CHAPTER 3
Surface Dynamics of a Coastal Area off Ancona (Adriatic Sea)
G. BudillonI, E. PaschinP, A. Simioli!, and E. Zambianchi 1
ABSTRACT
In the framework of the PRISMA 2 programme, an HF Coastal Dynamics Applications Radar
(CoDAR) has been utilized starting in July 1997, in order to identify surface frontal structures
characterizing the Italian coast of the Adriatic Sea and to study the surface circulation, which
plays a fundamental role in heat and momentum transfer processes between coastal and offshore areas.
Near-surface currents in the coastal area between Ancona and Senigallia derived from the
shore-based HF radar have been mapped at weekly intervals at a resolution of 1.5 km over an
area of approximately 30 x 30 km.
Preliminary results show a southeastward (Le. alongshore) coastal jet that extends its influence as far as 10 km from the coast; farther offshore a cyclonic eddy, with a diameter of 10-20
km typically occurs. This circulation can occasionally be reversed showing an anticyclonic eddy
that forces a northward coastal current with a far less energetic signature.
Introduction
Recently the Italian coastal areas of the Adriatic
Sea have been intensively investigated in the
framework of the Italian national PRISMA-2
research programme. a multidisciplinary study
focussed on the physical and biochemical
processes that determine the fate and the distribution of pollutants discharged in the Adriatic Sea.
The general circulation of the Adriatic Sea, as
derived by several experimental and modelling
studies, shows a seasonal and annual cyclonic
characteristic. Typically the surface circulation
in the southern and middle Adriatic Sea consists
of a smooth flow encircling cyclonically the
entire basin, while during the winter the general
circulation consists of several cyclonic gyres
(Artegiani et al. 1997; Malanotte Rizzoli and
Bergamasco 1983; Franco et al. 1982; Paschini et
al. 1993).
The cyclonic circulation of the Adriatic Sea is
intensified in the central coastal region around
43.5 N, where the local bathymetry shows a
strong slope over a wide longshore area
(Artegiani et al. 1980)
The flow along the Italian coastline is also
characterized by the presence of fresh waters of
river runoff origin. In particular, coastal waters
off Ancona show a strong seasonal variability of
the physical and bio-chemical parameters
depending on river discharges. The boundary
between this coastal freshwater strip and the
open sea is often characterized by the development and growth of mesoscale instabilities (see,
e.g. Bracalari et al. 1989, and references therein).
In the framework of the PRISMA 2 activities,
a special emphasis has been devoted to the study
of the coastal area off Ancona. both for its geographical setting and for the proximity of one of
the major cities on the Adriatic coast. In addition
to the traditional measurements extensively carried out over the whole basin. the objective of
characterizing the surface circulation in the
region immediately offshore (and upstream, with
respect to the prevailing coastal current) from
the city was pursued by means of a coastal radar
which was set up and has been working since
summer 1997. The data presented and discussed
here, in particular, refer to the months of August,
September and October 1997.
1 Istituto di Meteorologia e Oceanografia, Istituto Universitario Navale, Via Acton 38,80133 Napoli, Italy
2 Istituto Ricerca Pesca Marina, CNR, Ancona, Italy
P.M. Faranda. L. GugIielmo, G. Spezie (eels)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag ltalia 2001
Surface Dynamics of a Coastal Area off Ancona (Adriatic Sea)
G. BudillonI, E. PaschinP, A. Simioli!, and E. Zambianchi 1
ABSTRACT
In the framework of the PRISMA 2 programme, an HF Coastal Dynamics Applications Radar
(CoDAR) has been utilized starting in July 1997, in order to identify surface frontal structures
characterizing the Italian coast of the Adriatic Sea and to study the surface circulation, which
plays a fundamental role in heat and momentum transfer processes between coastal and offshore areas.
Near-surface currents in the coastal area between Ancona and Senigallia derived from the
shore-based HF radar have been mapped at weekly intervals at a resolution of 1.5 km over an
area of approximately 30 x 30 km.
Preliminary results show a southeastward (Le. alongshore) coastal jet that extends its influence as far as 10 km from the coast; farther offshore a cyclonic eddy, with a diameter of 10-20
km typically occurs. This circulation can occasionally be reversed showing an anticyclonic eddy
that forces a northward coastal current with a far less energetic signature.
Introduction
Recently the Italian coastal areas of the Adriatic
Sea have been intensively investigated in the
framework of the Italian national PRISMA-2
research programme. a multidisciplinary study
focussed on the physical and biochemical
processes that determine the fate and the distribution of pollutants discharged in the Adriatic Sea.
The general circulation of the Adriatic Sea, as
derived by several experimental and modelling
studies, shows a seasonal and annual cyclonic
characteristic. Typically the surface circulation
in the southern and middle Adriatic Sea consists
of a smooth flow encircling cyclonically the
entire basin, while during the winter the general
circulation consists of several cyclonic gyres
(Artegiani et al. 1997; Malanotte Rizzoli and
Bergamasco 1983; Franco et al. 1982; Paschini et
al. 1993).
The cyclonic circulation of the Adriatic Sea is
intensified in the central coastal region around
43.5 N, where the local bathymetry shows a
strong slope over a wide longshore area
(Artegiani et al. 1980)
The flow along the Italian coastline is also
characterized by the presence of fresh waters of
river runoff origin. In particular, coastal waters
off Ancona show a strong seasonal variability of
the physical and bio-chemical parameters
depending on river discharges. The boundary
between this coastal freshwater strip and the
open sea is often characterized by the development and growth of mesoscale instabilities (see,
e.g. Bracalari et al. 1989, and references therein).
In the framework of the PRISMA 2 activities,
a special emphasis has been devoted to the study
of the coastal area off Ancona. both for its geographical setting and for the proximity of one of
the major cities on the Adriatic coast. In addition
to the traditional measurements extensively carried out over the whole basin. the objective of
characterizing the surface circulation in the
region immediately offshore (and upstream, with
respect to the prevailing coastal current) from
the city was pursued by means of a coastal radar
which was set up and has been working since
summer 1997. The data presented and discussed
here, in particular, refer to the months of August,
September and October 1997.
1 Istituto di Meteorologia e Oceanografia, Istituto Universitario Navale, Via Acton 38,80133 Napoli, Italy
2 Istituto Ricerca Pesca Marina, CNR, Ancona, Italy
P.M. Faranda. L. GugIielmo, G. Spezie (eels)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag ltalia 2001