Inferring the global cosmic dust influx to the Earth’s atmosphere from lidar observations of the vertical flux of mesospheric Na

Estimates of the global in fl ux of cosmic dust are highly uncertain, ranging from 0.4 – 110 t/d. All

meteoric debris that enters the Earth ’ s atmosphere is eventually transported to the surface. The downward

fl uxes of meteoric metals like mesospheric Na and Fe, in the region below where they are vaporized and

where the majority of these species are still in atomic form, are equal to their meteoric ablation in fl uxes,

which in turn, are proportional to the total cosmic dust in fl ux. Doppler lidar measurements of mesospheric Na

fl uxes made throughout the year at the Star fi re Optical Range, New Mexico, (35°N) are combined with the

Whole Atmosphere Community Climate Model predictions of the relative geographic variations of the key

wave-induced vertical transport processes to infer the global in fl uxes of Na vapor and cosmic dust. The global 2

mean Na in fl ux is estimated to be 16,100 ± 3200 atoms/cm /s, which corresponds to 278 ± 54 kg/d for the global input of Na vapor and 60 ± 16 t/d for the global in fl ux of cosmic dust.