A method for foF2 short-term prediction

A method for foF2 short-term prediction with 1-24 hour lead times is propos ed. It is based on Delta foF2 (deviation of hourly foF2 from running median ) regression with the previous Delta foF2 observations and hourly spline-in terpolated daily Ap index. An optimum training time interval of 25-30 days, which is close to one solar rotation, has been revealed. The effect of Ap index inclusion is seen only for large (more than 3 hours) lead time predic tion. The prediction accuracy was shown to depend on Ap/foF2 time shift int erval, the latter being dependent on local time of the storm onset and this may be taken into account in the prediction method. For quiet and moderate disturbed conditions the basic method provides foF2 forecast with relative mean deviation of 8-13% which is acceptable from practical point of view. A version of the basic method is proposed to predict foF2 during severe sto rm periods. This modified method in comparison with the basic one and the W renn's et at, (1987) approach was shown to provide the best prediction accu racy and may be recommended for practical use. (C) 2000 Elsevier Science Lt d. All rights reserved.