Inversion of Oblique Ionograms Using the Newton-Raphson Optimizer

The inversion of oblique ionograms allows for extraction of ionospheric state information and retrieval of electron density profiles at midpoints along oblique sounding paths, However, traditional inversion methods often face the problems of large computation and slow convergence. This paper presents an enhanced Newton-Raphson-based optimizer (NRBO) algorithm with dynamically adjusted decision factors (DF). It compares the inversion results with those obtained from various optimization algorithms. Experimental results demonstrate that the new algorithm outperforms the improved Particle Swarm Optimization (PSO) algorithm in both inversion accuracy and computational speed. In a multi-layer Quasi-Parabolic Segment (QPS) ionospheric model inversion scenario, even with an observation error increase of 10 km, the inverted electron density profiles closely approximate the true values, showcasing robust noise resistance. Thus, this method proves suitable for practical oblique ionogram inversion based on actual measurements.