generated by the internal tide with an amplitude of 45 m. The estimated energy
fluxes were 2 kW m
−1 . Note for comparison that the energy fluxes associated with
the strongest internal tides in the South China Sea are as high as 40 kW m
−1 [11].
Very strong internal tides are generated over the continental slope on the
northern coast of Biscay Bay [12]. Our analysis is based on the archived moored
measurements gathered in the Iberian Basin during many expeditions within different oceanographic programs. We use the clusters of moorings as an antenna to
estimate the direction of the internal tides and their wavelength. The method of
calculation is based on the calculation of the spatiotemporal spectrum. A line of
moorings normal to the slope can be helpful to estimate the decay of internal tides.
Solitary moorings distributed over large regions can be used to evaluate the geographical distribution of the internal tide energy.
Analysis of the internal tides in the Strait of Gibraltar was carried out in [5]. The
flow in the strait is characterized by a two-layer system of opposite currents
resulting from the difference in sea level and water density (salinity and temperature) between the Atlantic Ocean and the Mediterranean Sea. The flow changes its
direction approximately at a depth of 100 m. The barotropic tidal wave with mean
velocities in the range 70–80 cm/s propagates through the strait. The barotropic tide
generates an internal tidal wave, when the tidal currents flow over the Camarinal
Sill located in the middle of the Strait of Gibraltar. Extreme tidal internal waves
(with an amplitude reaching 160 m) are observed only over the Camarinal Sill. The
vertical displacement of the 13 C isotherm ranges from 100 to 300 m. When the
internal tide wave reaches the western part of the Strait of Gibraltar, its amplitude in
the open ocean decreases to 30 m, which is comparable with the amplitudes of
internal tides generated on the continental slopes of Iberia and Africa.
The wavelength of the internal tide propagating to the east ranges from 90 to
140 km, while the wavelength of the internal tide propagating to the west ranges
from 45 to 60 km. The wavelength of the internal tide propagating in the eastern
direction is greater and the difference is not surprising because the depths east of the
Camarinal Sill are greater than in the western part of the Strait.
The Data
Many moorings were deployed in the region in the last 30 years. During the World
Ocean Circulation Experiment (WOCE), two lines of moorings were deployed in
1993–1994 on the continental slope of the Iberian Peninsula as part of the Multidisciplinary Oceanographic Research in the Eastern Boundary of the North
Atlantic project (MORENA).
The lines included three moorings ACM-27 (along 42° 16′ N) and four ACM-28
moorings along 41° 00′ N from 9° 30′ W to 11° 00′ W (Fig. 1). These measurements were intended to study the processes on the continental slope.
In 1988, the oceanographers onboard the Russian R/V “Vityaz” studied the
spreading of Mediterranean Water from the Strait of Gibraltar to the Atlantic Ocean
184
E. G. Morozov and M. G. Velarde
fluxes were 2 kW m
−1 . Note for comparison that the energy fluxes associated with
the strongest internal tides in the South China Sea are as high as 40 kW m
−1 [11].
Very strong internal tides are generated over the continental slope on the
northern coast of Biscay Bay [12]. Our analysis is based on the archived moored
measurements gathered in the Iberian Basin during many expeditions within different oceanographic programs. We use the clusters of moorings as an antenna to
estimate the direction of the internal tides and their wavelength. The method of
calculation is based on the calculation of the spatiotemporal spectrum. A line of
moorings normal to the slope can be helpful to estimate the decay of internal tides.
Solitary moorings distributed over large regions can be used to evaluate the geographical distribution of the internal tide energy.
Analysis of the internal tides in the Strait of Gibraltar was carried out in [5]. The
flow in the strait is characterized by a two-layer system of opposite currents
resulting from the difference in sea level and water density (salinity and temperature) between the Atlantic Ocean and the Mediterranean Sea. The flow changes its
direction approximately at a depth of 100 m. The barotropic tidal wave with mean
velocities in the range 70–80 cm/s propagates through the strait. The barotropic tide
generates an internal tidal wave, when the tidal currents flow over the Camarinal
Sill located in the middle of the Strait of Gibraltar. Extreme tidal internal waves
(with an amplitude reaching 160 m) are observed only over the Camarinal Sill. The
vertical displacement of the 13 C isotherm ranges from 100 to 300 m. When the
internal tide wave reaches the western part of the Strait of Gibraltar, its amplitude in
the open ocean decreases to 30 m, which is comparable with the amplitudes of
internal tides generated on the continental slopes of Iberia and Africa.
The wavelength of the internal tide propagating to the east ranges from 90 to
140 km, while the wavelength of the internal tide propagating to the west ranges
from 45 to 60 km. The wavelength of the internal tide propagating in the eastern
direction is greater and the difference is not surprising because the depths east of the
Camarinal Sill are greater than in the western part of the Strait.
The Data
Many moorings were deployed in the region in the last 30 years. During the World
Ocean Circulation Experiment (WOCE), two lines of moorings were deployed in
1993–1994 on the continental slope of the Iberian Peninsula as part of the Multidisciplinary Oceanographic Research in the Eastern Boundary of the North
Atlantic project (MORENA).
The lines included three moorings ACM-27 (along 42° 16′ N) and four ACM-28
moorings along 41° 00′ N from 9° 30′ W to 11° 00′ W (Fig. 1). These measurements were intended to study the processes on the continental slope.
In 1988, the oceanographers onboard the Russian R/V “Vityaz” studied the
spreading of Mediterranean Water from the Strait of Gibraltar to the Atlantic Ocean
184
E. G. Morozov and M. G. Velarde