Toward Marine Environmental Predictions in the Mediterranean Sea Coastal Areas
355
Multidisciplinary Mediterranean Moored Array (M3A) is a buoy system with three
moorings, each of them specialized for a selected task, at a distance of less than a
kilometer from each other, communicating with underwater acoustic telemetry.
The "mother" buoy is the air-sea interaction buoy and it is made of a large surf ace
buoy with air-sea interaction parameter sensors and subsurface fixed depth sensors
measuring temperature, conductivity, dissolved oxygen down to 500 meters. The
second buoy is constituted of a upward looking ADCP located at about 500 meters
which measures the current profile with a resolution of about 20 meters. The third
mooring has sensors placed at high resolution in the first 100 meters corresponding
to the upper thermocline region and the euphotic zone for the Mediterranean open
ocean waters. The fixed depth sensors measure temperature, conductivity, and dissolved oxygen in the second mooring and in addition to those turbidity, fluorescence, PAR and nitrates on the third mooring line. This new design alIows for easy
maintenance of the third mooring line every two months and the continuation of
the observations even in case of failure of parts of the system. The first and third
line are connected with subsurface acoustic telemetry, which allows the real time
transmis sion of data from the mother buoy to the land stations via celIular phone
technologies or satellite links.
The most important part of the real time observing system in the Mediterranean
is given by the satellite sea level anomalies (SLA) that are computed along the
tracks ofthe two different satellites having altimeters on board. As an example, the
track coverage given by Topex/Poseidon and ERS-2 for a two week period is
shown in Fig. 17.7. This data set gives information on the mesoscale eddy field but
for the Mediterranean the signal is small (order of several cm). In the past, the signal was analyzed in order to show that the orbit corrections could be done with the
required accuracy (Lamicol et al., 1995) and finalIy the sea level anomalies were
shown to be consistent with in situ observations. In addition to this important data
set, the remotely sensed sea surf ace temperature is also analyzed in near real time
with multichannel algorithms aud released for assimilatiou every week.
The satellite data sets together with the VOS system for the Mediterranean form
the basis of the large scale observing system. However, there are unsolved problems related to this system that it is interesting to discuss. First of alI the system
does not consider any salinity measurements yet that is a serious lack of information for the Mediterranean. Recent developments in satellite sensors, the ARGO
floats and gliders cou1d solve the problem but the sampling strategy should be evaluated. Second of alI, the satellite altimeter still gives only sea surface topography
anomalies and there is a problem in the definition of an optimal "synthetic geoid"
to retrieve the absolute dynamic topography which is the observable for the
dynamical model. Thirdly, the VOS system is quite expensive because it is manmanaged and environmentally polluting due to the loss of instruments on the ocean
floor. Concentrating technological development into these areas should solve these
problems in the near future.
Coupled to this large-scale system we conceive a coastal system that monitors
the same quantities of the basin scale system but at higher space-time resolution to
355
Multidisciplinary Mediterranean Moored Array (M3A) is a buoy system with three
moorings, each of them specialized for a selected task, at a distance of less than a
kilometer from each other, communicating with underwater acoustic telemetry.
The "mother" buoy is the air-sea interaction buoy and it is made of a large surf ace
buoy with air-sea interaction parameter sensors and subsurface fixed depth sensors
measuring temperature, conductivity, dissolved oxygen down to 500 meters. The
second buoy is constituted of a upward looking ADCP located at about 500 meters
which measures the current profile with a resolution of about 20 meters. The third
mooring has sensors placed at high resolution in the first 100 meters corresponding
to the upper thermocline region and the euphotic zone for the Mediterranean open
ocean waters. The fixed depth sensors measure temperature, conductivity, and dissolved oxygen in the second mooring and in addition to those turbidity, fluorescence, PAR and nitrates on the third mooring line. This new design alIows for easy
maintenance of the third mooring line every two months and the continuation of
the observations even in case of failure of parts of the system. The first and third
line are connected with subsurface acoustic telemetry, which allows the real time
transmis sion of data from the mother buoy to the land stations via celIular phone
technologies or satellite links.
The most important part of the real time observing system in the Mediterranean
is given by the satellite sea level anomalies (SLA) that are computed along the
tracks ofthe two different satellites having altimeters on board. As an example, the
track coverage given by Topex/Poseidon and ERS-2 for a two week period is
shown in Fig. 17.7. This data set gives information on the mesoscale eddy field but
for the Mediterranean the signal is small (order of several cm). In the past, the signal was analyzed in order to show that the orbit corrections could be done with the
required accuracy (Lamicol et al., 1995) and finalIy the sea level anomalies were
shown to be consistent with in situ observations. In addition to this important data
set, the remotely sensed sea surf ace temperature is also analyzed in near real time
with multichannel algorithms aud released for assimilatiou every week.
The satellite data sets together with the VOS system for the Mediterranean form
the basis of the large scale observing system. However, there are unsolved problems related to this system that it is interesting to discuss. First of alI the system
does not consider any salinity measurements yet that is a serious lack of information for the Mediterranean. Recent developments in satellite sensors, the ARGO
floats and gliders cou1d solve the problem but the sampling strategy should be evaluated. Second of alI, the satellite altimeter still gives only sea surface topography
anomalies and there is a problem in the definition of an optimal "synthetic geoid"
to retrieve the absolute dynamic topography which is the observable for the
dynamical model. Thirdly, the VOS system is quite expensive because it is manmanaged and environmentally polluting due to the loss of instruments on the ocean
floor. Concentrating technological development into these areas should solve these
problems in the near future.
Coupled to this large-scale system we conceive a coastal system that monitors
the same quantities of the basin scale system but at higher space-time resolution to