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(meteorobs) Comments on the Y2K Leonids from Esko Lyytinen

    Here is an e-mail message that I have just received from Esko Lyytinen 
concerning the 2000 Leonids and their possible impact concerning future 
predictions for 2001 and 2002.  If you have any specific questions for him, 
his e-mail address is: esko.lyytinen@minedu.fi

-- joe 

-----------------------------------------------------
    Joe Rao,

    Thank you for forwarding this and some earlier discussions etc. 
    I am planning to write some of my thoughts into IMO-news and
possibly other email-lists. This may take some time, because of more than
typical email correspondence and following of information and some checks
with modeling and the work, I do for my living (other than astronomy).

    Quite shortly to you, I am quite satisfied with the success of these
predictions. There were some surprises (some surprises were expected),
mainly the extended duration of 8 and 4 rev. trail encounters, even though
some lengthening of the 8 rev. trail outburst was expected. It now (after
some quick modeling) appears, as if bigger than expected "A2 effect" would
be the (main) cause and this would also seem to explaint the increased rates
before the predicted maximum times (maybe as separate peaks around 02UT and
07UT, as suggested by some of the data). This A2 effect seems to have been
around the maximum possible for these particles (for the size of particles
by the "seasonal Yarkovsky effect"). In my EM&P paper, there is a mention of
bigger than expected A2 effect, suggested by timing of the distant 1999 4
rev. trail encountern. Then only some possible future study was considered,
even though some additional checks could have been made for this year,
giving at least somewhat better profiles for the outbursts. (Maybe I was not
enough convinced myself of that mention, untill now.)

    Ii is my opinion, that this MAY mean somewhat lower rates than
predicted for the 2001 and 2002 storms, especially for the old ones, but not
necessary. There could be an inner  "core" in the trails with different
physical properties for the particles. 
    In any case, I now expect a good storm for the 4 rev. encounter in
2001 and other good outbursts around the storm limit. 
    (Some further modeling for example will be needed, what does it
mean, IF the particles even in the core do have a bigger than the earlier
expected A2 effect.)
    I don't yet know, if we will (with Tom) give new values for 2001 and
2002, or not. Tom has now been in then Pacific area to find a good site for
the planned 2001 Leonid expedition and also in Australia for future solar
eclipse expediton, so I have had only a minimum of discussions with him
after the outbursts. I am also waiting for final analysis of the
observations etc.

    Best Wishes, Esko

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