CME地磁扰动事件的模糊预报方法

Prediction Method of CME Associated Geomagnetic Disturbances Based on Fuzzy Mathematics

以1997—2003年期间的73个日冕物质抛射(CME)激波扰动事件和模糊数学为基础,提出了一种预报地磁扰动的方法.该方法以CME事件爆发的日面经纬度、相关地磁扰动事件的渡越时间、地磁扰动指数、IPS观测的太阳风速度跃变量为基础,建立了预报CME地磁扰动事件的μ_θ,μ_(?),μ_T,μ_M,μ_(Δv)从属函数,考虑了CME初始速度对激波到达时间的影响.以这5个从属函数为基础并利用模糊数学对1996—2004年期间73个经行星际闪烁(IPS)观测认证的CME激波引起的地磁扰动事件进行了预报实验.实验结果表明,磁扰开始时间预报的相对误差,ΔT_(pre)/T_(obs)≤30%的事件占总事件数的91.78%,而ΔT_(pre)/T_(obs)>30%的事件占总事件数的12.33%;磁扰幅度(∑Kp)大小的预报,其相对误差Δ∑Kp/∑Kp_(obs)≤30%的事件占总事件数的60.27%,相对误差≥50%的事件占总事件数的12.33%.这表明该预报方法对空间灾害性事件地磁扰动的定量预报具有很大应用潜力.

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.