Comparison of Spectral Estimation Methods for Current Estimation by an HF Surface Wave Radar

This paper presents a comparative study of conventional spectrum estimation methods, such as the periodogram method, and modern techniques, such as the autoregressive and multiple signal classification methods, for current mapping by a high frequency surface wave radar. To calculate the radial current velocity, it is important to estimate its associated Doppler shift from the frequency spectrum. In addition to the conventional centroid method, a more robust Bragg frequency identification method, termed the symmetric-peak-sum, is proposed and examined in conjunction with each of the spectral estimation techniques. It has been found that a weighted sum of the radar-derived current estimates using these two methods generally provides a lower rms difference from the buoy measurements. The weighting ratio is optimized using a genetic algorithm. Field data indicate that a combination of these spectral estimation methods is capable of providing improvements in retrieved current velocities for various current conditions.