EMIC Waves in the Magnetosphere

Plasma instabilities associated with ion and electron populations in the magnetosphere give rise to many types of hydromagnetic and ion cyclotron waves. The ultra-low frequency (ULF) magnetic field fluctuations associated with these waves are observed as geomagnetic pulsations. Observational data from spacecraft [CRRES, DE1 & 2, ISEE1 & 2, DMSP, IMP8) and numerous ground stations in Australia, New Zealand and Antarctica are used to study ULF waves in the magnetosphere and the ionosphere.

Studies of Pc1-5 waves have been undertaken near the high latitude Davis Antarctic station using a small network of magnetometers located in a square arrangement of side 120-150km. Direction of arrival determinations on daytime quasi-structured and unstructured Pc1-2 emissions show they are associated with sources on closed field lines in the outer magnetosphere. This boundary region just inside the magnetopause may also be the origin of a prenoon Pc1-2 band, possibly a consequence of electromagnetic ion cyclotron wave (EMIC) generation resulting from ion injection into the magnetosphere from the dayside cleft. It has also been shown that these waves may propagate over short distances (< 500 km) but are not propagated in the ionospheric F2 region waveguide.

For more information, contact Prof. B.J. Fraser