The Interpretation of Some Observations of Radio Waves Scattered from the Lower Ionosphere

Abstract

Possible shapes and spatial scales of ionospheric irregularities in the lower ionosphere have been determined from analyses of two sets of radio wave back-scattering observations: measurements of the spatial scale of the ground pattern of the wave field back-scattered from altitudes near 95 km and measurements of the amount and angular distribution of power back-scattered from solitary horizontally-moving irregularities at altitudes near 75 km. At 95 km the irregularities are anisotropic, with larger horizontal than vertical dimensions. For an assumed Gaussian distribution of ionization, the inferred axial ratio (horizontal to vertical) is about three. It is tentatively concluded that the irregularities at 75 km are sharply bounded and are some kilometres in horizontal extent.