行星际南向磁场事件与强磁暴

摘要

The relationship between IMF B{ s events(Bs>10 nT, VBs>5 mV/m and both last more than 3 h)and intense magnetic storms (Dst -100 nT) is analyzed using the solar windand geomagnetic data from 1978-1988. The results show that one hundredpercent of Bs events can cause magnetic storms, but only 84% are intensestorms. Although all the intense magnetic storms correlate to larger IMF Bs closely, only 68% of intense magnetic storms are actually caused byBs events. The relationship between Bs events and intensemagnetic storms is not in correspondence of one to one. The effects ofmagnetospheric background and fluctuations of Bs on the causeof magnetic storms must be taken into account. Also the attention shouldbe paid to the fact that Dst indicesare affected by many electric current systems after than ring current.%利用1978-1988年期间的太阳风和地磁资料对行星际磁场(IMF)南向分量Bs事件(即Bs>10 nT及其所驱动的昏向电场VBs>5 mV/m、持续时间 T>3 h的事件)与强磁暴(Dst -100 nT)关系进行了分析.结果表明,100%的Bs事件都能引起磁暴的发生,但其中只有84%为强磁暴;强磁暴的发生都与较强的IMF Bs活动密切相关,但只有68%的强磁暴伴随Bs事件而发生; Bs事件与强磁暴并不是一一对应的关系.在分析太阳风与磁层的相互作用引起磁暴时,还必须考虑磁层背景情况和Bs波动对磁暴形成的贡献;同时应注意Dst指数会受到环电流以外的诸多电流体系等因素的影响这一事实.