Jovian Periodicities (~10 h, ~40, 20, 15 min) at ACE, Upstream from the Earth’s Bow Shock, on 25–27 November 2003

Round 1

Reviewer 1 Report

This paper gives an interesting case showing that the variation of the relatively low-energy Jovian electrons may occur around the ACE location.  The authors infer that the ~10h quasi-periodic ion flux and the IMF angle phi profile are consistent with the hypothesis of a Jovian influence. The authors also point out that there exists fluctuation of the IMF with the characteristic period of radio and ion/electron emissions from the Jovian aurora.

The authors investigate the observational features of ion/electron flux and IMF at Sun-Earth L1 point, rule out the possibility of Earth origin or Sun origin of these periodical variations, and reasonably attribute these features to Jovian quasi-periodic emissions.

This work is convictive and interesting, and I recommend this article to be published.

Some minor points:

1) Check the typo in Line 46 on page 7: "<jGEOT/jGEOT>"

2) Some evidence is given in the "forthcoming paper", I suggest the authors upload this paper to the preprint website and give a ref in this article.

3) Change Figure 6 to a better appearance

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This manuscript presented a possible observation of Jovian energetic ions at 1 au.  The scientific motivation and instrumentation were described in much more detailed than the actual observations and discussion.  In fact, all of Section 2.1 and 2.2 have no bearing on the main points of the manuscript and are already described in other publications (e.g. Gold et al., 1998) can be shorten to just a single paragraph instead of two pages.  And the Discussion and Summary section is a repeated on the Abstract and Introduction sections.  All of the figures in the manuscript were poorly made and insufficiently described the observations.  For example, the main observation was around DOY 329 to 332 (~4days), but 60 days of particle data were shown in Figure 2 with no indices to show the sources of each of those enhancements.  It is said in the Figure 2 caption and the text that the Halloween series of SEP events might have contributed to the observations in DOY 329, but there were no descriptions in the Figure or caption or anywhere else about those observations and their significance in relation to the observations in DOY 329.  The authors have referenced the Lario et al., JGR, 2005 for the Halloween SEP discussion, but the reference is missing in the bibliography (along with other references as well).  It is unclear why Figure 4 and 6 were done in different energy channels (P1’ vs P2’) and the fourier analysis (Figure 5) of the periodicities is not convincing.  Figure 7 and 8 were done so dense that readers cannot depict what information they are providing.  It is said that Figure 8 provides the simulation results of the IMF configuration during the events.  But there is no description anywhere in the manuscript on what type of simulation results it is providing other than “results kindly provided by Dr. Intriligator”.

It is mentioned throughout the manuscript that a follow-on paper will describe more results to support the authors’ claim that Jovian ions (instead of upsteam events) were detected by ACE during the Nov/Dec 2003.  Hence, I recommend the authors to provide those additional results in THIS manuscript before submission.  It is unfair to ask a reviewer to pass on judgement without supporting analysis.  In addition, there are numerous errors throughout the manuscript that makes the review extremely difficult, I will kindly ask the authors to clean those up as a professional courtesy to the reviewers..  The following are a short list of the errors that I find just a quick pass of the manuscript:

Page 2, line 5-6: Put a “-“ between low energy

Page 2, line 9: define MHD

Page 2, line 22: What is “close interplanetary space”?  Never heard of this term before.

Page 2, line 27:  SEP can also last for a few hours (i.e. impulsive SEP).  See reviews by Desai and Gialacone.

Page 2, line 29: The references (1, 2) did not describe the charge states of the energetic ions.

Page 4, last paragraph: You cannot claim the origins of these ions without showing they are not upstream events.

Section 2.1 and 2.2:  Why such a detailed description of the ACE mission and its instrumentations when they were well described in other publications already (e.g. Stone et al, Gold et al., Smith et al., 1998)?  Is there relevance to your observations here that call for such a detailed discussion?

Page 7, line 17: There’s no Lario et al., JGR 2005 reference in the bibliography.  And many other references are missing.

Page 7, line 28-32: You should list those injections in Figure 2.  It is hard for the readers to correlated what you are describing here and in Figure 2.

Page 7, line 46: what is “<JGEOT/JGEOT>”?

Page 9, Figure 3: Should put an indication of when the IP shock passed the spacecraft.

Page 14, Figure 7.  It is impossible to see what you are plotting here.

Page 14, Simulation paragraph and Figure 8.  There’s no discussion on what constitute the simulation and the sub-figures are so small I can’t really tell what is what?  And I think I know where the CME is in the figure, but that’s just my guess.

Page 15-16:  Much of the discussion are repeated throughout the abstract, introduction with supporting data lacking.  

Page 16, line 42-44:  It is stated “our present study shows that between days 25-27 November (329-331), 2003 the ACE, Ulysses and Geotail satellites reveal the following features…”.  No Ulysses nor Geotail data are shown in the manuscript.

Page 16, line 51: “data to be presented in a future paper”.  This is completely insufficient for the present paper.

Author Response

Please see the attachment 

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper addresses the question whether the Jovian 10 hour and 40 minutes periodicities are seen in the energetic ion observations near the Earth. The authors use ACE  and Geotail satellite data and claim the presence of bursts in the 0.05 MeV ion flux with 10 hour periodicity, observed after the Halloween event. This is a rather surprising result, which needs more detailed discussion, in order to exclude misleading interpretations.

1.       The travel time of 50 keV protons from Jupiter to Earth is in the order of a day. It is hard to believe that sharp bursts of energetic ions of Jovian origin can be detected at Earth with 10 hours periodicities, even if scatter-free propagation is assumed.  The arrival time depends on the pitch angle of particles, which alone is capable to spread the short scale time variation of the particle fluxes. The question here is that the ion channel of the ACE EPAM instrument might be contaminated by electron impacts, which would give a natural explanation of the observations. I suggest to include a discussion on the estimation of spurious particle detection by the instrument.

2.       The pitch angle distribution of ion fluxes showed a cross-field gradient during the onset and decay phase of the bursts. The authors interpret the observation by assuming a gradient in the energetic particles density, which forms a sheet. It is not clear to me that the pitch angle distribution was taken in the spacecraft frame, or in a frame co-moving with the solar wind? In the spacecraft frame the modulation of the particle flux by the rotation of the telescope is a natural consequence of the acceleration of particles on the electric field induced by the moving solar wind. This effect should be removed, by transforming the particle fluxes into a frame moving with the solar wind (see the Compton-Getting correction). If it is not done, I suggest to perform the Compton-Getting correction for the sectored data, before further analyzing the anisotropy due to the density gradient of the particles.

3.       If, after the Compton-Getting correction, a modulation by the rotation of the telescope still exists, the size and the density gradient (magnitude and direction) at the edges  of sheet should be estimated.

4.       The authors interpretation of the 10 h periodic bursts is that the high particle density sheet moves with the magnetic field. Fourier analysis of the magnetic field angle really gave a 10 h wave (Figure 5). It is necessary to put error bars on Fig. 5, otherwise we cannot be sure in the significance of the amplitude.

Some minor remarks.

In the Introduction, in particular in 1.2 and 1.3 a discussion on the origin (magnetospheric leakage or acceleration by the bow shock) is given. This problem is not addressed in the paper (a forthcoming paper is promised about that at the end of Introduction), therefore that part should be shortened considerably.

The English of the manuscript is good. However, the quality of the figures is generally poor, in many cases the letters of the labels are very small, practically they are unreadable. 

Comments for author File: Comments.docx

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors responded to my questions, and the revised version of the paper now contains adequate explanations to my concerns. I can now recommend the paper for publication.