Review Reports

Round 1

Reviewer 1 Report

Review of: "Comparative Study of Dayside Pulsating Auroras Induced by Ultra-low Frequency Waves" by Li, et Al.

Summary:  This paper presents two case study events where ground-based auroral observations are compared to in situ data of ULF waves and chorus waves from the MMS spacecraft.  They propose that the ULF waves are modulating the chorus wave generation by different mechanisms which in turn modulate the precipitating electrons that are causing the pulsating aurora.

Comments:

-Abstract and intro:  Can you also list the periods associated with the 2-100 mHz waves (500 to 10 seconds).  When thinking about the auroral observations it is easier to think in terms of the periods when they are on these timescales.

-Lines 79-82:  You have the energies of the electrons mixed up with the emissions.  The 6300 emission should be associated with the <500 eV electrons and the 4278 emission should be associated with the > a few keV.  This is also an over simplification, but for the purposes of this paper, such a description is sufficient.

-The field line mapping should be discussed as a possible source of uncertainty, especially because the MMS footpoints are located so close to the edge of the imager FOV, where the uncertainty in the image mapping to latitude and longitude is higher already.  The texts needs a more complete description of the area added together to create the line plots of auroral intensity and a justification as to why you chose that size area.

Overall the paper presents good observations and analysis of two pulsating auroral events and I feel that it could be acceptable for publication after minor corrections.

Author Response

We sincerely appreciate this reviewer who helps us improve this manuscript. All comments and suggestions have been taken into account. The manuscript has been modified accordingly. Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper analyzed two ULF wave events associated with dayside pulsating auroras by using conjugate observation data of the MMS satellites in the magnetosphere and ground based optical observations at Yellow River Station in Ny-Ålesund, Svalbard. 

In both events, lower-band chorus waves were observed in the magnetosphere, and the intensity of the waves oscillates at the frequency of the ULF waves. In the first event, compressional ULF waves are well correlated with the auroral intensity variations and chorus wave intensity variations, while, in the second event, correlation between the compressional ULF waves and the chorus waves were not good, but the transverse poloidal ULF waves were better correlated. The authors discussed the difference in the mechanism for the chorus wave intensity variations for both events.

I think that this kind of conjugate event studies of the dayside pulsating aurora associated with the ULF waves should be important and worth to be published in the Universe. I recommend the authors to improve the manuscript considering the comments shown in attached file.

Comments for author File: Comments.pdf

Author Response

We sincerely appreciate this reviewer who helps us improve this manuscript. All comments and suggestions have been taken into account. The manuscript has been modified accordingly. Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has been revised with a careful consideration along the reviewer’s comments. Now I recommend that this paper could be published in the Universe.

Author Response

We sincerely appreciate this reviewer who helps us improve this manuscript.