Statistical study of lion roar emissions observed by the cluster spacecraft

Lion roars are intense narrow-band whistler-mode emissions with typical frequencies about 100 Hz. They are frequently occurring in the Earth´s magnetosheath. They are thought to be generated by local electron temperature instabilities. The four CLUSTER spacecraft allow us to study the Earth´s magnetospehere and its interaction with the solar wind in three dimensions. We have identified about 5000 time-frequency intervals containing the lion roar emissions during 2001 and 2005 in the data of the Spatio Temporal Analysis Field Fluctuations - Spectral Analyzer (STAFF-SA). We present results of a statistical study of Lion roar´s spatial, frequency and wave power distribution. We have found that Lion roars are more often observed on the dawn side than on the dusk side of the magnetosheath. We have investigated the orientation of Poyting vector directions of Lion roars calculated from measured spectral matrices using the Singular Value Decomposition (SVD).