Rapid Assessment ofthe Coastal Ocean Environment
215
tion, with its mesoscale variability, there are the wind-driven currents on the from
local and remote storms (including the Sicilian coastal current) and upwelling off
Sicily. Tides, inertial, gravity, surface, and continental shelf waves occur. This
region contains active water mass modification processes between the fresher and
warmer Atlantic origin water mass and the saltier and colder Levantine water mass.
The free jet filaments of the AIS in the Ionian Sea exhibit considerable variability
in occurrence and location as they thread their way to the Cretan passage. In addition a number of (semi-) permanent and transient sub-basin scale to mesoscale
cyclonic and anticyclonic vortices occur which are interactive with the jets and
each other. The variability of the circulation structures and sub-basin scale features
has been studied by Malanotte-Rizzoli et al (1999). Figs. 11.4 and 11.5 will be discussed in more detail below.
The Gulf of Cadiz - Fig. 11.1, introduced earlier, and Fig. 11.6 present aspects of
the circulation and topography of the Gulf of Cadiz. For our purpose we de fine the
Gulf ofCadiz as the area east of9°W and north of35°N. To the north and east it is
bounded by the Portuguese, Spanish and African coast. The western and southern
boundaries are open; another narrow open boundary exists in the east at the Strait
of Gibraltar. The west-east extension is about 270 km, in north-south direction it
extends over about 250 km. Maximum water depth is about 3000m in the southwest corner. Interior to the Gulf, topographic slopes are gentle. The Gulf of Cadiz
is incorporated in the eastern recirculation regime ofthe North Atlantic subtropical
gyre (Siedler and Onken, 1996). It is located in the transition area between the Portugal Current and the Canary Current. A small fraction of the North Atlantic thermocline transport flows into the Strait of Gibraltar. Towards the southeast, the area
is connected to the northwest African upwelling regime. The sill depth of the Strait
of Gibraltar is about 300m at the Camarinal Sill (5°45' W). The circulation in the
strait is characterized by a near surface inflow of low salinity Atlantic Water into
the Mediterranean and an outflow of salty Mediterranean Water (MW) below.
Mean transport rates ofboth flow components are on the order of 1 Sv, mean velocities are on the order of 1 m/s. After having passed the Camarinal sill, the high
density MW slides down the continental slope and progresses further to the west
while leaning against the Spanish/Portuguese continental slope. During these
stages the MW is subject to strong mixing. The main spreading paths are confined
to two warm salinity 'veins' at about 600m and 1100m depth, typical velocities
within these veins are 40 emis or even more. The Gulf of Cadiz circulation is influenced by wind forcing and surface heat and water fluxes. In wintertime, the area
lies close to the main storm tracks of the northern hemisphere, hence wind forcing
may play a dominant role. The mean inflow/outflow situation in the Strait of
Gibraltar is superimposed by strong tidal currents, the magnitude ofwhich is on the
same order as the mean flow. Hence, within a tidal cycle, inflow/outflow may be
reversed. Special features ofthe internal dynamics ofthe region involve the external effects of internal waves and hydraulic jumps occurring in the Strait of Gibraltar within a tidal cycle, the slope convection of MW west of the Camarinal Sill and
215
tion, with its mesoscale variability, there are the wind-driven currents on the from
local and remote storms (including the Sicilian coastal current) and upwelling off
Sicily. Tides, inertial, gravity, surface, and continental shelf waves occur. This
region contains active water mass modification processes between the fresher and
warmer Atlantic origin water mass and the saltier and colder Levantine water mass.
The free jet filaments of the AIS in the Ionian Sea exhibit considerable variability
in occurrence and location as they thread their way to the Cretan passage. In addition a number of (semi-) permanent and transient sub-basin scale to mesoscale
cyclonic and anticyclonic vortices occur which are interactive with the jets and
each other. The variability of the circulation structures and sub-basin scale features
has been studied by Malanotte-Rizzoli et al (1999). Figs. 11.4 and 11.5 will be discussed in more detail below.
The Gulf of Cadiz - Fig. 11.1, introduced earlier, and Fig. 11.6 present aspects of
the circulation and topography of the Gulf of Cadiz. For our purpose we de fine the
Gulf ofCadiz as the area east of9°W and north of35°N. To the north and east it is
bounded by the Portuguese, Spanish and African coast. The western and southern
boundaries are open; another narrow open boundary exists in the east at the Strait
of Gibraltar. The west-east extension is about 270 km, in north-south direction it
extends over about 250 km. Maximum water depth is about 3000m in the southwest corner. Interior to the Gulf, topographic slopes are gentle. The Gulf of Cadiz
is incorporated in the eastern recirculation regime ofthe North Atlantic subtropical
gyre (Siedler and Onken, 1996). It is located in the transition area between the Portugal Current and the Canary Current. A small fraction of the North Atlantic thermocline transport flows into the Strait of Gibraltar. Towards the southeast, the area
is connected to the northwest African upwelling regime. The sill depth of the Strait
of Gibraltar is about 300m at the Camarinal Sill (5°45' W). The circulation in the
strait is characterized by a near surface inflow of low salinity Atlantic Water into
the Mediterranean and an outflow of salty Mediterranean Water (MW) below.
Mean transport rates ofboth flow components are on the order of 1 Sv, mean velocities are on the order of 1 m/s. After having passed the Camarinal sill, the high
density MW slides down the continental slope and progresses further to the west
while leaning against the Spanish/Portuguese continental slope. During these
stages the MW is subject to strong mixing. The main spreading paths are confined
to two warm salinity 'veins' at about 600m and 1100m depth, typical velocities
within these veins are 40 emis or even more. The Gulf of Cadiz circulation is influenced by wind forcing and surface heat and water fluxes. In wintertime, the area
lies close to the main storm tracks of the northern hemisphere, hence wind forcing
may play a dominant role. The mean inflow/outflow situation in the Strait of
Gibraltar is superimposed by strong tidal currents, the magnitude ofwhich is on the
same order as the mean flow. Hence, within a tidal cycle, inflow/outflow may be
reversed. Special features ofthe internal dynamics ofthe region involve the external effects of internal waves and hydraulic jumps occurring in the Strait of Gibraltar within a tidal cycle, the slope convection of MW west of the Camarinal Sill and