关于狮子座流星雨预报中的FM（FMD）

http://feraj.narod.ru/Radiants/Predictions/1901-2100eng/Leo2001-2010eng.html

在这份Mikhail Maslov发布的狮子座流星雨预报中有个FM（FMD）值，我不是很明白。写信给他咨询了，回复如下。请各位同好帮忙看看 PS：我还是不太懂

this parameter primarily shows the strength of the outburst, not
its duration. Expected ZHR is in direct proportion to absolute value
of fM(fMD).
I calculate fM(fMD) basing on the difference between moments of
passing their points of minimal distances to the Earth's orbit (MD) of two
particles with ejection velocities differing by one computation step (0.1 m/c,
0.01 m/s, for example, 4.2 and 4.3 m/s). I said basing as this
temporal difference is the main factor for fM(fMD), but also such
values as difference between rD-rE for these particles and difference
between solar longitudes of their MD points are taken into account.
Normally their contributions are neglibly small, but under some
conditions they can become more substantial.

Speaking of negative fM(fMD) values - they come when the trail
is reversed, i.e. particles with higher ejection velocities pass their
MD points earlier than particles with lower ejection velocities. In
this case the temporal difference for, say, particles with ejection
velocities of 4.2 and 4.3 m/s is negative, so the whole fM(fMD) value
turns to be negative.

Don't hesitate to ask if you feel something is still not fully understood.

Best regards, Mikhail.