Ground observations of kinetic Alfvén waves

Ground observations of locally confined, very intense, drifting current systems by the EISCAT magnetometer cross in correlation with GEOS 2 measurements will be explained in terms of kinetic Alfvén waves. In the ground based magnetograms the events are characterized by strong pulsations with amplitudes in the horizontal component up to 1000 nT and periods of about 300s and longer. They occur in the evening hours adjacent to the poleward side of the Harang discontinuity with the onset of a substorm. At the same time the inner edge of the plasma sheet passes the GEOS 2 position, magnetically conjugate to ground stations. The common features of four events during Nov and Dec 1982 will be discussed.