HF Radar Systems for Wave and Current Measurement
Klaus-Werner Gurgel ,
Georg Antonischki and
University of Hamburg, Institute of Oceanography,
Tropolwitzstrasse 7, D-22529 Hamburg, Germany.
Tel: +49-40-42838-5742, Fax: +49-40-42838-5713,
HF radar in oceanography make use of backscatter of electromagnetic waves
of 10 m to 50 m wavelength from the rough sea surface. The backscattered signal
can be analysed to derive ocean surface current and wave parameters. Several
HF radars have been developed all over the world and significant progress
both in technology and algorithms has been acheaved since the discovery of
the basic physics in 1955 by D. D. Crombie.
The main requirements for successful measurement of ocean waves are:
- Access to the second order reflections from the sea surface and
- an increased signal-to-noise ratio of the measured Dopper spectrum,
because the second order returns are much weaker compared to the
strong first order reflections, which are used to derive surface current
Based on these requirements, a new system called WERA
(WEllen RAdar) has been
designed within the European project SCAWVEX (Surface
Current And Wave Variability Experiments),
which brings together the potential of 8 partners
from 4 European countries. The second order returns are resolved by using
a linear antenna array and forming beams to different azimuthal directions.
Side lobes have to be suppressed carefully to avoid strong first order returns
from other directions to be misinterpreted as second order returns. A high
signal-to-noise ratio has been acheaved by parallel processing of the
receiving antenna signals and using an advanced FMCW technique for range
resolution, which can be set to 1.2 km, 600 m and 300 m.
WERA has been operated in the 27 MHz and 30 MHz band, giving working ranges
of up to 55 km for mapping current fields. With slight modifications,
operation on other frequency bands is possible.
Ocean surface current fields are derived from the radar data using the
University of Hamburg algorithms, the spatial distribution of wave hight
directional spectra are calculated using the University of Sheffield wave
algorithm. Both informations can be gained from the same data set, so
simultanous measurements of currents and waves are possible. This opens new
possibilities to environmental monitoring, coastal engineering and increasing
This work has been funded by the European Commision DG XII within the MAST-2
programme, project SCAWVEX, ct94-0103.
last update 21-Jan-1998