Estimation of Radio Refractivity From Radar Clutter Using Bayesian Monte Carlo Analysis

Abstract

Abstract-This paper describes a Markov chain Monte Carlo (MCMC) sampling approach for the estimation of not only the radio refractivity profiles from radar clutter but also the uncertainties in these estimates. This is done by treating the refractivity from clutter (RFC) problem in a Bayesian framework. It uses unbiased MCMC sampling techniques, such as Metropolis and Gibbs sampling algorithms, to gather more accurate information about the uncertainties. Application of these sampling techniques using an electromagnetic split-step fast Fourier transform parabolic equation propagation model within a Bayesian inversion framework can provide accurate posterior probability distributions of the estimated refractivity parameters. Then these distributions can be used to estimate the uncertainties in the parameters of interest. Two different MCMC samplers (Metropolis and Gibbs) are analyzed and the results compared not only with the exhaustive search results but also with the genetic algorithm results and helicopter refractivity profile measurements. Although it is slower than global optimizers, the probability densities obtained by this method are closer to the true distributions.

Estimation of the Atmospheric Duct From Radar Sea Clutter Using Artificial Bee Colony Optimization Algorithm

“…The actual surface-based duct parameters m = (0.13, −2.5, 40, 20) are chosen from the Ref. [1]. For the surface-based duct estimation, the control parameters of ABCO algorithm are given as follows: the number of colony size is 100, the number of food sources is 50, the maximum search limit is 100, and the maximum number of cycles is 500; the control parameters of PSO algorithm are given as follows: the population size is 50, the learning factor is 2.0, the inertia weight is 0.5, and the number of iteration is 50.…”

“…Atmospheric duct is a type of abnormal atmosphere structure above maritime boundary layer, caused by the abrupt changes in the vertical atmospheric temperature and humidity profiles above the sea surface [1]. Under the atmosphere duct environment, the nonstandard electromagnetic propagation can be observed, and the fundamental parameters and the performance of radar system and communication system can be drastically affected, such as the maximum operation range, creation of radar holes where the radar is practically blind, and strengthened sea surface clutter [2].…”

Retrieving Evaporation Duct Heights From Power of Ground-Based GPS Occultation Signal

“…Considering that the effects of evaporation ducts are manifested in radiowave propagation, it might be feasible to infer the structure of duct from the propagation measurements. Accordingly, a technique named as "refractivity from clutter" (RFC) is presented and developed which can be used to estimate the lower atmospheric refractivity using radar clutter [10][11][12][13][14][15].…”

Evaporation Duct Retrieval Using Changes in Radar Sea Clutter Power Versus Receiving Height

“…It is created by rapid anomalous changes in the vertical atmospheric temperature and humidity gradients immediately above water masses [1,2]. Many nonstandard propagation events can be induced by this ducting condition, including over-the-horizon detection, radar holes where the radar is effectively blind and positioning failure [3][4][5]. Accordingly, understanding the atmospheric environment is essential in evaluating and predicting the performance of maritime radar and communication systems.…”