Diurnal variation of non-specular meteor trails

Abstract

We present results of simulated radar observations of meteor trails in an effort to show how non-specular meteor trails are expected to vary as a function of a number of key atmospheric, ionospheric and meteoroid parameters. This paper identifies which geophysical sources effect the variability in non-specular trail radar observations, and provides an approach that uses some of these parameter dependencies to determine meteoroid and atmospheric properties based upon the radar meteor observations. The numerical model used follows meteor evolution from ablation and ionization to head echo plasma generation and through formation of field aligned irregularities (FAI). Our main finding is that non-specular meteor trail duration is highly sensitive to the presence of lower thermospheric winds or electric fields and the background ionospheric electron density. In an effort to make key predictions we present the first results of how the same meteoroid is expected to produce dramatically different meteor trails as a function of location and local time. For example, we show that mid-latitude trail durations are often shorter lasting than equatorial trail observations because of the difference in mid-latitude wind speed and equatorial drift speed. The simulated trails also account for observations showing that equatorial nighttime non-specular meteor trails last significantly longer and are observed more often than daytime trails.