A correlation between extended intervals of ULF wave power and storm-time geosynchronous relativistic electron flux enhancements

Recent research has highlighted the possibility that large-amplitude ULF pulsations may act as an acceleration mechanism for generating relativistic electron populations in the outer zone magnetosphere during storm-time. We examine solar wind characteristics, Pc5 ULF wave power and outer magnetospheric measurements of high energy electron flux during the recurrent fast solar wind speed streams which occurred during the first half of 1995. We find a close correlation between extended intervals of significant pulsation power and observations of enhanced relativistic (>2 MeV) electron flux in the outer zone magnetosphere, suggesting that these two features may be causally related. We demonstrate that significant electron flux increases at geosynchronous orbit are only observed in response to ULF wave power which is sustained at high levels over a number of days following storm onset. Our observations suggest that ULF pulsations may be the likely acceleration mechanism for generating storm-time MeV killer electrons in the magnetosphere.