Evaluation of Surface Current Mapping Performance by SeaSonde High Frequency Radar Through Simulations

The use of the HF radar to measure and map surface currents has proliferated along the coastlines of many countries for purposes of Search and Rescue, Oil Spill Management, Oceanographic and Fishery Science studies. In the US Navy, these surface current maps are being evaluated for operational use in real-time data assimilating coastal circulation models, and direct monitoring tools in environmentally sensitive operating areas. The SeaSonde HF radar, a DF system, was considered in this study. It uses the MUSIC algorithm to recover bearings from the Doppler backscatter spectrum of the sea surface. By varying the radial and antenna patterns, the simulated backscatter spectra were passed through the SeaSonde software suite for radial pattern recovery. This unprecedented approach directly evaluated SeaSonde’s MUSIC, and the associated uncertainties were examined against the simulated inputs of (1) fixed amplitude and phase deviations from the ideal antenna pattern, (2) measured antenna patterns and (3) decreasing SNR. It was found that using the measured antenna pattern to recover radials yielded least uncertainty, but a definitive prediction of MUSIC’s radial-recovery capability in relation to the pattern’s complex amplitude and phase structure remained illusive. The results highlighted the need to calibrate the military’s DF-systems for accurate azimuth recovery.