Simultaneous observations of whistler mode waves by the DEMETER spacecraft and the Kannuslehto station

We use conjugate observations of magnetospheric whistler mode electromagnetic waves at frequencies up to 16 kHz to determine their typical spatial scales and propagation to the ground. For this purpose, we use data obtained by the DEMETER spacecraft at an altitude of about 700 km and by the ground-based Kannuslehto station in Finland. The overlap between the two data sets corresponds to more than 500 DEMETER half-orbits between November 2006 and March 2008. Two different approaches are used. First, specific wave events observed simultaneously by both the spacecraft and the ground station are analyzed in detail. Second, the correlations of the power spectral densities of measured signals are calculated as a function of the frequency and geomagnetic longitude/L-shell separation. These are used to determine typical longitudinal/L-shell correlation lengths and to discuss wave propagation to the ground.