Average properties of wave emissions below 4 kHz in the inner magnetosphere based on the data of the STAFF-SA instruments on board the Cluster spacecraft.

We present a systematic study of whistler-mode emissions observed below 4 kHz in the inner magnetosphere. It is based on the data of the STAFF-SA instruments on board the Cluster spacecraft. The source of the data for our analysis and for our statistical study originated from measurements that the spacecraft made close to the perigee during the first four years of operation (2001-2004). We mainly focus our attention on the whistler-mode chorus emissions. We investigate the power-spectral density, polarization and propagation properties of the observed waves. We calculate the average values of the results obtained from the entire data set. We also calculate the statistical standard deviation of those results to confirm their systematic character. From our estimation of the Poynting flux based of the large data set we can confirm that the source of the chorus always is close to the equatorial plane. The parallel component of the Poynting flux is clearly oriented outwards from the equatorial plane. We also examine the angle deviation of the wave vector direction from the ambient magnetic field, ellipticity and the electromagnetic planarity. We investigate spatial distribution of chorus in the magnetic local time and radial distance.