Toward Marine Environmental Predictions in the Mediterranean Sea Coastal Areas
345
in the coastal areas, capable of reducing the potential productivity of the local
nutrient rich waters, while in the Mediterranean open ocean areas the light availability shifts the Chlorophyll maximum at the subsurface.
In synthesis, the shelf/coastal areas of the Mediterranean Sea are coupled to the
open ocean flow field characteristics and forcing by many processes, such as:
1) The shelf net transport can be connected in several areas to basin scale features
(boundary currents);
2) The open ocean currents are modified by their interaction with the shelf areas
due to bottom stress compensation effects (Mellor and Wang, 1996) and/or
JEBAR processes (Joint Effects of Baroclinicity And Relief, Huthnance, 1984)
that can modify the proportion of barotropic/baroclinic energy in the flow field;
3) The she1f areas can produce rectification or damping of wave energy coming
from the open ocean through tidal internal or external waves, waves generated
by storms far off-shore, etc., enhancing also wave-tidal components energy
interactions;
4) The temperature extreme in the shelf areas can drive amplified air-sea flux
exchanges as shown by Roussenov et al. (1995) and Castellari et al. (1998).
Several upwelling areas are known to exist on the southern and eastern boundaries of the Mediterranean (Eastern Aegean Sea, Eastern Adriatic Sea and
southern Sicilian coasts) and this creates large air-sea temperature differences
that enhance the turbulent surf ace flux exchanges. The Northern African coasts
have a relative maximum of temperatures produced by downwelling favorable
winds and large positive heat net fluxes. Due to this, the Northern African shelf
areas show the basin largest heat gains during summer and largest heat losses
during winter;
5) Lateral heat and salt fluxes at the slope/open ocean interface can drive the shelf
areas. An example of this process is realized in the Adriatic Sea which looses
heat during winter on its N orthern shelf areas and regains it from the Otranto
Strait at the sub surf ace (Artegiani et al., 1997). This lateral flux compensation
mechanism can be delayed in time thus giving rise to a possible nonlinear feedback between the open ocean and the shelf areas. The lateral salt flux feedback
can also be active due to the river runoff effects that are in the long term compensated by saltier waters arriving on the shelf;
6) The shelf areas serve as a source of dissolved nutrients, particulate and dissolved organic matter and inorganic matter for the open ocean areas. This
source controls the amount of nutrients exported in the deep ocean areas by
simple transport mechanisms and/or regeneration of organic material by the
pelagic food web. On the other hand, in upwelling coastal areas, the shelf areas
work as a sink of nutrients for the deep ocean. This complex interaction
between shelf and open ocean areas is mediated by the pelagic and benthic food
web dynamics;
345
in the coastal areas, capable of reducing the potential productivity of the local
nutrient rich waters, while in the Mediterranean open ocean areas the light availability shifts the Chlorophyll maximum at the subsurface.
In synthesis, the shelf/coastal areas of the Mediterranean Sea are coupled to the
open ocean flow field characteristics and forcing by many processes, such as:
1) The shelf net transport can be connected in several areas to basin scale features
(boundary currents);
2) The open ocean currents are modified by their interaction with the shelf areas
due to bottom stress compensation effects (Mellor and Wang, 1996) and/or
JEBAR processes (Joint Effects of Baroclinicity And Relief, Huthnance, 1984)
that can modify the proportion of barotropic/baroclinic energy in the flow field;
3) The she1f areas can produce rectification or damping of wave energy coming
from the open ocean through tidal internal or external waves, waves generated
by storms far off-shore, etc., enhancing also wave-tidal components energy
interactions;
4) The temperature extreme in the shelf areas can drive amplified air-sea flux
exchanges as shown by Roussenov et al. (1995) and Castellari et al. (1998).
Several upwelling areas are known to exist on the southern and eastern boundaries of the Mediterranean (Eastern Aegean Sea, Eastern Adriatic Sea and
southern Sicilian coasts) and this creates large air-sea temperature differences
that enhance the turbulent surf ace flux exchanges. The Northern African coasts
have a relative maximum of temperatures produced by downwelling favorable
winds and large positive heat net fluxes. Due to this, the Northern African shelf
areas show the basin largest heat gains during summer and largest heat losses
during winter;
5) Lateral heat and salt fluxes at the slope/open ocean interface can drive the shelf
areas. An example of this process is realized in the Adriatic Sea which looses
heat during winter on its N orthern shelf areas and regains it from the Otranto
Strait at the sub surf ace (Artegiani et al., 1997). This lateral flux compensation
mechanism can be delayed in time thus giving rise to a possible nonlinear feedback between the open ocean and the shelf areas. The lateral salt flux feedback
can also be active due to the river runoff effects that are in the long term compensated by saltier waters arriving on the shelf;
6) The shelf areas serve as a source of dissolved nutrients, particulate and dissolved organic matter and inorganic matter for the open ocean areas. This
source controls the amount of nutrients exported in the deep ocean areas by
simple transport mechanisms and/or regeneration of organic material by the
pelagic food web. On the other hand, in upwelling coastal areas, the shelf areas
work as a sink of nutrients for the deep ocean. This complex interaction
between shelf and open ocean areas is mediated by the pelagic and benthic food
web dynamics;