Previous reports suggest that north/south interplanetary magnetic field (IMF) turnings are the predominant cause of north/south fluctuations in dayside equatorial ground magnetograms. We compare 210¿ Magnetic Meridian (MM) ground magnetograms with simultaneous IMP 8 solar wind and LANL geosynchronous energetic electron observations during 1993 and 1994 to search for this effect. About one third of the northward equatorial magnetic field enhancements can be associated with increases in the solar wind dynamic pressure, a second third with substorm onset as measured by energetic electron injections, and the final third with southward IMF turnings. An alternative explanation can be found for most enhancements associated with north/south IMF variations but not for enhancements associated with solar wind dynamic pressure variations or substorm onsets. Our results suggest that dayside equatorial ground magnetograms may be used to monitor both solar wind dynamic pressure variations and nightside substorm onsets. ¿ 1998 American Geophysical Union