Incoherent scatter radar observations of polar cap F-layer ionization patches

This work presents observations and analysis of the horizontal and vertical structure of ionospheric plasma densities in and near approximately 40 polar cap F-layer ionization patches based on incoherent scatter radar data from Sondrestrom, Greenland. Optical data from an all-sky imaging photometer and in situ measurements of plasma density, plasma drifts, and precipitating particles from DMSP satellites are also used for comparison and to provide additional context for the radar measurements.; Measurements of plasma densities at the F-region peak showed that the large-scale features of the observed patches are consistent with an origin in a tongue of ionization and that polar holes of very low densities often occur in the morning sector after patch events. The statistical distributions of observed peak plasma densities were examined in relation to the practical problem of determining nominal background ionospheric densities and patch density enhancement ratios. Measurements of plasma density gradients forming patch edges are compared to density gradients interior and exterior to patches, and a possible relationship between observed large-scale latitudinal gradients in plasma density and plasma decay times is discussed. Measurements of horizontal patch sizes are also presented.; A unique algorithm developed specifically for this project is used to generate two-dimensional radar images of F-region plasma densities by taking into account the motion of the plasma over time. Patch shapes and sizes determined from these density-based observations are shown to agree closely with those determined from optical images of 6300-A airglow as well as with in situ plasma density measurements from DMSP satellites.; This work includes the first detailed study of vertical plasma density structure in and near patches. Vertical density profiles are shown to be relatively simple and depend principally on the peak density and peak altitude. Measurements of peak altitude, peak density, topside scale heights, and bottomside density gradients are presented, and the possible effects of proposed patch creation mechanisms on these parameters are discussed.; We also present suggestions for further incoherent scatter observations of polar cap patches using both existing facilities and the planned Polar Cap Observatory.