Pi C pulsations

spaceweb@oulu.fi - last update: 7 January 1999, 1540 UT (RR)


ULF range continuous Pi C geomagnetic pulsations are generally seen in the morning sector and at the low-frequency end of the Pi 1 (1-40 s) range (Heacock, 1967). The magnetic activity consists of pulses spaced irregularly about 10 s apart and lasts up to several hours.

A very good correlation has been observed between the PiC and the auroral luminosity variation (Oguti et al., 1979, 1984; Arnoldy et al., 1982; Engebretson et al., 1983, 1986; Oguti and Hayashi, 1984; Burns and Cole, 1985; Burns and Craven, 1988; Grant and Burns, 1995). Thus it seems obvious that the pulsations are created by the pulsating auroras as the conductivity changes driven by the precipitation pulsations modulate both the ionospheric currents and field-aligned currents (see the model calculations by, e.g., Oguti and Hayashi (1984) and Grant and Burns (1995).

It has been suggested that the 3-s enhancement seen in the Pi1B should be called a special type of PiC related to resonant cavities, e.g., IAR (Grant and Burns, 1995; Arnoldy et al., 1998).


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