ULF OBSERVATIONS ON CLUSTER

G. Gustafsson(1), K. Mursula(2), T. Carozzi(1), B. Lybekk(3), K. Stasiewicz(1),

P Tanskanen(2), H. Singer(4), H. Laakso(5)

(1) Swedish Institute of Space Physics, Uppsala Division, Uppsala, Sweden

(2) University of Oulu, Oulu, Finland

(3) University of Oslo, Oslo, Sweden

(4) NOAA Space Environment Center, Boulder, Co., USA

(5) SSD/ESTEC, Noordwijk, The Netherlands

Georg.Gustafsson@irfu.se Fax +46 18 4715905

Waves in the one to a few hundred mHz frequency range carry a large fraction of the

energy in the magnetosphere and are, therefore, of importance for the energetics and

particle transport in that region. The four-point measurements with Cluster give a

unique possibility to study the generation, source, mode structure, spatial

occurrence, temporal development and propagation of these waves. Multispacecraft

observations give unambiguous evidence for the position dependence of several

wave parameters. Phenomena related to the solar wind interaction with the

magnetopause or the bow shock have been suggested as a source for some wave

modes. These regions are covered by Cluster observations. Other modes are

expected to be related to bouncing ions of a few keV which are also observed.

Observations mainly with the electric field instrument of various types of waves in

the different regions with preliminary conclusions will be reported.