[Aavso-sid-list] Meteor Storms and Possible VLF Effects ?

[Thomas Ashcraft]

Hi Rodney,

The interesting thing about the paper that I referred to is that it 
addresses the effects of a possible full meteor swarm (or storm) on the 
ionosphere rather than the capture of individual meteors at ELF/VLF.  
Maybe there are ionospheric disturbances that SID observers record that 
are actually sporadic meteor swarms.   ??

Thomas

Rodney Howe wrote:
> It seems most of the SID work at VLF frequencies is done at 
> integration times of minutes or at most 1 second intervals.  Would it 
> be easier to detect meteors with an ELF receiver?  Would you need to 
> capture meteor emissions with sound cards or high data capture rates?
>
> Here's an ELF radio which might work:
> http://home.flash.net/~evogel/natrad2.pdf
>
> Also, will it be difficult to discriminate Sprites from meteors?  A 
> lot of work has been done on Sprites at both ELF and VLF
> http://elf.gi.alaska.edu/spr20010406.html
> http://www.sgo.fi/~fredrik/publications/SpritesSearch.html
>
> Rodney
>
>
> Here's more ELF and VLF work.
> http://elf.gi.alaska.edu/fagu98.html
>
>
> ----- Original Message ----- From: "Thomas Ashcraft" 
> <ashcraft at heliotown.com>
> To: <aavso-sid-list at aavso.org>
> Sent: Sunday, February 17, 2008 11:04 AM
> Subject: Re: [Aavso-sid-list] Meteor Storms and Possible VLF Effects ?
>
>
> For those interested in this article for their own personal research I
> can email it as a .pdf file. But it cannot be posted on the web publicly
> due to copyright concerns. For personal research only please.
>
> You can email me at    :  ashcraft(at)heliotown.com
>
> Thomas Ashcraft wrote:
>> Have any SID observers here connected any observations to meteor storms?
>>
>> 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.
>>
>