On the Modes of Diffuse Spreading of Ionized Meteor Trails

A special regime of the lower ionosphere sounding at altitudes of about 100 km reveals radio reflections from fairly dense (with a line density of 10¹⁴–10¹⁶ m^–1) ionized meteor trails with a characteristic lifetime from a few tens of seconds to several tens of minutes. During the first 250 s, radio reflections from ionized trails with a line density of (2–3) × 10¹⁵ m^–1 exhibit a power-law time dependence of the frequency of the reflected radio signal, $f\propto t^{-\gamma }$, with γ = 0.5 (classical diffusion mode). Less dense trails decay more slowly (γ < 0.5, subdiffusion mode), while denser ones decay faster (γ > 0.5, superdiffusion mode). It is shown that different modes of diffuse spreading of meteor trails can be caused by the high inhomogeneity of the medium and depend on the scale of ionized trails arising upon destruction of meteoroids.