HR: 0800h
AN: SH51D-0295    [Abstracts]
TI: Power Fluctuations in Meteor Head Echoes Observed with the EISCAT VHF Radar
AU: Kero, J
EM: kero@irf.se
AF: Swedish Institute of Space Physics, P.O. Box 812, Kiruna, SE-981 28 Sweden
AU: Szasz, C
EM: csilla@irf.se
AF: Swedish Institute of Space Physics, P.O. Box 812, Kiruna, SE-981 28 Sweden
AU: * Pellinen-Wannberg, A
EM: asta@irf.se
AF: Swedish Institute of Space Physics, P.O. Box 812, Kiruna, SE-981 28 Sweden
AU: Wannberg, G
EM: gudmund@eiscat.com
AF: EISCAT Scientific Association, P.O. Box 164, Kiruna, SE-981 23 Sweden
AU: Westman, A
EM: assar@eiscat.com
AF: EISCAT Scientific Association, P.O. Box 164, Kiruna, SE-981 23 Sweden
AB: Meteor head echoes are radio wave reflections from the plasma generated by the interaction of meteoroids with the atmosphere at about 80-120 km altitude. The echoes are characterized by being transient and Doppler shifted. The received power is confined in range, as from a point source, and it moves with the line-of-sight velocity of the meteoroid. Head echoes arise and disappear as meteoroids pass through the radar beam, and usually last from one tenth to a few tenths of a second. Some meteor echoes in the data from a meteor experiment carried out with the EISCAT VHF radar at 224 MHz contain peculiar pulsations in received power. These pulsations are in the frequency range 50-100 Hz. The interpulse period of the experiment was 2.167 ms, i.e., meteoroid line-of-sight velocity and echo power was monitored at 461 Hz. This limits the observable power fluctuation frequency range to about 10-230 Hz. The process causing the echo power pulsations is at present not identified. Plasma effects are the most likely cause, a presumable mechanism is for instance asymmetrical dust grains in rotation causing a modulation of the ionization rate.
DE: 6015 Dust
DE: 6213 Dust
DE: 6245 Meteors
DE: 6999 General or miscellaneous
DE: 2129 Interplanetary dust
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting