Auroral kilometric radiation (AKR)

spaceweb@oulu.fi - last update: 2 December 1998, 1000 UT (RR)

Auroral kilometric radiation (AKR) is bursty electromagnetic emission at about 100 - 500 kHz related to auroral arcs, i.e., dusk and evening side discrete auroras. Because of this, field-aligned potential drops must play some role in AKR production. The source region altitude is about 3000 - 20000 km; however, at a given time only a small altitude range is operational.

The radiation is believed to be generated at frequencies near the local electron cyclotron frequency f_ce, which often acts as low-frequecy cutoff for the waves. It is composed of both extraordinary and ordinary modes, with the extraordinary mode dominating.

For more information see, e.g., Bahnsen et al. (1989).

References

• Bahnsen, A., B. M. Pedersen, M. Jespersen, E. Ungstrup, L. Eliasson, J. S. Murphree, R. D. Elphinstone, L. Blomberg, G. Holmgren, and L. J. Zanetti, Viking observations at the source region of auroral kilometric radiation, J. Geophys. Res., 94, 6643-6654, 1989.

See also

• Space Physics Text Book of Oulu