Observations of Electromagnetic Ion Cyclotron Waves Onboard the Cluster Satellites

The electric field and wave (EFW) instrument on board the four Cluster satellites samples normally 25 samples of the two spin-plane components of the electric field per second. This covers the whole frequency range of electromagnetic ion cyclotron (EMIC) waves, allowing unique possibilities to study these waves in the different parts of the magnetosphere, magnetosheath and solar wind, and within their boundary layers. Observations at the four Cluster satellites give information about the conditions of EMIC wave generation, the spatial extent of the wave source and its temporal development as well as wave propagation. We will present here examples of EMIC waves observed by the EFW instrument in the different regions and compare the EFW observations with simultaneous waves observed on ground.