Mesoscale in the Western Mediterranean: interaction
with the large scale circulation and impact on vertical
transport of biogeochemical tracers
Joaquin Tintore, Jean Michel PinoL, Alberto Alvare~
Dept. de Fisica
Universitat de les Illes Balears
E-07071 Palma, Spain
1. The mesoscale in the Western Mediterranean circulation
Mesoscale is a dominant scale of motion in the world's oceans. During thc last decade,
the wide use of infrared imagery and altimetry, has shown that mesoscale structures are
ubiquitous and dominate the energy spectrum. These structures present a wide range of
space and time scales, from 10 to 100 km and 10 to 100 days, respectively. These features
present a large variety of patterns such as meanders, eddies, filaments or plumes and are
responsible for the existence of enhanced density and velocity shears. The observation of
mesoscale structures has therefore become a priority in recent years and significant efforts
are now devoted to resolve or parametrize mesoscale fluctuations ill occan circulation
models, both in large scale open ocean or more coastal studies. The structures observed
and their dynamics are however different in these two environments. In the study of
large scale open ocean circulation, adequate treatment or parametrization of turbulent
mesoscale eddies is needed since they enhance mixing and horizontal transport of heat,
salt, particulate matter, etc., which play an important role in the global ocean circulation.
In the coastal ocean, mesoscale feat.ures are important since they represent a major forcing
for cross-shore transport of properties. Another important differellce between open ocean
and coastal studies is that, while large scale eddies are generally isotropic, coastal features
are highly anisotropic, appearing usually as elongated filaments.
1.1 Observation of mesoscale features in the Western Mediterranean
As in most regions of the world's oceans, in depth analyses of satellite imagery carried
out in the last ten years in the Western Mediterranean evidenced systematic mesoscale
variability (La Violette, 1994). In situ experiments, focusing specifically on the importance
of mesoscale variability were carried out in different. sub-basins. Examples can be found in
the Balearic and Alborn sub-basins where int.ense and sharp density fronts and currents
exist. These experiments aimed at. providing a physical and dynamical description of
the vertical structure of frontal mesoscale features and at. investigating their interaction
NATO ASI Series. Vol. I 48
The Mathematics of Models for Climatology
and Environment
Edited by Jesus IIdefonso Diaz
© Springer-Verlag Berlin Heidelberg 1997
with the large scale circulation and impact on vertical
transport of biogeochemical tracers
Joaquin Tintore, Jean Michel PinoL, Alberto Alvare~
Dept. de Fisica
Universitat de les Illes Balears
E-07071 Palma, Spain
1. The mesoscale in the Western Mediterranean circulation
Mesoscale is a dominant scale of motion in the world's oceans. During thc last decade,
the wide use of infrared imagery and altimetry, has shown that mesoscale structures are
ubiquitous and dominate the energy spectrum. These structures present a wide range of
space and time scales, from 10 to 100 km and 10 to 100 days, respectively. These features
present a large variety of patterns such as meanders, eddies, filaments or plumes and are
responsible for the existence of enhanced density and velocity shears. The observation of
mesoscale structures has therefore become a priority in recent years and significant efforts
are now devoted to resolve or parametrize mesoscale fluctuations ill occan circulation
models, both in large scale open ocean or more coastal studies. The structures observed
and their dynamics are however different in these two environments. In the study of
large scale open ocean circulation, adequate treatment or parametrization of turbulent
mesoscale eddies is needed since they enhance mixing and horizontal transport of heat,
salt, particulate matter, etc., which play an important role in the global ocean circulation.
In the coastal ocean, mesoscale feat.ures are important since they represent a major forcing
for cross-shore transport of properties. Another important differellce between open ocean
and coastal studies is that, while large scale eddies are generally isotropic, coastal features
are highly anisotropic, appearing usually as elongated filaments.
1.1 Observation of mesoscale features in the Western Mediterranean
As in most regions of the world's oceans, in depth analyses of satellite imagery carried
out in the last ten years in the Western Mediterranean evidenced systematic mesoscale
variability (La Violette, 1994). In situ experiments, focusing specifically on the importance
of mesoscale variability were carried out in different. sub-basins. Examples can be found in
the Balearic and Alborn sub-basins where int.ense and sharp density fronts and currents
exist. These experiments aimed at. providing a physical and dynamical description of
the vertical structure of frontal mesoscale features and at. investigating their interaction
NATO ASI Series. Vol. I 48
The Mathematics of Models for Climatology
and Environment
Edited by Jesus IIdefonso Diaz
© Springer-Verlag Berlin Heidelberg 1997