ANALYSIS OF DATA-DRIVEN PARAMETRIC MODELS OF THE VERTICAL IONOSPHERICPROFILE FOR USE IN OBLIQUE PROPAGATION STUDIES

This paper compares parameterization techniques used for modeling the vertical profile of the ionosphere. In particular, comparisons of thre e-layer parameterizations driven by ionosonde data are performed. Quas i-parabolic, Chapman, and polynomial vertical profile models of the io nosphere are investigated. Optimization techniques applied at varying stages of the sensor output, ranging from direct inversion from the di gital ionogram image to fitting to true height output for the estimati on of parameters, are described. A Kalman-based filter is optionally u sed to track and filter the parameters. The performance of the various methods in producing the parameterized profile is analyzed through th e comparison of predicted versus measured values of the F-2 O-mode max imum observable frequency (MOF) on a 1250-km midlatitude oblique path. As a further benchmark, the monthly median model, FIRIC, is also used to generate oblique ionograms. It is found that three-layer parameter ized models perform well and can increase prediction accuracy over the median model, with the ability to reduce the rms error in MOF estimat ion from 2.38 MHz to 0.83 MHz.