Response of large-scale geoelectric fields to identified interplanetary disturbances and the equatorial ring current Original Research Article

The changes in the geoelectric field G (mV/km) between Hawaii and Guam are examined during four small geomagnetic disturbances in 1995 and 1996 when interplanetary magnetic field and plasma data are available to provide the interplanetary integrated Poynting flux ε input to the magnetosphere. In agreement with a previous study of the geoelectric field at the time of the encounter of an interplanetary magnetic cloud event with the magnetosphere, we conclude that the maximum geoelectric field across this near-equatorial route can be estimated to better than about 50% if the interplanetary conditions are known by using the expression G = 2.3 × 10−11 ε(W).