日冕物质抛射引起地磁扰动的分类预报

对1997—2003年期间引起地磁扰动的72个加速日冕物质抛射(CME)事件和69个减速CME事件进行了特性分析，并针对经行星际闪烁(IPS)认证的32个加速CME引起的地磁扰动事件和32个减速CME引起的地磁扰动事件分类建立了新的从属函数μ_T和新的磁扰开始时间修正项, 经验证预报效果得到显著提高.对于加速CME引起的地磁扰动事件，磁扰开始时间的预报值T_pre与观测值T_obs比较，相对误差ΔT_pre/T_obs≤10%的事件占总事件数的21.86%；ΔT_pre/T_obs≤30%的事件为78.13%；而ΔT_pre/T_obs>50%的事件为9.36%；对于减速CME引起的地磁扰动事件相对误差ΔT_pre/T_obs≤10%的事件占总事件数的25.00%；ΔT_pre/T_obs≤30%的事件为84.37%；而ΔT_pre/T_obs>50%的事件仅为3.13%.这表明该预报方法对空间灾害性事件的磁扰动的定量预报具有很大的现实可能性. 关键词： 日冕物质抛射 地磁扰动 从属函数

Classified prediction of geomagnetic disturbance caused by coronal mass ejection

The characteristics of accelerating coronal mass ejection (CME) and decelerating CME happening during 1997—2003 are analyzed. Prediction tests are made for geomagnetic disturbance events caused by the gradually accelerating CME-associated interplanetary shock waves and the decelerating CME-associated interplanetary shock waves, which can be identified by interplanetary scintillation (IPS) observation during 1997—2003. New membership functions and new correctional item of onset time of geomagnetic disturbances are respectively constituted for two kinds of CME. The main results are: for the onset time of the geomagnetic disturbance in the accelerating CME, the relative error between the observation,T_obs, and the prediction,T_pre,ΔT_pre/T_obs≤10% for 21.86% of all events, ≤30% for 78.13% and ≥50% for only 9.36%; for the decelerating CME, ΔT_pre/T_obs≤10% for 25.00% of all events, ≤30% for 84.37% and ≥50% for only 3.13%.These results show that the method has good feasibility for the geomagnetic disturbance predictions.