The ionosphere shows a large degree of variability on time scales from hour
s to the solar cycle length. This variation is associated with magnetospher
ic storms, the Earth's rotation, the season, and the level of solar activit
y. To make accurate predictions of key ionospheric parameters all. these va
riations must be considered. Neural networks, which are data driven non-lin
ear models, are very useful for such tasks. In this work we examine if the
F2 layer plasma frequency, foF2, at a single ionospheric station can be pre
dicted 1 to 24 hours in advance by using information of past foF2 observati
ons, magnetospheric activity, and time as inputs to neural networks. Partic
ular attention has been paid to periods when great geomagnetic storms were
in progress with the aim to develop a successful ionospheric storm forecast
ing tool. (C) 2000 Elsevier Science Ltd. All rights reserved