Do flux transfer events cause long‐period micropulsations in the dayside magnetosphere?

Abstract

Russell and Elphic (1979) suggested the possibility that flux transfer events (FTEs) generate long‐period micropulsations in the outer, dayside magnetosphere. We examine the reasons for this hypothesis and present results of two pulsation surveys designed to test it. In the first survey, observations of micropulsations by GOES 2 are compared with ISEE 3 and IMP observations of interplanetary magnetic field (IMF) direction; since FTEs are highly correlated with southward IMF, we looked for a similar correlation between pulsations and southward IMF. In the second survey a catalogue of ISEE 1 and 2 magnetopause crossings is compared with magnetometer readings from GOES 2 and 3 to determine whether Pc 4 and Pc 5 pulsations are more likely to occur after FTEs have taken place. Our results indicate that there is a correlation between FTEs and transversely polarized Pc 4 pulsations with periods between 60 and 120 s but not between FTEs and Pc pulsations with periods greater than 120 s. This suggests that the generating (or driving) frequency associated with FTEs lies between 60 and 120 s.