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LF: Re: CME directions, and particle energy

To: [email protected]
Subject: LF: Re: CME directions, and particle energy
From: "Larry Kayser" <[email protected]>
Date: Fri, 25 May 2001 20:41:07 -0400
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Alan:


Hi Larry, well I am not sure that the professionals know a awful lot about
'em.
I have been chasing this for a while and almost no information is available
in the area that I want to find information.

As I understand it a CME is erupted from the surface roughly radially
as far as the main energy is concerned. I suspect it is a little like the
stone-in-the-pond and think there may be some spreading of the energy as
the
cme travels.
I have a sense from what I have found that the "radially" is a variable as
well, the main burst apparently does not have a direct vector out from the
center of the sun, it can come out from any point from 0 to 90 degrees from
the surface, although many do come fairly close to 90 degrees.  I could also
be in a position of having totally missunderstood what I was reading of
course, but that is what I have so far.

Thus I think the professionals judge whether a CME is going to
make an impact with the Earth's magnetosphere by finding where on the
solar
surface it is generated. Thus if near the solar equator and in the middle
of
the disc, we are certainly going to get the particles. If however it is
generated off towards the limb, then the main direction will be not
pointing
at Earth so we do not get the effect.
My interest is not in what is going to give the Earth a blast, my interest
is what is going by the Earth at a radius of out to 7.5 million miles.  My
specific interest is in the near misses, I have no interest in the ones that
are going to get us a good one.

 There is another problem however, the ejected plasma mass carries a
substantial magnetic field, and the magnitude of the effect on us depends
on
the orientation of that field with respect to the Earth's magnetic field.
One direction and it passes harmlessly round the earth magnetosphere, the
other direction and it couples with the Earth's field and then particle
injection is possible. I am not sure at what stage the solar observers are
able to determine this. I believe it is this effect that means that some
supposedly big CMEs seem to have little effect on us, while a smaller one
(with the appropriate orientation) will sometimes produce big auroral
displays.
I have a direct interest in anything that is going by the Earth within a
radius of 7.5 million miles but far enough away that it is not directly
going to give us one on the nose.

So, in my experience, spotting the CMEs is only part of the story. So far
I
have tried using the Kp index to see whether there will be (or maybe 'has
been') particle injection. I also believe the Kp index may be a measure of
the particle energy (...current >> Field??)...related to the field (but I
maybe wrong!).... BIG CMEs seem give a high Kp. The point is that it
doesnt
immediately correlate with radio effects as it takes the particles a while
to work their way down from the poles to lower latitudes, and diffuse down
into the ionsphere.
Excellent.  I am wondering if I could take some of these information
elements and from them determine the direction that the CME is going and if
it is going to come, at any energy level, within the 7.5 million miles from
Earth.

I reckon at least 24 hours and maybe longer before the effect is felt in
radio terms. By then the Kp has usually dropped right back to quiet levels
again.
Certainly, I can agree, and the time lag can be up to a week from what I saw
recently in some data.

I may be talking a load of bilge but that the best I can do from my
observations.....hope it maybe of some help....I am still trying to work
up
some correlation attempts.
If anyone knows better please help me correct my naive ideas.
If we had certain knowledge of what you are talking about then the subject
would be well understood and my querry would have received the response, go
read this chapter in some book hi.  Since that hasn't happened I can assume
we are into a border area of knowledge.

One thing that would be a big help is to identify who are the worlds experts
in this area and then I can try and engage one of them in a conversation.
If anyone has any ideas then I would sure appreciate the help.  If anyone is
offended at the OFF TOPIC discussion let me know and I will go away hi.

Thanks Alan for your time and effort.

Larry
VA3LK






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