Some Examples of the Effects of the Poleward F-layer Trough Wall on Ground Range and Azimuth Determination in an OTH Backscatter System.

摘要

This report describes the effects of a realistic trough wall model on azimuth and range errors expected for a OTH radar system. The strong north-south electron density gradients found in the trough wall result in considerable deviations from great circle propagation. Using a three-dimensional ray tracing program landing points of rays transmitted at 5 MHz were determined as a function of the initial azimuth and elevation angle. Using a spherical model ionosphere as reference, the effects of the realistic trough wall were expressed as range and azimuth errors. To determine the dependence of range and azimuth errors on the variability of the trough wall, upper and lower quartile values of the model were also used in the computations. Power calculations indicate that focusing effects > 15 dB can be expected for selected bundles of rays which just enter the trough wall. (Author)