Velocities (cm/s) at surface and bottom layers averaged during a tidal cycle under persistent
winds.
Light easterly
winds
Moderate easterly winds
Cruise
April
14-15
Mav
26-27
February
10-11 *
February
24-25
March
10-11
March
24-25
Average velocity at surface
layers (0-7 m)
0.7
-0.5
-5.8
-5.1
4.1
-7.1
Average velocity 7 at bottom
layers (19-26 m)
-0.9
-1.1
0.5
0.9
0.8
1.0
Conclusion
The hydrodynamical characteristics of the Ría de Pontevedra were studied
from Febmaty to July 1998. At an anchored station, hydrodynamical
samples were taken during a tidal period at night. Due to the estuary
morphology, the transversal component of current speed was observed
to be negligible.
From cruises described above, we can conclude that there is a clear predominance of winds in the main estuary axis direction. Wind measurements sho )w that wind direction strongly depends on topography.
Wind speeds higher than 4 m.s
1 are able to dominate the current pattern
at surface layers. In this case, the current speed induced by wind is bigger
than the one induced by tide. Easterly winds were observed in most of the
cruises during the whole night while westerly winds were measured in
some cmises and at certain time intervals coinciding with the existence of
breezes or the presence of a low pressure front on the shelf. Easterly winds
higher than 4 ms' force water to leave the estuary through surface layers
while westerly winds force water to enter the estuary. Bottom layers were
observed to be mainly controlled by tide. Finally, diumal breeze effects
could only be measured during the cmises June 9-10 and June 23-24)
carried out under diumal air temperatures reaching 25°C and a stable
atmospheric situation.
Acknowledgments
This work was partially supported by Comisiôn Interministerial de Ciencia y Tecnologta, under project MAR96-1782. We also want to acknowledge the Marin Harbour
Institute, especiallv F. Linaje and H. Abati, for their inestimable help with wind data.
Bibliographic references
Blanton J.O., Tenorc K.R., Castillejo F., Atkinson L.P., Schwing F.B.,
Lavin A., 1987. The relationship of upwelling to mussel production
in the rias on the western coast of Spain. J. Mar. Res., 45, 79-90.
273
winds.
Light easterly
winds
Moderate easterly winds
Cruise
April
14-15
Mav
26-27
February
10-11 *
February
24-25
March
10-11
March
24-25
Average velocity at surface
layers (0-7 m)
0.7
-0.5
-5.8
-5.1
4.1
-7.1
Average velocity 7 at bottom
layers (19-26 m)
-0.9
-1.1
0.5
0.9
0.8
1.0
Conclusion
The hydrodynamical characteristics of the Ría de Pontevedra were studied
from Febmaty to July 1998. At an anchored station, hydrodynamical
samples were taken during a tidal period at night. Due to the estuary
morphology, the transversal component of current speed was observed
to be negligible.
From cruises described above, we can conclude that there is a clear predominance of winds in the main estuary axis direction. Wind measurements sho )w that wind direction strongly depends on topography.
Wind speeds higher than 4 m.s
1 are able to dominate the current pattern
at surface layers. In this case, the current speed induced by wind is bigger
than the one induced by tide. Easterly winds were observed in most of the
cruises during the whole night while westerly winds were measured in
some cmises and at certain time intervals coinciding with the existence of
breezes or the presence of a low pressure front on the shelf. Easterly winds
higher than 4 ms' force water to leave the estuary through surface layers
while westerly winds force water to enter the estuary. Bottom layers were
observed to be mainly controlled by tide. Finally, diumal breeze effects
could only be measured during the cmises June 9-10 and June 23-24)
carried out under diumal air temperatures reaching 25°C and a stable
atmospheric situation.
Acknowledgments
This work was partially supported by Comisiôn Interministerial de Ciencia y Tecnologta, under project MAR96-1782. We also want to acknowledge the Marin Harbour
Institute, especiallv F. Linaje and H. Abati, for their inestimable help with wind data.
Bibliographic references
Blanton J.O., Tenorc K.R., Castillejo F., Atkinson L.P., Schwing F.B.,
Lavin A., 1987. The relationship of upwelling to mussel production
in the rias on the western coast of Spain. J. Mar. Res., 45, 79-90.
273