**12. Conclusions**


magnetic fields and the ring current indices derived from near-equatorial magnetic variations may provide new insight in and improved modeling of the physical processes linking the polar and equatorial geomagnetic disturbance phenomena and help resolving their common origin in the solar wind properties.

• The PC indices provide a great potential for space weather services by enabling monitoring of the input of solar wind energy to the magnetosphere where the energy is used to power disturbance processes such as polar and auroral activity, upper atmosphere heating, substorms, and geomagnetic storms. The PC indices enabling the input energy monitoring are derived from magnetic variations recorded at two oppositely located polar cap observatories only. The PCC indices improve the accuracy over other PC index versions. Using multiple sources for PCN and PCS indices would greatly improve service reliability.
