HR: 11:40h
AN: SA41C-06    [PDF]
TI: A Semi-Annual Study of the Micrometeor Influx in the Mesopause
AU: * Janches, D
EM: djanches@naic.edu
AF: Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612 United States
AU: Nolan, M C
EM: nolan@naic.edu
AF: Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612 United States
AU: Mathews, J D
EM: jdmathews@psu.edu
AF: Penn State University, 121 EE East, University Park, PA 16802 United States
AU: Meisel, D D
EM: meisel@geneseo.edu
AF: SUNY-Geneseo, 1 College Circle, Geneseo, NY 14454 United States
AB: We present and discuss results from the first six months of a year-long observation campaign of the micrometeor influx in the upper atmosphere using the dual-beam 430 MHz Arecibo Observatory radar. The AO radar detects decelerating particles in the size range 0.5-100 microns for which precise altitude; instantaneous Doppler velocity (rms errors of the order of 10-100 m/sec) and (constant) deceleration are obtained. This provides a tool for the study of a mass-region of the interplanetary dust distribution and its influence to the mesopause that was previously inaccessible to ground-based instruments and helps bridge the gap between spacecraft dust measurements and traditional meteor radar capabilities. The meteor rate detected inside the 305 m-diameter radar beam peaks at sunrise ($\sim$40 events per minute) when the radar points near the apex. We find the meteor flux rate as well as the geocentric velocity distribution to be strongly dependent on the topocentric declination implying a function with radiant ecliptic latitude. In addition, we present estimations of the total micrometeor mass flux derived from these observations, resulting in $\sim$2000 tons of meteoric material deposited over the whole earth each year in the 80-120 km altitude region. Preliminary results also show that the mass flux peaks in June (i.e. a function of ecliptic longitude) in agreement with diurnal measurements of metallic densities derived from lidar observations.
DE: 0340 Middle atmosphere--composition and chemistry
DE: 2129 Interplanetary dust
DE: 5405 Atmospheres--composition and chemistry
DE: 6213 Dust
DE: 6245 Meteors
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting