Evidence for sheet‐like auroral ionospheric irregularities

Abstract

A uniquely located, statistically prominant radiowave scintillation enhancement has been identified in nighttime auroral‐zone data. The enhancement occurs whenever the propagation path coincides with an L‐shell in the region of diffuse auroral particle precipitation. It is hypothesized that this enhancement is a purely geometric effect due to sheet‐like ionospheric irregularity structures aligned along L‐shells. This hypothesis is confirmed by spaced‐receiver data showing that the diffraction pattern is elongated along the geomagnetic east‐west direction when the scintillation enhancement occurs.