Improved spectral estimation of equatorial spread F through aperiodic pulsing and Bayesian inversion

Abstract

Observations of coherent scatter from plasma density irregularities associated with equatorial spread F made at Jicamarca with aperiodic radar pulses are presented. Aperiodic pulses are used to resolve range and frequency aliasing of the moderately overspread target. Two strategies are considered in which the radar interpulse period undergoes small and large variations, respectively. Both strategies perform satisfactorily, although the latter provides autocorrelation functions sampled more uniformly in time, which is advantageous, particularly when few samples are available. The nonuniformly sampled radar data that result are analyzed using a Bayesian approach based on maximum entropy. A scenario for combining aperiodic pulsing and spaced‐receiver radar imaging for observing spread F is described. With this technique, it may be possible to estimate the irregularity power and energy spectral density versus wave number.