Geomagnetism

Equatorial Electric Field Model EEFM1

The Equatorial Electric Field (EEF) is created in the ionosphere by wind driven currents in combination with the Earth's magnetic field. The unique field geometry at the equator leads to charge buildup at dusk and dawn and consequently an eastward electric field along the magnetic equator. The EEF is responsible for driving many interesting phenomena in the ionosphere. Six years of satellite magnetic measurements from the CHAMP satellite have been used to extract the EEF at 108 km altitude. This model is a result of inverting the magnetic signature of the equatorial electrojet for the current density, solving Maxwell's equations to obtain the EEF, and then fitting the dataset to a climatological model. The model provides the climatological mean and variance of the EEF as a function of longitude, local-time, season, solar flux, and lunar local-time.

Fig. 1: The EEF as a function of longitude and local-time for different seasons.

Available EEFM1 Downloads
	Type	Format	Mbyte	Contents
	Model (driver and coefficients)	tar/gz	0.3	EEFM1 Model driver program source code and coefficients
	Article	PDF	0.3	Electric fields in the equatorial ionosphere derived from CHAMP satellite magnetic field measurements (preprint)

Patrick Alken