Ray Tracing Synthesis of HF Radar Signatures from Gaussian Plasma Clouds

The electron density distribution through ionized clouds produced by barium releases is often taken to be Gaussian for want of direct evidence to the contrary. Multiple frequency HF radar observations scattering cross-section and doppler shift versus time have been made during several releases for the primary purpose of measuring peak electron density as a function of time. Observations of this sort cannot be used to compute the electron density distribution directly because the cloud elongates along the earths magnetic field and thus the distribution is not one dimensional. These observations can however be used to test assumed distributions by ray tracing through a model cloud and comparing the predicted signatures with the observations. A detailed comparison of this nature has been made using a time-dependent gaussian cloud and the ITSA three-dimensional ray tracing program.