Accuracy of the CCIR F2 layer model at low and middle latitudes

The accuracy of the foF2 and hmF2 maps derived from the CCIR ionospheric model is investigated in various ways, including comparisons with airglow data from satellites, and it is concluded that the maps are generally significantly in error over ocean regions. The procedure followed in constructing the model sometimes causes the errors to extend over neighbouring continents. Methods by which the model may be improved are discussed.