Equatorial Ionospheric Electric Fields During the September 2005 CAWSES Campaign

Ionospheric electric fields have been measured with the Jicamarca incoherent scatter radar since the late 1960's. However, these observations very rarely covered periods longer than a few days. We present vertical plasma drift measurements obtained during September 12-22, 2005 to study the variability of the equatorial zonal electric fields. During this period, which covered mostly the recovery phase of two moderate geomagnetic storms, the equatorial electric fields showed large prompt penetration and disturbance dynamo effects and quiet time variability. We compare these observations with climatological quiet time and disturbance electric field patterns and discuss their relationship to the interplanetary electric field and high latitude disturbance parameters. We also examine the effects of the perturbation vertical drifts on the generation of equatorial and plasma depletions.