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Re: (meteorobs) Leo peak China
> On Sun, 9 Dec 2001, Marco Langbroek wrote:
>
> > I am really starting to wonder whether the
> > predicted 4 revolutions trail (1899 dust) really has produced any
> > significant contribution to the observed activity. Rather, it would seem
> > that this could have been almost completely due to the 9, 10 and 11
> > revolution trails instead.
> Upon which Rob McNaught wrote:
> Given that this time is close to the predicted 4-rev peak, what reasoning
> do you have for assuming this is mostly down to the 9, 10 and 11-rev trails?
The peak observed is as close to the 4 rev. trail prediction as it is to the
combined 9, 10 & 11 trail predictions, actually it might be just closer to the
9, 10 & 11 trail predictions. That directly points out the problem: which peak
is which trail? People assume the main peak is the 4 rev. trail because that
was supposed to be strongest from the model predictions: but must it be so? I
was struck by the uncanny resemblance of the profile to that which you get if
you remove the 4 revs. trail from Esko Lyytinen's model plot and leave the 9,
10 & 11 trails only. This combined with the early time for the peak (and
broadness of the top, which indeed would be in line with a composite of 3 peaks
very close to each other like the 9, 10 & 11 rev. trails) made me wonder why
indeed the peak could not be the composite 9, 10 & 11 trails instead of the 4
revs. trail. If both the 4 rev. and the combi 9, 10 & 11 trails would have been
present, there should be a clear double peak with a dip where in my admittedly
very preliminary profile is a peak. At any rate, the 4 revs trail came out
smaller in rates than predicted, so something is fishy about the assumption
that the major peak must be due to the 4 revs. trail with a reasoning "because
that's how it should be according to the models".
I provide this alternative interpretation in the hope it keeps people sharp.
The models have done great, no doubt. But we should seriously discuss which
peak is what trail, while it seems that so far it is merely ASSUMED that the
major peak over Asia 'of course' would have been due to the 4 revs trail. Given
that there were several trails close in time, I think that assumption is open
to debate. It is at least clear that the 4 revs trail came out less rich as
predicted, several thousand less actually. It is very well possible that it was
present at the predicted location but contributed merely a few hundred while
the 9,10 & 11 trails combined contributed the majority of activity. At least I
feel that cannot be ruled out yet.
But more work is needed anyway, so let's see how things look when IMO publishes
it's final analysis of this year's Leonids. Still, I've made up my mind. This
year the 7 revs trail behaved much as predicted, so good chance it will do so
too in 2002.
- Marco Langbroek
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