1 Solar System Physics, National Space Institute, Technical University of Denmark2 National Space Institute, Technical University of Denmark3 unknown4 Office for Study Programmes and Student Affairs, Administration, Technical University of Denmark
The magnetic measurements by the Orsted satellite in noon-midnight orbits have enabled the derivation of the global dawn-dusk oriented ionospheric currents from an Ampere's law closed loop line integral of the geomagnetic vector field along the satellite track. The globally integrated dawn-to-dusk ionospheric current is found to be proportional to the gee-effective solar wind electric field and is around 1 million ampere for a typical solar wind electric field of 2 mV/m. Dividing the Ampere integral into semi-orbit parts has enabled us to show that the hemispherical total current intensities depend on the respective polar cap conductivities, which relate to the daily and seasonally varying solar illumination. The more illuminated hemisphere conveys up to three times more current from dawn to dusk than does the less illuminated.
Geophysical Research Letters, 2000, Vol 27, Issue 20, p. 3273-3276