Meteor Induced Ridge and Trough Formation and Structuring of the Nighttime E-Region Ionosphere

A meteoroid penetrating the Earth's atmosphere leaves behind a trail of dense plasma embedded in the E-region ionosphere. As the trail diffuses into the background plasma, large ambipolar electric fields develop. These fields are strongest perpendicular to the Earth's geomagnetic field (ěc B) and generally extend many kilometers along ěc B before gradually diminishing in amplitude. Away from the trail, this same field will cause plasma to collect into a long ridge extending along ěc B, enhancing the density by as much as a factor of 2. The field will also dig out density depressions on each side of the ridge, removing up to 90% of the plasma. We predict that meteor-induced, large-amplitude, density perturbations may fill as much as 20% of the ionosphere between 95 and 120 km altitude. This paper will present finite-element simulations and theory to show how meteors produce plasma ridges and troughs. We will estimate the extent of these as a function of altitude and meteor density. Finally, we will estimate the importance of these to the nighttime E-region density profile, a previous unexplained feature of the E-region, measured by rockets