GEOPHYSICAL RESEARCH LETTERS
Robert Winglee, Space Sciences Editor
American Geophysical Union
2000 Florida Avenue, N.W.
Washington, D.C. 20009
Editor's Assistant: firstname.lastname@example.org
December 29, 1997
Dr. Robert B. Sheldon
Center for Space Physics
725 Commonwealth Ave
Boston, MA 02215
Re: "On the physical origin of outer radiation belt 1-10 MeV
Dear Dr. Sheldon:
We have sent your paper back to the orginal two referees for evaluation.
As you will remember from my previous letter dated October 6, 1997, I had
indicated that both referees found that the data were very interesting
but that they had major concerns about the discussion section on the
cusp acceleration process and it was these concerns that were holding
up publication of your paper.
Thier re-reviews of the manuscript indicate that the above concerns have
not been eliminated. As a result, I cannot consider your manuscript
further for publication in Geophysical Review Letters.
I am enclosing the referees' reports, which you may find helpful if
you decide to revise your paper and submit it to another journal. I
am sorry that I cannot be more encouraging at this time.
Thank you for your interest in Geophysical Review Letters.
for Robert Winglee
Space Sciences Editor
via Maura T. C. Wright
Please find enclosed a review of MS# 6091-rev2 "On the physical origin
of outer radiation belt 1-10 MeV electrons" by Sheldon et al. This
is my third review of this manuscript. Although the style and tone of the
manuscript has improved significantly from the original version, the
discussion of their proposed mechanism for populating the outer radiation
belt remains speculative. I still do not feel comfortable recommending the
manuscript for publication in Geophysical Review Letters. I rarely
encounter a manuscript that I have major reservations about after one
or two revisions. Since there has been little change between revision 1
and revision 2, I do not think it is necessary for me to review future
manuscripts again. I had very few additional comments on this version. Please
do not send the manuscript back to me again. The decision to publish the paper
is, of course, yours.
Review of "On the Physical Origin and Prediction of Killer Electron
Storms" by R. B. Sheldon et al.
Although the author has changed the title of the section A Theory of
Cusp Acceleration to Discussion, the content of the section is nearly
unchanged. This section is basically a discussion of a proposed mechanism
and is still speculative. The author in his reply to the second review
says that his goal is to show that the speculation is observationally
consistent. If so, he needs also to address comment #1 below. Even with
reply to the comments below, I am uncomfortable about recommending this
manuscript for publication in GRL.
1. From the observations it was found that the intense cusp fluxes
observed on Oct 14 were preceded by 35 hours an enhancement seen in the
radiation belts on Oct 16. Is this time scale consistent with the diffusion
time from after electrons would have been escaped the cusp trap in the
Sheldon's proposed theory?
2. The tick marks and labels for L should be included on at least
one of the panels of Figure 2. I suggest showing them on the bottom
panels. Without tick marks and labels it was difficult to follow the
discussion of this figure. There also should be mention that the
white labels in the panels correspond to day of October 1996.
3. Pitch angle is misspelled in the text.
Report to Authors
Dear Dr. Winglee
Again I regret rejecting this paper. The detection of trapped electrons in
the cusp is a notable finding and deserves publication in GRL. However,
in my view the interpretation is so faulty and shallow, this paper
should not be published. If the authors would limit the paper to the
experimental results, I would support publication in spite of the
conversational style which lacks precision.
In the first version I objected to the vaguely described acceleration
mechanism. In the second version this section was clarified enough
to convince me the mechanism was incorrect. In this last version the
same problem exists in the first paragraph of the Discussion. One
simply cannot accelerate particles repeatedly by passing them in
closed paths in a DC electric field. The field is conservative.
This third version still seems too long, philosophical and rambling. Some
new ideas are put forward, but the theoretical backup, with the exception
of particle tracing in the cusp, is lacking. The authors should
concentrate on the experimental part and justification thereof, which would
make a good GRL paper. The Discussion adds nothing but makes one
As this is my third look at the paper, I feel the authors and I are not
converging. Perhaps it needs a fresh look by another referee.
Message to Authors
The style is too casual, philosophical, and vague to inspire confidence
in the important result presented. However, if the authors insist on this
approach, I would not object. The primary problem is with the Discussion
section which still has too much speculation, questionable processes, and
unsubstantiated statements. Comments, mostly minor except for page 8,
are given in the order in which the items appear.
p.3 line 7, Van Allen (1959) is not in reference list. (Actually you may
have too much history for a GR Letter. (Van Allen, Stormer, Fermi) i.e.
you don't reference Thompson when you mention electrons.)
Fig 2. Range in L and Energy should be given on at least one section.
I gather from Fig 1 that Energy goes from 515keV to 8820 keV, but L
appears to extend to lower values than in Figure 1.
p. 6 I found the correlation between cusp and trapped electrons
unconvincing in Figure 2. A more quantitative presentation than
these color figures is needed. Also, in view of the large
variations in both cusp and outer belt electrons, cannot an argument
be made that the outer belt is the source of the cusp electrons?
p8 First paragraph of discussion. I believe the repeated gains in energy
by recirculating in a DC electric field cannot occur. The particle will
gain kinetic energy as it falls through the electric potential and lose
an idential amount of kinetic energy as it climbs back up to the
starting point. The scattering and magnetic deflections do not change
energy. How can the particle "drift without scattering, returning to
its orginal position" without losing all the kinetic energy it acquired
in the first crossing of the cusp? This point is fundamental to the
interpretation part of the paper.
p10 Even if 5 keV electrons had the same rigidity as 500 keV Oxygen ions,
(which they do not) they will not follow the same trajectories since they
grad B and curvature B drift in opposite directions and will therefore
experience different E fields.
p10 Even if the cusp trap has higher f than the dipole trap, diffusion
into the dipole is only allowed if a mechanism exists.