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.