4. There are breaks in the numbering of lines in the text of the article (33-34, 36-37, 69-70, 73-74, 82-83, 108-109, 116-117, 166-167, 211-212.

5. There are typos in the text (see, for example, "Polish Cademy of Sciences" instead of "Polish Аcademy of Sciences").

My opinion: the article is overloaded with figures, the data are fragmentary, the results are quite controversial. But this article seemed interesting to me.

Please see the attachment for detailed comments

Comments for author File: Comments.pdf

Author Response

1. Barbara Matyjasiak is not affiliated.

corrected

2. All authors are marked with ‡. What for?

corrected

3. The article was previously partially published (see link https://ieeexplore.ieee.org/document/9593828/references#references

DOI: 10.1109/SPSympo51155.2020.9593828.

Grzesiak, Marcin & Pozoga, Mariusz & Matyjasiak, Barbara & Przepiorka, Dorota & Rothkaehl, Hanna. (2021). Determining ionospheric drift and anisotropy of irregularities from LOFAR core measurements. 97-102. 10.1109/SPSympo51155.2020.9593828.), so it needs to be revised.

information added in the abstract

4. There are breaks in the numbering of lines in the text of the article (33-34, 36-37, 69-70, 73-74, 82-83, 108-109, 116-117, 166-167, 211-212.

tryin hard to overcome this effect, but it is due to the tex package (we suppose)

5. There are typos in the text (see, for example, "Polish Cademy of Sciences" instead of "Polish Аcademy of Sciences").

corrected

6 (from pdf comments no. 2) In Introduction in line 16 in the main formula there is a coefficient 2, which is not given in most publications, because this formula is estimated.

this factor comes from standard formulation of difussion approximation, can be found in classic:
Yeh, K.C.; Liu, S.J. Radio wave scintillation in the ionosphere. Proc. IEEE 1982, 70, 324–360.

7 (from pdf comments no. 3) There is no explanation what is ϵ ( r ) i n formula (1) ( dielectric permittivity), and for what medium is it used.

corrected

8 (from pdf comments no. 4) There are no mentions in the article about other low-frequency interferometers, such as, for example, the GURT and URAN (UTR-2) (Institute of Radio Astronomy National
Academy of Sciences of Ukraine), facility SURA (Radiophysical Research Institute
Nizhny Novgorod State University, Russia).

we do not deal with the interferometry in this paper, each LOFAR station obseves in beam forming mode the same radio source

9 (from pdf comments no. 5) In table 1 (section 3), there are terms “quiet”, “small disturbance” and “storm-main
phase” in the column “short characteristics”. It is not clear what the degree of
disturbances is in each case. I believe it is necessary to give the values of Dst for these
notations.

plots illustating Dst index aded

10 (from pdf comments no. 6) It is desirable to show the elevation angles of Cassiopeia in Fig.8 on the right side.

elevation of the source added to the plots

11 (from pdf comments no. 7) Figure 15 shows ionospheric ionosonde horizontal drift estimation during 10/13/2016
storm at: a - Fairford, b - Juliusruh, c - Pruhonice. I believe that it is sufficient to give
only the values of the velocities in the text of the article, excluding the figures
themselves, but adding the drift data for 2016.09.20 and 2016.09.25.

as requested the values given for the most spectacular case of 13.10.2016 (main phase of the storm)

12 (from pdf comments no. 8) The velocity values obtained in the article are not typical for the mid-latitude ionosphere. Authors of the article correctly note that their comparison with superDARN data is only
possible for a qualitative comparison. In this case, to compare the drifts in the polar and
midlatitude ionosphere is not entirely correct.

we agree - that is why we stressed qualitative nature of this comparison and suplemented it with ionosonde data

13(from pdf comments no. 9) I recommend authors to familiarize with the works of V.A. Alimov:...

we find the suggested papers very interesting but somehow irrelevant in our context. we try to clarify this 
by mentioning in the text, that the measuremets are obtained not in the interferometric mode

 

Round 2

Reviewer 3 Report

Numerous errors and typos have been corrected in the article. The authors took into account all my comments. Furthermore,  they added drawings (the total number became 55!).

My remarks: Line 162 is missing the figure number (6). The time interval in Figure 7c does not match the data in Table 1. The text uses a different presentation of references to formulas (in brackets - see, for example, line 105, and without them). Figure 17 should refer to Figure 12. Figure 18 should refer to Figure 13. In line 204, add the list of figures 12 and 13.

 

Author Response

>My remarks: Line 162 is missing the figure number (6). The time interval in Figure 7c does not match the data in Table 1. 

corrected

>The text uses a different presentation of references to formulas (in brackets - see, for example, line 105, and without them). 

corrected

>Figure 17 should refer to Figure 12. Figure 18 should refer to Figure 13. 

corrected

>In line 204, add the list of figures 12 and 13.

corrected