Abstract
High-frequency (HF) surface-wave (SW) radar systems have demonstrated their capability to capture the signals from seismic and non-seismic tsunami events using the estimation of surface current changes. Several ocean radar systems, operating in the upper HF band, were already optimized for tsunami alerting and installed for real-time tsunami monitoring at the coast. If the shelf extends tens of kilometers off the coast then the first appearance of tsunami waves can be monitored at the shelf quite early. On May 25, 2018, an HF SW phased-array radar system, operating in the lower HF band (6.9 MHz), detected strong changes in measured radial currents at distances up to 60 km off the coast. The system tracked the tsunami-like current pattern in the Bight of Benin. The wave propagation coincided with an atmospheric cold front passage. No earthquake occurred at that time but a strong atmospheric disturbance was present and it is the most likely reason for the detected disturbance. This localized event could be classified as a meteorological tsunami (meteotsunami). It is important to note that this is the very first detection of meteotsunami in the whole West African region. This detection showed the capability of the radar to measure unusual surface current velocities induced by tsunami waves using the lower part of the HF band. The detection of this tsunami-like event has shown good applicability of HF phased-array radar technology for offshore tsunami monitoring and providing safe navigation, in real-time. At the same time, it has been shown that a single HF SW radar system, originally optimized for vessel tracking at very long ranges using a proper output power, transmitter's noise optimization and integration time, can also be utilized as a component of Tsunami early warning systems (TEWS).
Highlights
High-frequency (HF) surface-wave (SW) radar systems give a unique capability to deliver simultaneous wide area measurements of ocean surface current fields and sea state parameters as well as maritime surveillance far beyond the horizon and under all-weather conditions
The paper is organized as follows: In Section 2 we briefly present some physical aspects behind meteotsunami generation and give some insight on how HF SW radar can detect it
The unique event in the Bight of Benin detected on 25 May 2018 by the radar system showed that this system is capable of measuring and tracking specific patterns of surface current velocity, having clear characteristics of a meteotsunami, far offshore
Summary
High-frequency (HF) surface-wave (SW) radar systems give a unique capability to deliver simultaneous wide area measurements of ocean surface current fields and sea state parameters as well as maritime surveillance far beyond the horizon and under all-weather conditions. Between 3 and 30 MHz to provide a large coverage of the ocean’s surface and is capable of extending to more than 300 kilometers offshore The outputs of these radar systems are used for various applications such as ocean currents and wave mapping, wave energy management, search and rescue and vessel traffic service. In this paper we continue considering the ability of HF SW radar, which operates at the lower frequency of the HF band, to provide tsunami measurements, albeit the optimal velocity resolution for surface tsunami currents is expected to be better than 5 cm/s [10].
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call