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Monitoring surface currents in the Northern
Adriatic with high frequency coastal
radars Pierre-Marie Poulain1, Pierre Flament2,
Derek Young2, Cedric Chavanne2, Fabio Brunetti1
and Jeff Paduan3 1Istituto Nazionale di
Oceanografia e di Geofisica Sperimentale,
Trieste, Italy, E.U. 2University of Hawaii at
Manoa, Honolulu, Hawaii, USA 3Naval Postrgraduate
School, Monterey, California, USA
Istituto Nazionale di Oceanografia e Geofisica
Sperimentale - OGS
Paper Number OS51B-10
Main Sponsors Office of Naval Research Italian
Ministry of Education, University and Research
Naval Postgraduate School
The HF coastal radars
ABSTRACT As part of the ONR-sponsored DOLCEVITA
program high frequency coastal radars were
installed along the northern Italian coast
starting in September 2002 to monitor the surface
circulation in most areas of the Northern
Adriatic until the end of 2003. The high
frequency radars used are WERA and CODAR systems
operated at relatively low frequency (16 and 12.5
MHz, respectively). Maps of radial surface
currents are produced on a hourly basis at each
of the sites. Maximum ranges exceeding 120 km are
obtained mostly during the night. In order to
assure high quality of the data, calibration
exercises were conducted at all sites. After
eventual corrections, the data from all the
radars were combined to produce maps of vectorial
surface currents. Preliminary results obtained
with the radar data are presented, including
examples of maps of radial currents for each
site, maps of spatial coverage, and maps of
surface currents combining the data of two or
three radars. The latter show strong mesoscale
variability highly correlated with the
distribution of water properties such as the sea
surface temperature inferred from satellite
sensors.
Preliminary Results
The HF coastal radars used are WERA systems
manufactured by Helzel Messtechnik,
Kaltenkirchen, Germany in collaboration with the
University of Hamburg. They are operated near 16
MHz in both beam-forming and direction-finding
modes. Three radar sites were installed along the
Italian coast south of the Po River delta. The
northernmost site located on the delta (Faro di
Goro, Goro) includes a linear array of 16
antennas (beam-forming), whereas the intermediate
(Punta Marina, Ravenna) and the southernmost
(Monte San Bartolo, Pesaro) sites consist of 4
antennas installed in a square pattern
(direction-finding). A SeaSonde radar
manufactured by Codar Ocean Sensors in Los Altos,
California was installed in Ancona in April 2003
and was operated near 12.5 MHz for about two
months. Clock synchronization of the radar sites
is achieved via GPS whereas data telemetry and
remote logins are possible through GPRS mobile
phones.
Radial maps and spatial coverage
Radar Calibrations
Various calibration exercises were conducted in
order to validate the radar results and/or to
improve the algorithms used to process the data.
These include boat calibrations in front of each
site to measure the real patterns of the
receiving antennas and inter-sites calibrations
(e.g., pairs of radars in bi-static mode) to
assess the temporal stability of the systems.
Examples of radial maps for the Pesaro site
showing night (top) and day (bottom) maps and
corresponding Bragg spectra.
Maps of surface currents
Examples of Goro calibration results gain vs.
azimuth for signal coming at 10 incidence angle
(left) and difference between real and calculated
angle (typically less than 5 ).
Ancona calibration results Sample radial
coverage map including plots of the theoretical
(smooth circles) and measured (distorted arcs)
angular antenna pattern response functions for
the two, orthogonally mounted loop antennas that
are part of the SeaSonde direction finding system.
Rx
Tx
Acknowledgments We would like to thank the
following individuals for helping with the
installation logistics and with the data
processing Jérome Aucan, Riccardo Barbanti,
Alessandro Bubbi, Roberto Cecco, Cédric Chavanne,
Davide Deponte, Michele Deponte, Benedicte
Dousset, Io Flament, Mael Flament, Klaus-Werner
Gurgel, Thomas Helzel, Oliver Koshe, Paolo
Mansutti, Elena Mauri, Philip Moravcik and Giulio
Notarstefano. We would like to thank the
following individuals and institutions for
providing us with permits to install the WERA
stations and for helping with the local
logistics Monte San Bartolo, Pesaro Ente Parco
Naturale Monte San Bartolo, Provincia di Pesaro
Urbino, Comune di Pesaro, Comando 28Regg. Fant.
Pavia, ARPAM Pesaro, Dr. F. Piperno. Faro di
Goro, Goro Consorzio per la Gestione del Parco
Regionale del Delta del Po, Comune di Goro,
Provincia di Ferrara, Corpo Forestale dello
Stato, Fabrizio Farinelli e Valentino
Gianella. Punta Marina, Ravenna Capitaneria di
Porto di Ravenna, Agenzia delle Dogane, AGIP
Petroli, ARPA Ravenna. This research was
supported by the Office of Naval Research and the
Italian Ministry of Education, University and
Research.
CODAR electronics
Examples of radar-inferred surface currents
(arrows) and sea surface temperature (colors)
showing the spatial structure and temporal
evolution of the Po River Plume and cold coastal
layer.
Producing maps of surface current from the radial
maps of three radars (example on 7 Aug 2003)
Ancona CODAR radar with transmitting (Tx) and
(Rx) antennas.