On the origin and spatial extent of high-latitude F region irregularities

Evidence for the direct production of macroscale irregularities by structured, soft electron fluxes is employed to form the basis for a model for the transport and decay of such structures and the role of plasma instabilities in the production of smaller irregularities. Large scale structures were defined with wavelengths of at least 10 km, intermediate between 0.0-10 km, and short less than 10 m. Data were gathered by means of a rocket flight into the auroral oval and radar scans of 10-350 km altitudes for electron density contours. The radar data indicated that the large-scale structure in the F region plasma was in the main due to electron precipitation. The instability of the structures caused the emergence of smaller scale irregularities in a dynamic balance of instability growth and damping. Additional productive sources which allow the greater than 100 km structures to pass over the North Pole intact are discussed.