Distribution of irregularities in the northern polar region determined from HILAT observations

Three years' observations of the HILAT satellite from stations Sondre (Sondre Stromfjord), Churchill, and Tromso have been used to study the distributions of scintillations over the northern polar region. Two regions showed enhancement. One was an enhancement of phase scintillations when the line of sight to the satellite lay along an L shell and the observing station was under the auroral oval. The second enhancement is revealed most clearly by amplitude scintillations and maximizes in an annular region several degrees poleward of the auroral oval. The L shell enhancement is most likely associated with large-scale "blobs" of ionization in the auroral zone, whereas the second enhancement appears to be due to kilometer scale irregularities generated in the polar cap.