Response to Reviewer #1 of Manuscript 2005GL022854 The Authors would like to thank the reviewer for his/her valuable comments. We have responded to all comments and have revised the paper in light of them. Details of our responses to each comment are shown below. Reviewer Comments Reviewer #1 Evaluations: Science Category: Science Category 3 Presentation Category: Presentation Category B Annotated Manuscript: No Anonymous: Yes Referrals: No Highlight: No Preference Reviewer #1(Formal Review): Review of 2005GL022954, "The correlation between mid- latitude trough and the plasmapause," by E. Yizengaw, H. Wei1, M. B. Moldwin, D. Galvan, L. Mandrake, A. Mannucci, and X. Pi General Comments The paper studies the relationship between the ionospheric light ion trough and the equatorial plasmapause, specifically trying to show that the trough is the ionospheric signature of the plasmapause. To the best of my ability to judge, the physics topic of this paper is not only similar to, it is IDENTICAL to another manuscript submitted to GRL (which I was also asked to review): 2005GL022854, "The altitude extension of the mid- latitude trough and its correlation with plasmapause position" by Endawoke Yizengaw, Mark B. Moldwin The first author is the same. The titles are nearly the same. The data used (IMAGE data and TEC data) are the same. The analysis of the data is slightly different in the two manuscripts, but ultimately, seeks to establish the same point: the correspondence between the plasmapause and the light ion trough. Why not combine the analysis into one paper? As far as I can tell, there is only an incremental difference between the current manuscript (2005GL022954, "The correlation between mid- latitude trough and the plasmapause"), and the already-submitted manuscript (2005GL022854, "The altitude extension of the mid- latitude trough and its correlation with plasmapause position").

Due to this almost mirror- like similarity between the two manuscripts, I recommend against publication of this current manuscript in GRL. I recommend that if the authors wish to publish the second study, they greatly expand their analysis and submit the paper to another journal. I will temper my judgement with the following remark: If the current manuscript (which I am now reviewing) was actually submitted first (before the other manuscript which I also reviewed), then I recommend they withdraw the other manuscript from GRL's consideration, and re-submit the current manuscript. In effect, the lead author must decide which paper should be published by GRL. One or the other must go, in my opinion, since they are essentially the same paper. We appreciate for the comment given by the reviewer. Here, we would like to remind the reviewer, as he/she emphasize in his/her comments, that even if the two papers (paper number 2005GL022954 and 2005GL022854) seek to establish the same point, they have totally different approach and analysis. The primary aim of Paper no 2005GL022954, which is the present paper, is to demonstrate the global agreement between the footprint of the plasmapause and the ionospheric mid-latitude trough. However, the objective of the second paper (paper no 2005GL022854) is to unequivocally conceal that the plasmapause is field aligned with the mid-latitude trough. We did this by tracing the mid-latitude trough and plasmapause as function of altitude. Thus, we highly believe that these two papers unambiguously nailed the long standing conjecture of MI coupling. The present paper was submitted to Science before. However, it was expelled by Science before it was sent to reviewer and submitted to GRL. Specific Comments Taking into account the possibility that this manuscript does get published, I think it appropriate to include a few brief comments. - The manuscript seems somewhat hastily written, with occasional (although not overwhelming amounts of) grammatical/syntax and typographical problems--which I do not list here. I leave it to the authors to resolve these copyediting problems by actually thoroughly reading the manuscript. Problems of this sort (while minor) should definitely not appear in print. Thank you very much for the comment. We have revised and corrected all those minor comments raised by the reviewer. - Figure 1. The format is unconventional, with latitude plotted in the equatorial plane (rather than L-value). The introduction to this figure is minimal--if one is going to use such an unconventional (and, I point out, misleading until one squints closely at the plot and realizes that not L but LAT is plotted) format, some more accompanying text is in order. However, I recommend plotting versus L in the equator, and versus LAT in the ionosphere. Lest I seem too stodgy, I think that with proper careful introductary text, with very careful notes of what is plotted, AND with some indication of why such an unconventional format is used, this format might work. It's certainly novel, if nothing else.

