(meteorobs) Meteors and VLF article abstract

[Thomas Ashcraft]

For those interested in the possible connection between meteors and VLF 
effects:

Here is the abstract of a paper published in Science. Sorry, I don't 
know how to retrieve the full paper. I do remember reading this article 
many years ago and questioning the results that the researchers arrived at.

- Thomas Ashcraft

*********

http://www.sciencemag.org/cgi/content/abstract/246/4931/787?ck=nck

/Science/ 10 November 1989:
Vol. 246. no. 4931, pp. 787 - 790
DOI: 10.1126/science.246.4931.787


Articles


Effects of the Large June 1975 Meteoroid Storm on Earth's Ionosphere

*P. Kaufmann ^1 , V. L. R. Kuntz ^1 , N. M. Paes Leme ^1 , L. R. Piazza 
^1 , J. W. S. Vilas Boas ^1 , K. Brecher ^2 , and J. Crouchley ^3 *

^1 Centro de Ráadio-Astronomia e Aplicacäes Espaciais-CRAAE, Escola 
Politécnica, Universidade de São Paulo, C. P. 8174, 05508—São Paulo, Brazil
^2 Department of Astronomy, Boston University, Boston, MA 02215
^3 Department of Physics, University of Queensland, St. Lucia, 
Queensland 4067, Australia

The June 1975 meteoroid storm detected on the moon by the Apollo^ 
seismometers was the largest ever observed. Reexamination of^ radio data 
taken at that time showed that the storm also produced^ pronounced 
disturbances on Earth, which were recorded as unique^ phase anomalies on 
very low frequency (VLF) radio propagation^ paths in the low terrestrial 
ionosphere. Persistent effects^ were observed for the major storm period 
(20 to 30 June 1975),^ including reductions in the diurnal phase 
variation, advances^ in the nighttime and daytime phase levels, and 
reductions in^ the sunset phase delay rate. Large nighttime phase 
advances,^ lasting a few hours, were detected on some days at all VLF 
transmissions,^ and for the shorter propagation path they were 
comparable to^ solar Lyman alpha daytime ionization. Ion production 
rates attributable^ to the meteor storm were estimated to be about 0.6 
to 3.0 ions^ per centimeter cubed per second at the E and D regions, 
respectively.^ The storm was a sporadic one with a radiant (that is, the 
point^ of apparent origin in the sky) located in the Southern 
Hemisphere,^ with a right ascension 1 to 2 hours larger than the sun's 
right^ ascension.