MEASUREMENTS OF THE DIRECTION OF THE SOLAR-WIND USING INTERPLANETARY SCINTILLATION

EISCAT observations of the interplanetary scintillation of a single so urce were made over an extended period of time, during which the orien tation of the baselines between the two observing sites changed signif icantly. Assuming that maximum correlation between the scintillations observed at the two sites occurs when the projected baseline is parall el to the direction of plasma flow, this technique can be used to make a unique determination of the direction of the solar wind. In the pas t it has usually been assumed that the plasma flow is radial, but meas urements of eleven sources using this technique have indicated conclus ively that in at least six cases observed at mid or high heliocentric latitude there is a significant non-radial component directed in four cases towards the heliocentric equator and in two cases towards the po le.