First we would like to thank the reviewer for the important criticism that he/she raised here. We full respect of the reviewer’s comment and we have now revised our figure and plotted in the way that reviewer advised. - Figures 2 and 3: The agreement between the mapped plasmapause, and the global VTEC measurements seems not very solid to me. Some more quantitative analysis and comparisons are in order. I can see a superficial, global agreement, but not enough to be convincing. The authors casually mention a 5-degree difference between the plasmapause and the ionospheric trough. Depending on latitude, this can be significant. The following table of dipole-B mapping illustrates: LAT dipole L 45 2 50 2.4 55 3 60 4 65 5.6 70 8.5 True, the authors are focusing on low-latitude effects (which lessens the problem), but even there the disagreement can be as large as 0.4 L to 0.6 L. In short, I think some more careful analysis and more thoughtful commentary is necessary for this result to be publishable. We have now added additional panel, in Figure 2 and 3, which clearly and precisely show the plasmapause and trough minimum separation in a quantitative way. Thus, this additional quantitative analysis can answer the ambiguity that the reviewer commented. Thank you very much for the valuable comment.

Response to Reviewer #2 of Manuscript 2005GL022854 We thank you for the important comment given by this reviewer. We have responded to all comments and have revised the paper in light of them. Details of our responses to each comment are shown below. Reviewer #2 Evaluations: Science Category: Science Category 2 Presentation Category: Presentation Category A Annotated Manuscript: No Anonymous: Yes Referrals: No Highlight: No Preference Reviewer #2(Formal Review): Science Category 2. With a lot of goodwill I rated it Science Category 2 because significant clarification/revision is needed and there is some unclear or incomplete scientific reasoning in the paper. If they can overcome the current short comings and truly show that there is a good solid correlation the IMAGE and the ground based data then there is significant new science in the paper. I strongly encourage the authors to do so. Thank you very much; we have now revised the paper. Major Issues. Presumably the vertical TEC-s are only measured over land where there are GPS instruments and interpolated over the other areas. However the maps of figure 2 and 3 are shown to be global maps including oceans etc. I do not understand how global maps based on such wide area interpolations (Page 3 paragraph 3) can be used to perform detailed comparisons, which is the main subject of the paper. I recommend that the authors should either justify why they can use such large scale spatial interpolations or restrict their studies to selected longitude regions where real regularly spaced ground based measurements exist. About 200 GPS receivers around the globe are incorporated in developing GIM. Although these GPS receivers are distributed over the land, spatial interpolation over the globe is possible using pixel -based methods, where widely separated regions can be repossessed independently of each other. The TEC predictions from climatological models are also incorporated as simulated data to bridge significant gaps between measurement data. The time sequences of global TEC maps are formed by incrementally updating the most recent retrieval with the newest data as it become available. Details of interpolation technique can be found in Mannucci et al. [1998]. It would also be much better to show the correlations in some more quantitative way such as line plots as a function of latitude or longitude rather changes in colors on a map.

We have adopted the comment and included line plots as a function of longitude at the bottom of Figure 2 & 3. Thank you very much for the comment. On page 9 2nd paragraph the authors indicate that there are significant differences between the two hemispheres. Since the IMAGE EUV data is not hemisphere specific, there cannot be differences between hemispheres and at the same time agreement with IMAGE EUV data. In the 2nd paragraph, page 9, the authors would like to remind the readers about the density structure difference between the conjugate hemispheres. The authors did not mean that the agreement between plasmapause and trough in the conjugate hemisphere are different as the plasmapause does not have any hemisphere difference. However, the density structure is different with more density structure in the south compared to the northern hemisphere. The reader has the impression that only 2 cases were found where correlations existed but that the findings would not stand up to a rigorous and extensive study using a significant number of cases. The authors have performed extended simultaneous comparisons for about four months. Due to the available of IMAGE EUV data, we have performed about 40 simultaneous comparisons. We have now included a statement in the paper that clarifies the statistical analysis of our comparison. Until these questions are addressed I do not recommend the paper for publication in GRL. I will not include a list of minor issues to be addressed at this point.