Relationship between ionospheric electric field and ground magnetic pulsations in the PC 3 domain at midlatitude

At middle latitudes, measurements of electric field fluctuations in the F region, in the Pc 3 frequency range is difficult. In France, with the incoherent scatter velocity measurements, three experiments have been performed. Technical performances and difficulties are described. Specific signal processing methods are presented, and pulsations in the ionosphere are described in time and in frequency form. They are identified by comparison with ground magnetic measurements through the use of autospectrum and coherency coefficient estimations. In the ionosphere we have found few events with amplitude waves higher than the detection level. When there was correlation between ionosphere and ground it was possible to infer the impedance of the ionosphere plus ground for the transfer between the electric field in the F region and the magnetic field on the ground. The deduced value of this impedance is approximately 10Ω. According to Hughes and Southwood's theory this means that the signals have a very short horizontal spatial scale