Prediction tests by using “ISF” method for the geomagnetic disturbances

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Prediction tests by using “ISF” method for the geomagnetic disturbances

Wei, Fengsi / Feng, Xueshang / Ya, Xu / Fan, Quanlin

AbstractA so-called “ISF” prediction method for geomagnetic disturbances caused by solar wind storms blowing to the Earth is suggested. The method is based on a combined approach of solar activity, interplanetary scintillation (I) and geomagnetic disturbance observations during the period 1966–1982 together with the dynamics of solar wind storm propagation (S) and fuzzy mathematics (F). It has been used for prediction tests for 37 geomagnetic disturbance events during the descending solar activity phase 1984–1985, and was presented in 33rd COSPAR conference. Here, it has been improved by consideration of the three dimensional propagation characteristics of each event, the search for the best radio source and the influence of the southward components of interplanetary magnetic fields on the geomagnetic disturbances. It is used for prediction tests for 24 larger geomagnetic disturbance events that produced space anomalies during the period 1980–1999. The main results are: (1) for the onset time of the geomagnetic disturbance, the relative error between the observation, Tobs, and the prediction, Tpred, ΔTpred/Tobs⩽10% for 45.8% of all events, ⩽30% for 78.3% and >30% for only 21.7%; (2) for the magnetic disturbance magnitude, the relative error between the observation, ∑Kp,obs, and the prediction, ∑Kp,pred, Δ∑Kp,pred/∑Kp,obs⩽10% for 41.6% of all events, ⩽30% for 79% and ⩽45% for 100%. This shows that the prediction method described here has encouraging prospects for improving predictions of large geomagnetic disturbances in space weather events.