Prediction Method of CME Associated Geomagnetic Disturbances Based on Fuzzy Mathematics

Based on the 73 geomagnetic disturbance events caused by coronal mass ejection （CME） associated with interplanetary shock waves and using fuzzy mathematics, here is presented a prediction method for geomagnetic disturbances. According to the solar location of CME, the transit time of the interplanetary disturbance, the geomagnetic disturbance magnitude and the velocity jump observed by IPS at the disturbed front, five membership functions μθ,μT,μM,μ△v are constituted. Based on the five membership functions and fuzzy mathematics, prediction tests for the 73 CME associated geomagnetic disturbance events during 1996--2004 are made by considering the influence of CME velocity on the onset time of geomagnetic disturbances. Main results are： （1） For the prediction of the magnetic disturbance onset time, 91.78% is within the range of relative error △Tpre/Tos≤30% and 12.33% within △Tpre/Tos≤30%; （2） For the prediction of the geomagnetic disturbance amolitudes, 60.27% is within the range of relative error △∑Kp/∑Kpobs≤30% and 12.33% within △∑Kp/∑Kpobs≤50%. These results show that the prediction method has good feasibility for geomagnetic disturbance prediction.