Diffusion of Plasmas from Ablating Meteoroids in the Ionosphere

摘要

High Power, Large Aperture (HPLA) Radars have been used to characterize the plasmas formed as meteoroids ablate in Earth's atmosphere. These plasmas are referred to as heads, which are the plasmas surrounding the meteoroids, and trails, which are plasmas behind the meteoroids. A particular subset of the trails is nonspecular trails, which are detected when the radar beam is quasi-perpendicular to the magnetic field. These returns are thought to be the reflection from field aligned irregularities (FAIs) that form after the onset of turbulence in the meteor trail. In this paper, we present a case study analysis of a nonspecular trail detected by the Advanced Research Project Agency (ARPA) Long-range Tracking and Identification Radar (ALTAIR). These data include dual frequency, dual polarized, and high range resolution in-phase (I) and quadrature (Q) returns with additional azimuth and elevation data derived from the monopulse system. For the first time, we determine the ambipolar diffusion coefficients for the nonspecular trails and compare these with previous specular trail studies. Second, we use the monopulse angles to determine the position of the plasma trail in order to develop an understanding of the meteor trail diffusion process. Our results demonstrate that the ambipolar diffusion coefficient, though sufficient for a specular trail, may not provide a complete description of the diffusion of a nonspecular trail and that other types of diffusion may need to be considered.