An Index (PC) Aimed at Monitoring the (P)olar (C)ap for Magnetic Activity

PC is an index for magnetic activity in the (P)olar (C)ap. It is based on data from a single nearpole station, and aimed to monitor the polar cap magnetic activity generated by such solar wind parameters as the southward component of the interplanetary magnetic field (IMF), the azimuthal component of the IMF (By), and the solar wind velocity v. The station Thule, located in the village Qaanaaq in Greenland at 86.5 degrees geomagnetic invariant latitude, fulfills the requirement of being close to the magnetic pole in the northern hemisphere. The station Vostok at 83.3 degrees does the same in the southern hemisphere. The PC index is derived independently for these two stations. The PC-index is based on an idea by Troshichev et al. (1979) and developed in papers by Troshichev and Andrezem (1985), ennerstrom et al. (1991). Earlier data for 1975-1982 appear in Troshichev et al. (1991). The data from 1975 to the present are published in Report UAG-103, available from the NOAA National Centers for Environmental Information (formerly National Geophysical Data Center).