Rocket measurement of the equatorial electrojet

Four Nike-Apache rockets, equipped with cesium vapor magnetometers, were launched in the equatorial electrojet region in March 1965. The rocket launched at the magnetic equator during the period of maximum electrojet current flow detected a 220-γ discontinuity in the magnetic field between 96 and 130 km. A peak current density of 13.5 amp/km² at 106 km was inferred from the data. A second rocket launched at the magnetic equator at night could detect no evidence, within a resolution of 5 γ, of any ionospheric currents. The remaining two rockets were fired at positions straddling the magnetic equator, where the local dip angle was approximately +5° and −5°. The observed magnetic field discontinuities indicate a north-south asymmetry in the equatorial electrojet, fitting a wide-current model to the north of the dip equator, and a narrow one to the south.