Abstract
High Frequency Radar (HFR) technology refers to land based remote sensing instruments capable of measuring surface currents and ocean waves at ranges up to 200 km or more. HFR technology is widely acknowledged as a cost-efficient tool to monitor coastal regions and has potential use to monitor coastal regions all over the world. Globally, the number of HFR stations is steadily increasing. Regional networks provide real-time data in support of operational activities such as search and rescue operations, fast response in case of maritime accidents and spill of pollutants, and resource management. Each operator needs a general understanding of the working principles in order to ensure that instruments are managed properly. A set of harmonized quality assurance and quality control procedures is recommended, along with an effective approach to HFR data discovery and dissemination, to provide high quality measurements to the end users. Different documents providing best practices for operation and maintenance have emerged in the past years. They are oriented either to Direction Finding (DF) or Beam Forming (BF) systems, or to specific manufacturer’s radar systems. The main objective of this paper is to offer a comprehensive “Best Practices” document in an effort of ensuring consistency between different deployments and harmonized operations of HFR systems. This, regardless of system manufacturer, antenna design and setup. A homogeneous approach is given when possible, general concepts and definitions are introduced in order to provide a framework for both data processing and management steps. Examples are also given from the European HFR users with focus on Near Real Time data flow suitable for operational services.
Highlights
High Frequency ocean Radar (HFR) systems are cost-efficient tools to monitor coastal regions at a range of up to 200 km or more, with potential to monitor coastal regions all over the world
High Frequency Radar (HFR) technology relies on the Bragg resonant mechanism, that is a resonant backscatter resulting from coherent reflection of a transmitted radio wave by a particular train of ocean waves with half the wavelength of the transmitted signal
Antenna Tuning Within the theoretical limits given by the chosen operating frequency, the HF radar performances can be significantly reduced in case of a bad tuning of the transmit antenna, i.e., when significant fraction of the power is reflected back to the amplifier due to a mismatch of the impedance between the antenna and the amplifier at the given frequency
Summary
High Frequency ocean Radar (HFR) systems are cost-efficient tools to monitor coastal regions at a range of up to 200 km or more, with potential to monitor coastal regions all over the world. HFR technology relies on the Bragg resonant mechanism, that is a resonant backscatter resulting from coherent reflection of a transmitted radio wave by a particular train of ocean waves with half the wavelength of the transmitted signal. Since ocean waves travel with a non-zero speed, the frequency of the backscattered radio wave is Doppler shifted. For a radar transmitting at a central frequency f0, two narrow peaks (Bragg peaks) are theoretically expected in the backscattered spectrum, shifted ± f from f0, and associated with the waves traveling toward (right peak) and away (left peak) from the radar, along the radial direction (Crombie, 1955). When ocean waves propagate over a current field, an additional Doppler shift adds up to the one previously described
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