Lidar observations of Fe and Na meteor trails with high temporal resolution

Extensive lidar measurements of Fe and Na meteor trails were conducted with an integration period of 3.2 S. A total of 155 Fe trails and 136 Na trails were registered, respectively, from the 260-h Fe and 320-h Na photon count profiles. They came from the observations that did not coincide with the major meteor showers and thus represent sporadic meteors. The mean input fluxes from the lidar meteor trail measurements are 1.5 x 10(5) atom cm(-2) s(-1) for Fe and 1.4 x 10(4) atom cm(-2) s(-1) for Na. The values might be temperate overestimates of the absolute lower bounds of the mean Na and Fe input fluxes when wind is advecting the metal vapor trails, because strong winds along with small-scale turbulence and shear could distort and dilute the trails, consequently shortening their lifetime. The trail altitude distribution for each metal species differs in details from the corresponding background layer, whereas the centroid height for each trail distribution approaches that of the relevant background layer (similar to 90.9 km for Na trails and 89.1 km for Fe trails). Only 8 two-element trails are detected from a total of 210-h simultaneous and common-volume Na and Fe lidar measurements. The observed two-element meteor trails yield the mean Fe/Na abundance ratio of similar to 9.0. These trail features suggest a role of differential ablation. (C) 2011 Elsevier Ltd. All rights reserved.