A Comparison of Surface Current Fields derived by
Beam Forming and Direction Finding Techniques
as applied by the HF Radar WERA
Presented at the IGARSS'97, HF Radar Special Session, Paper 3
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,
A full paper has been published in the conference
HF radar in oceanography make use of backscattering of electromagnetic waves
of 10 m to 50 m wavelength from the rough sea surface. The backscattered signal
can be analysed to derive surface current and ocean wave parameters. Several
HF radars have been developed all over the world and significant progress has
been acheaved since the discovery of the basic physics in 1955 by D. D. Crombie.
In Germany, the work on ground wave HF radar started in 1980 adopting
NOAA's CODAR (COastal raDAR), introduced in 1977 by D. E. Barrick.
Many modifications have been applied to the CODAR since then and the system
has been deployed during numerous experiments. In 1987, a shipborne version
allowed for measuring the circulation at the Arctic Front and near the ice
edge in the North Atlantic. Recent developments within the European project
SCAWVEX (Surface Current And Wave Variability Experiment) lead to a new design
called WERA (WEllen RAdar).
WERA has been designed to offer as much flexibility as possible, both in
hardware and the algorithms to process the backscattered sea echos. This
flexibility allows for simultanous measurements with a 4 element squared CODAR
array and a 12 element linear array. In Spring 1996, two WERA systems have been
deployed north and south the Rhine mouth at the Dutch coast. In addition to
WERA, two CODAR systems have been operated at the same sites, alternating the
time slices with WERA. This setup of the HF radars allows for comparisons
between CODAR and WERA as well as between the different algorithms for
azimuthal resolution, like direction finding and beam forming. This paper
decribes the systems and algorithms used, some differences identified in the
surface current fields measured, and finally tries to show up the advantages
and difficulties of the different algorithms.
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