EISCAT studies of F region irregularities using beam scanning


  • J. K. Hargreaves,

  • C. J. Burns,

  • S. C. Kirkwood


A beam scanning program to study the F region irregularities of smaller scale has been run on the EISCAT UHF radar. At the 300-km level the scan covers 128 km in about 8½ min, there being north-south and east-west scans as well as periods with the beam stationary and directed along the local magnetic field direction. The paper gives examples of the variations of electron density observed at given ranges during a geomagnetically disturbed period. Power spectra suggest the presence of periodicities from one to several minutes during some sections of the runs. It is demonstrated that the velocities of field-aligned irregularities can be determined from their observed range-time behavior, and measurements thus made are compared with the plasma drift determined from tristatic reception. The irregularity motions appear to vary considerably during the time of one 8½-min scan and in some cases may indicate a propagating wave.