宇宙线变化特征在强地磁暴预报中的应用

利用宇宙线中子探测数据定性分析了地面宇宙线多台站之间的相互联系以及大磁暴与宇宙线之间的响应关系. 以Irkutsk和Oulu宇宙线台站为例, 运用小波去噪技术提高数据的稳定性. 结果表明, 相同世界时条件下, 两站宇宙线通量相关性在事件发生时较高; 而相同地方时条件下, 相关性则在平静期较高. 进一步采用相同地方时条件对不同宇宙线台站的通量在平静期和扰动期的相对变化进行分析, 选取2004年7月强地磁暴典型事例进行直观分析, 发现大地磁暴前Irkutsk和Oulu台站的宇宙线相对通量发生明显差异, 可以尝试作为强地磁暴宇宙线先兆特征. 通过对2001年3月至2005年5月的强磁暴和中强磁暴进行统计, 得到与强地磁暴相关的适当宇宙线相对差异阈值. 将得到的阈值对2005年9月至2011年12月所有强磁暴及中强磁暴进行验证, 总成功率达到87.5%, 误报率为35.7%, 结果较好. 

Application in Predicting the Geomagnetic Storm with Variation Characteristics of Cosmic Ray

An algorithm is introduced to use the cosmic ray neutron detector data to predict great geomagnetic storms. The connection between cosmic ray and great geomagnetic storms and the relationship between cosmic ray stations are qualitatively analyzed. The neutron detector data from Irkutsk and Oulu stations are employed and wavelet denoising technology is used to improve the stability of the data. It is found that under the same conditions of universal time the correlation of the two stations is higher than quiet days during geomagnetic disturbances, while it is contrary under the same local time. Thus the variation in disturbed time and quiet time can be used to predict geomagnetic storms. The algorithm is specifically used to analyze the geomagnetic storm events in July 2004. It is found that before geomagnetic storm, relative fluxes of cosmic rays of Irkutsk and Oulu station became different. It can be used as a precursor of strong geomagnetic storms. Statistics with all relative events during March 2001 to May 2005 support an appropriate threshold related to the relative difference of cosmic ray about strong geomagnetic storms. It is tested with all events during September 2005 to December 2011 with the threshold. The result turned out to be encouraging with the accuracy rate reaching 87.5% (7 out of 8) and false forecast rate reaching 35.7% (5 out of 14).