Coupling between equatorial and auroral ionospheres during polar substorms

The intense substorm activity following the geomagnetic sudden commencement on 8 August 1972 at 2354 UT and on 9 August 1972 at 0037 UT had reversed the eastward electric field at the equatorial station Jicamarca between 0700 and 1200 UT, and this was preceded by similar changes in the westward electric field in the auroral region. This abnormal change at the equatorial latitudes in the American zone (in the night-time) was closely associated with the westward electric field in the Indian zone (in the day-time) causing the counter-electrojet and the sudden disappearance of theq type of equatorialEs. The reversal of the electric field at Jicamarca had caused the generation of theF region irregularities associated with range spreadF. It is suggested that on some occasions the counter equatorial electrojet currents are caused due to the reversal of the equatorial electric fields by the spreading of the auroral electrojet currents to the low latitudes following geomagnetic storms. This suggests a possible link between the equatorial ionosphere and the magnetosphere through the auroral latitudes.