Future Contribution of HF Radar WERA to Tsunami Early Warning Systems

High-frequency (HF) surface wave radars provide a unique capability to detect targets far beyond the conventional microwave radar coverage but also could contribute to the development and improvement of Tsunami Early Warning Systems. The HF radar system WERA is an oceanographic radar placed at the coast and providing simultaneous wide area measurements of ocean surface current fields and sea state parameters. This paper describes the simulation of tsunami related signatures observed by HF radar at long ranges in case of a tsunami travelling towards the coast. A tsunami event is modeled using the oceanographic HAMburg Shelf Ocean Model (HAMSOM), which has high spatial and temporal resolution and gives the ocean surface currents induced by an approaching tsunami. The tsunami current velocity is converted into modulating signals and superimposed on measured antenna signals of the WERA radar. The possible ocean surface current changes due to a tsunami event are evaluated using fast update of the radar backscattered spectra. The proposed tsunami detection technique is based on the ordered-statistics constant false alarm rate (CFAR) detection algorithm applied to the entropy filed of surface currents. It gives an opportunity to issue an automated tsunami alert during the real-time monitoring by the WERA radar. Anna Dzvonkovskaya I Klaus-Werner Gurgel