Meteor fluxes and visual magnitudes from EISCAT radar event rates: a comparison with cross-section based magnitude estimates and optical data

Abstract

Abstract. Incoherent scatter radars (ISR) are versatile instruments for continuous monitoring of ionisation processes in the Earth's atmosphere. EISCAT, The European Incoherent Scatter facility has proven eective also in meteor studies. The time resolution of the radar can be reduced to a few milliseconds, sucient to resolve the passage of individual meteors through the narrow ISR beam. Methods for group and phase velocity determination of the meteoroids and the discrepancy between the results related to the target behaviour are presented. The radar cross sections of echoes associated with moving meteoroids (``meteor head echoes'') are very small and increase with decreasing wavelength. The parent meteoroids are found to have visual magnitudes far below the detection limit of most optical observations. The equivalent visual magnitude limit of the smallest objects observed by EISCAT in the current experiments has been estimated by two dierent methods, both from the cross-section measurements and from the measured event rates. Both methods give a limit value of +10 for the smallest objects while the upper limit is +4. The lower limit of the visual magnitude for the collocated optical measurement system is +4. Thus the two detection systems observe two dierent meteor size ranges, with the radar almost reaching micrometeorite population. Meteor¯uxes estimated from the event rates and the radar system parameters agree well with previous extrapolated values for this size range.

Modelling high-power large-aperture radar meteor trails

“…We use the resulting line-density (electrons per meter along the meteor's path) to estimate where the radar would measure a head echo (Close et al, 2002;Janches et al, 2000;Pellinen-Wannberg et al, 1998;Mathews et al, 1997). We make an additional crude approximation for the scattering strength of the head echo shown in Fig.…”

Meteor-head echo observations using an antenna compression approach with the 450MHz Poker Flat Incoherent Scatter Radar

“…Since mid 1990s extensive meteor-head echo observations have been performed with different High-Power Large-Aperture Radars (HPLARs) (e.g., Janches et al, 2000;Pellinen-Wannberg et al, 1998;Sato et al, 2000;Close et al, 2002;Chau and Woodman, 2004). Most of these observations are characterized by the use of very narrow beams (less than 2 half-power full beam widths).…”

Simultaneous optical and radar measurements of meteors using the Poker Flat Incoherent Scatter Radar

“…There are, however, disproportionately less studies that combine multiple observational techniques. The combining of radar measurements and optical observations has been used in the past in order to gain insight into meteor ablation physics (Mathews et al, 2010;Brosch et al, 2004;Fujiwara et al, 1995;Pellinen-Wannberg et al, 1998;Szasz et al, 2008). Such a specific comparison has not yet been done with the Poker Flat Incoherent Scatter Radar (PFISR).…”