Magnetic fields due to the magnetospheric ring current, together withtheir induced counterparts, must be correctly taken into account when modeling the geomagnetic field using modern observatory and satellite measurements. It is common practice to parameterize the induced field using a response function depending on a spherically symmetric electrical conductivity model of the solid Earth.
Here we show that Earth's metallic core should be included in such conductivity models, which has not previously been the case. Abrupt changes in the amplitude of the ring current during geomagnetic storms excite a wide range of frequencies, some of which can induce electrical currents in the core.