Ducting of incoherent scatter radar waves by  field-aligned irregularities

Rietveld, Michael T.; Senior, Andrew

doi:https://doi.org/10.5194/angeo-38-1101-2020

Articles | Volume 38, issue 5

https://doi.org/10.5194/angeo-38-1101-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Special Issue on the joint 19th International EISCAT Symposium...

https://doi.org/10.5194/angeo-38-1101-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 38, issue 5

Regular paper

|

22 Oct 2020

Regular paper |

| 22 Oct 2020

Ducting of incoherent scatter radar waves by field-aligned irregularities

Michael T. Rietveld and Andrew Senior

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Final revised paper (published on 22 Oct 2020)
Supplement to the final revised paper
Preprint (discussion started on 06 Apr 2020)
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Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: '{Review of "Ducting of incoherent scatter radar waves by field-aligned irregularities"}', Anonymous Referee #1, 19 Apr 2020
- AC1: 'Response to referees’ comments on “Ducting of incoherent scatter radar waves by field-aligned irregularities” by Michael T. Rietveld and Andrew Senior.', Michael Rietveld, 09 Jun 2020
RC2: 'Reviewer report of Ducting of incoherent scatter radar waves by field-aligned irregularities', Anonymous Referee #2, 20 Apr 2020
- AC2: 'Response to referees’ comments to “Ducting of incoherent scatter radar waves by field-aligned irregularities” by Michael T. Rietveld and Andrew Senior.', Michael Rietveld, 09 Jun 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Publish subject to revisions (further review by editor and referees) (14 Jun 2020) by Noora Partamies

AR by Michael Rietveld on behalf of the Authors (21 Jun 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (28 Jun 2020) by Noora Partamies

RR by Anonymous Referee #2 (29 Jun 2020)

RR by Anonymous Referee #1 (03 Aug 2020)

Suggestions for revision or reasons for rejection

Review of revision of "Ducting of incoherent scatter radar waves by field-aligned irregularities"

{\bf General comments}

The authors have added important and helpful comments and figures to the paper. However, the new text and new figures have also introduced some new questions, discussed below. I'd suggest that the new text be clarified, just as clarification helped improve the original text.

\bigskip
{\bf Specific comments}

My doubts are mainly about the interpretation of figures 2 through 5. This is is related to the new figure 4, which adds more clarity to the paper, but also adds some confusion.

Is the peak in the upper right panel of figure 4 the maximum at 150, or is it clipped?

Assuming it is the maximum, does the upper right panel of figure 4 agree with figure 2 in regard to ray density close to the magnetic field? In figure 4, at say 2 km perpendicular, the ratio of peak at 0 km to number of rays at 2 km is maybe 3 or 4 or 5, while in figure 2 it might be (2/1)**2 or (3/1)**2 i.e. something like 4 to 9. Maybe there are not enough rays in figure 2 to see that clearly.

As mentioned, the density of rays along the field in the upper right panel of figure 4 appears to be about 3 to 5 times larger than nearby rays. Figure 3 suggests an additional increase in that ratio, again by something like 4 to 9, for a total of 12 to 45. Yet in figure 5, right panel, that same ratio, between the number of rays at 0 vs 2 km perpendicular (or ground distance) looks like about 1.1 or 1.2, so about 10 to 40 times less.

Perhaps this has something to do with the solid angle of a ray bundle being inversely proportional to radiated power, but these are pretty small angles so I'm not sure that has a significant effect. Also, looking at th top left panel of figure 4, the beam shape is maybe 0.8 down at 2 km perpendicular, so 0.6 considering 2 dimensions, or about a 1.6 ratio peak to rays at 2 km perpendicular, which can't explain 10 to 40 times.

I think it is clear that in figure 4, as well as in figure 3, the magnetic field lines are assumed to be vertical, as is stated in the caption to figure 2, but it could be mentioned in all three captions.

The additional figures are welcome but could perhaps have a bit more explanation in the captions, and perhaps in the text, to help avoid confusion.

Referee Report: PDF

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ED: Publish subject to minor revisions (review by editor) (03 Aug 2020) by Noora Partamies

AR by Michael Rietveld on behalf of the Authors (23 Aug 2020)

ED: Publish as is (26 Aug 2020) by Noora Partamies

AR by Michael Rietveld on behalf of the Authors (01 Sep 2020) Manuscript

Short summary

We provide an explanation for mysterious radar echoes that look like increases in electron density during incoherent scatter radar measurements made when a high-power high-frequency (4–8 MHz) radio wave is transmitted up into the ionosphere. These echoes are seen at heights from about 200 to 650 km. We suggest that radar echoes at 930 MHz are guided along the earth's magnetic field by electron density irregularities created by the powerful radio wave, similar to light in an optical fibre.