Ionospheric electrostatic fields and the equatorial electrojet

The electrostatic characteristics associated with the equatorial electro jet are investigated with the aid of a number of theoretical and experimental considerations. With regard to the peak electro jet current, an eastward component of electric force of magnitude 4×10−4 volt/meter drives a current of density 10−5 amp/meter2. In the region of maximum current the ionosphere is electrically neutral, but the electric field is created by an electrostatic charge distribution with an excess of electrons in the region east of the point with peak current and an excess of positive charges in the region to the west. The maximum of the difference in the number density of the negative and positive charges is 5×10−2 charge/ meter3 for the volume density, and 9×104 charge/meter2 for the surface density on the lower boundary of the E layer. These number differences, which represent extremely small departures from electrical neutrality in the ionosphere, indicate the prime importance of a surface charge distribution in producing the ionospheric electrostatic field. The vertical component of the electrostatic force has a maximum value of 4×10−4 volt/meter but vanishes at the point containing the peak electro jet current.