Electric field sources in the quiet plasmasphere from whistler observations

Existing evidence for the ionospheric dynamo being the source of quiet time electric fields in the plasmasphere is reviewed. Part of a 24 h set of whistler data recorded continuously at Sanae, Antarctica (L = 4), during quiet magnetic conditions (average Kp = 1) is analysed to obtain westward electric fields in the equatorial plane. It is found that for periods of outward flow of plasma during the noon-midnight local time period, the electric fields are consistent with the dominant source being the ionospheric dynamo. There is some evidence that during the evening period of inward flow the electric fields are magnetospheric in origin. The observed whistler duct convection patterns do not fit either of two theoretical models, which invoke a magnetospheric field but not a dynamo field. (author)