Prediction tests by using ISF method for the geomagnetic disturbances

A so-called ISF method for predicting geomagnetic disturbances caused by solar wind storm blowing to the earth is suggested. The method is based on a combined approach to solar activity, interplanetary scintillation (IPS) and geomagnetic disturbance observations in 1966–1982, dynamics of disturbance propagation and fuzzy mathematics. Prediction test has been made for 24 large geomagnetic disturbance events that produced space disasters during the period of 1980–1998, with the three-dimensional propagation characteristics, the best close degree of each radio source and the influence of the south-north components of interplanetary magnetic fields considered. The main results are (i) for onset time of the geomagnetic disturbance, events with relative error ΔT _pred/T _obs≤10% between the observation T _obs and the prediction T _pred, account for 45.8% of all events, ≤30% for 78.3% and >30% for only 21.7%; (ii) as for the magnetic disturbance magnitude, events with relative error ΔΣK _p.pred/ΣK _p.obs≤10% between the observation ΣK _p.obs and the prediction ΣK _p.pred, account for 41.6% of all events, ≤30% for 79% and ≤45% for 100%. For example, the prediction test of April–May event in 1998 indicates that ΔT _pred/T _obs=7.4%, ΔΣK _p.pred/ΣK _p.obs=15.3%. Our result shows that the prediction method suggested in this paper has encouraging prospects in improving geomagnetic disturbance prediction in space weather events.