Abstract
A large number of ionograms recorded at Arecibo have been converted to electron density profiles. It is shown that the method of analysis can give very high accuracy for a single layer, but the presence of an E layer can result in systematic errors in the shape of the F layer. Backscatter observations taken at the same times as the ionograms have been analyzed to give electron density curves with a height resolution of 9 km. Although there is a wide range of variation in the shape and height of the ionospheric layers, there is in general close agreement between the profiles obtained by the two methods.