Design parameters for an HF ocean surface radar installation

A long range HF radar system is being installed in the southern part of the Great Barrier Reef Lagoon as one component in a monitoring site for coral reef bleaching. The scientific requirements of the wider project are to monitor physical parameters which impact on coral bleaching and is guided by the "Degree Heating Days" product produced by the NOAA Coral Reef Watch group for bleaching event prediction. The relevant physical parameters are currents, waves and insolation. HF radar can provide monitoring solutions for the first two of these parameters. The design parameters for the installation follow from these requirements and we review the HF radar solutions available. The determination of range is common to all systems and is made by time domain measurements. The determination of azimuth from a radar station to the target pixel on the sea surface has traditionally been more difficult. The configuration of antennas is a critical issue for the installation and there are some trade-offs to be made. The phased array solution is technically superior but has a larger space requirement for the antennas on the coast. The crossed-loop plus dipole antenna system has a smaller antenna footprint but has limitations in the quality of the surface current coverage and is restricted to parameters which can be extracted from the first-order part of the Doppler spectrum.