Estimation of ocean surface currents beyond the region of overlap of dual-site HF radar

High-frequency ground wave radar (HFGWR) has emerged as a valid tool for the sensing of ocean parameters. If there are at least two radars covering the same patch of ocean then geometric considerations can be used to construct a complete vector current. Unfortunately, the region of overlap for two radar sites is smaller than the total single site coverage and other techniques are needed to estimate vector currents outside the common coverage area. The continuity of flow equation uses knowledge of vector currents within the overlap and radial current information outside the overlap to extrapolate tangential current data outside the overlap thereby increasing the region where vector current information is known. This approach has not been previously applied to a narrow-beam, long-range radar. Tests of the radar facilities conducted in the summer and fall of 2002 show that this technique achieved good comparisons between the radar-derived vector currents and continuity-derived vector currents for ranges up to 350 km for one azimuthally adjacent range cell.