A method for foF2 short-term prediction

A method for foF2 short-term prediction with 1–24 hour lead times is proposed. It is based on ΔfoF2 (deviation of hourly foF2 from running median) regression with the previous ΔfoF2 observations and hourly spline-interpolated 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 prediction. The prediction accuracy was shown to depend on Ap/foF2 time shift interval, 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 storm periods. This modified method in comparison with the basic one and the Wrenn's et al., (1987) approach was shown to provide the best prediction accuracy and may be recommended for practical use.