Ionospheric Currents Observed Using the Flux-gate Magnetometer on the C/NOFS Satellite

The instrument suite that comprises Goddard's Vector Electric Field Investigation (VEFI) onboard the C/NOFS spacecraft included a sensitive fluxgate magnetometer to measure DC and ULF magnetic fields in the low latitude ionosphere. The instrument included a DC vector measurement at 1 sample/sec with a range of ± 45,000 nT whose primary objective was to enable accurate measurements of both Vx Bfields and Ex B drifts. The magnetic field data also address a variety of important scientific research topics involving ionospheric and magnetospheric current systems. Here, we present C/NOFS magnetometer observations of low latitude ionospheric currents associated with the equatorial electrojet and dynamo currents. We show vector measurements that reveal closure currents and tidal forcing that vary with local time and longitude. With its unique low inclination (13 degree) orbit and long life (7.5 years) of continuous measurements, the C/NOFS magnetometer data present a fresh view of important electrodynamic processes in the earth's low latitude ionosphere.