Application of close degree to classified prediction of geomagnetic disturbances

Using the close degree and membership function and comprehensive evaluation in fuzzy mathematics, in conjunction with the solar observation of CME and IPS observation for the interplanetary solar storms caused by CME, we present a close degree prediction method for geomagnetic disturbance events caused by coronal mass ejection (CME)-shock waves identified by IPS observation. Based on the analysis of 74 geomagnetic disturbance events caused by CME- shock waves identified by IPS observation during 1997-2003, five clustering indexes and their weighted fuzzy sets are constructed. Typical fuzzy sets of small, moderate, and intense geomagnetic disturbance events are built based on comprehensive evaluation. By constructing the respective fuzzy set of each event, based on the close degree between the fuzzy set and typical fuzzy sets, the prediction for different geomagnetic disturbance caused by the events can be made. Main results are as follows: For the 74 geomagnetic disturbance events, the prediction accuracy is 53.3% for small geomagnetic disturbance; 100% for moderate geomagnetic disturbance; and 90.20% for intense geomagnetic disturbance. The average precision of this method is 84%. This method is an effective application of fuzzy mathematics to studying the geomagnetic disturbance.