PortMap: a VHF ocean surface radar for high spatial resolution

A VHF ocean surface radar system operating at 152.2 MHz with a bandwidth of 1.5 MHz is producing surface currents on a spatial grid of 100 m. This is an appropriate spatial resolution for current map products in Ports and Harbours and around natural or built headland features. The design parameters for the new PortMap radar are discussed and sample data are shown using an early prototype for a narrow tidal inlet with a shipping channel and mudflats on each side. We show that eddy structures develop in the ebb flow which have special consequences for sediment transport in the alongshore direction across the mouth of the inlet. A second case study is shown where an alongshore current interacts with a headland to produce a recirculation of water on the leeward side. In both cases the 100 m spatial scale of the data points gives a well-sampled image for surface current.