[dr_lew]

Well, 10^10 km^2 is (10^5 km)^2 or roughly the "footprint" of the earth. So we're talking about 10^8/14 particles/day or 10^8/14/24 ~= 300000 particles per hour entering the earth's atmosphere, at peak.

Ooops. The earth is roughly (10^4 km)^2, so the flux hitting the earth is 1/100 this, or ~3000 particles/hour ... again, of course, according to my reading.

[Yosemitest]

Check out this data from Kasuo Kinoshita, http://jcometobs.web.fc2.com/ [Orbital elements of the comet 209P LINEAR].
The numbers are beyond my comprehension, but you might can use them.