Aerospace and Electronic Systems Magazine March 2018 - 56

HF Surface Wave Radar for Tsunami Alerting
centers globally. The tsunami simulation and decision support system is based on the Tsunami Observation and Simulation Terminal
(TOAST) system developed by gempa GmbH, which integrates a
precalculated tsunami scenario database and a graphics processing unit-based "on the fly" simulation. Although tide gauge data
are integrated as a traditional time series of water elevation, the
HF radar tsunami data are integrated in TOAST as a chain of virtual oceanographic sensors located at the shelf edge. If the tsunami
source is sufficiently far away and time is adequate to alert the
SeisComP3 and TOAST systems, then the HF radar data serve as
confirmation of timing and severity of the hazard, while calculating tsunami amplitude from the measured current velocity residuals and known bathymetry. When the tsunami source is nearby,
the HF radar tsunami alert takes a dominant role in the warning
system [27].

Figure 7.

The National Multi Hazard Early Warning System in Muscat, Oman,
launched on March 22, 2015.

used to confirm or cancel the decision on the basis of earthquake
features. For the far-field tsunami warning, this approach can be
extended to an inversion procedure, where the tsunami sources can
be reconstructed from sea-level observations by buoys, which provides an evaluation of the approaching tsunami hazard and estimation of the tsunami time of arrival. In a near-field tsunami warning,
this approach is not applicable, because the time needed to collect
and invert data from sea-level observations is too long. However,
HF radar-based observations of the tsunami wave make it possible
to continuously monitor an extensive coastal area for an incoming
tsunami hazard prior to reaching coastal sea-level gauges.
The first ideas of real-time tsunami information transfer from
ocean radars to warning centers were considered at least as early
as 2009 [16]. The information may contain either the residuals of
measured surface current velocity on a map for further data assimilation or a binary alert decision "yes/no." The format of necessary
information from an HF ocean radar system is usually specified by
the local TEWS. For example, the WERA ocean radar system is on
its way to being integrated into the newly opened TEWSs, each of
which requires different data support in real time, as described further. Unfortunately, the information how other ocean radar systems
are integrated in TEWSs is not available.

NATIONAL MULTI HAZARD EARLY WARNING SYSTEM IN
OMAN
The newly launched National Multi Hazard Warning Center in
Oman is one of the most sophisticated tsunami warning systems
in the world, applying a variety of well-proven state-of-the-art
subsystems. The combination allows the acquisition of data from
many different sensor systems, including seismic stations, a global
navigation satellite system, tide gauges, and two 9-MHz and two
13-MHz WERA ocean radar systems via a common interface (see
Figure 7).
The core of the tsunami warning system is the seismic realtime analysis system SeisComp3 used in most tsunami warning
56

NEAR-FIELD TSUNAMI ALERT NETWORK IN BRITISH
COLUMBIA, CANADA
Ocean Networks Canada (ONC), an initiative of the University of
Victoria, operates world-leading ocean observatories. ONC's new
initiative, Smart Oceans, aims to provide operational solutions for
marine and public safety, environmental protection, and sciencebased decision making. Since 2015, a WERA HF radar system has
become a component of the ONC initiative to develop a near-field
tsunami alert network consisting of different types of pressure
and seismic sensors, as well as ocean radars (see Figure 8) [28].
The radar system operating at 13.5 MHz has been installed near
Tofino, British Columbia, Canada, to cover up to 100 km off the
Canadian coastline. The newly developed tsunami alert software,
which allows fast mapping of ocean surface current in the area
and simultaneously generates tsunami alert mapping, is currently
being tested in a continuous automatic tsunami monitoring mode
24/7. It will soon be connected to the Web-Enabled Awareness Research Network (WARN) [29], which performs all detections and
confirmation calculations within 2 seconds for earthquakes and 2
minutes for tsunamis. A simple binary detection message will be
automatically transmitted from the radar system to the WARN. A
tsunami event will be publically declared only if a tsunami signature is simultaneously detected on three highly sensitive BPRs and
the ocean radar system.

CONCLUSION
In this article, an overview of HF surface wave radar development
for tsunami monitoring and alerting was presented. Special attention was paid to the ocean radar system concept, simulated scenarios, real measurements, and the perspective of integration into
early warning systems.
One of the key elements of any tsunami warning system is
an adequate real-time hydrodynamic detection network, which
is currently envisaged to consist solely of water level measuring
stations. However, the presented results using the operational HF
ocean radar systems showed that offshore current measurements
would be beneficial to draw the attention of tsunami warning deci-

IEEE A&E SYSTEMS MAGAZINE

MARCH 2018

Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine March 2018