Water circulation induced by the wind
in the inner part of a Galician rîa (NW Spain):
winter and spring situations
Maitc Dc Castro
(1,2) , Moncho Gômez Cîcsteira
(1 ’
2) , Ricardo Prego
(3) ,
JuanJosé Taboada
(l) , Pcdro Montero
(1) , Vicente Pércz Villar
(1)
(1) Umversidad de Santiago de Compostela, Facultad de Fîsica, Grupo de Fisica no Lineal,
15706 Santiago, Espaiîa
(2) Universidad de Vigo, Facultad de Ciencias, Dpto Fisica Aplicada, Campus de Ourense,
Espana
(3) Instituto de Investigaciones Marinas, CSIC, Vigo, Espana.
uscfmmcr@cesga.es
Abstract
Thc wind effect on water circulation was described by means of hydrodynamical measuremcnts carried out in the Ría de Pontevedra (NW of
Spain) from February to July 1998. The samples wcre mcasured at an
anchored station situated in the inner part of the ría. It was observed a
clear predominance of wind in the main estuaty axis direction. Wind
speeds higher than 4 m.s -1 arc ablc to dominate the current at surfacc
layers. Easterly winds forcc water to leave the cstuarv at surfacc layers
whilc westerly winds force water to enter it.
Introduction
The Rias Baixas are located in thc NW of thc Iberian Peninsula. These
rias behavc as partially mixed cstuaries with a two-layered residual circulation pattern (Prcgo & Fraga, 1992). They are characterized by a mesotidal
and a semidiumal tide which is the main factor of their dynamics. T)piical tidal amplitudes of 2 m and 3 m were measured during neap and
spring tides, respectively. In the Rias Baixas, upwelling c\
r ents occur
from April to October (Blanton et al, 1987) when the average winds
along the coast exert a southward surface stress causing an Ekman
transport offshore. Thc tide, the freshwater contribution, the wind regime in the rias and the upwelling events control the water exchange
betv'ccn thc rfas and the shelf.
Duc to their economical activit\
T , the Rias Baixas have been extensively
studied both by means of in situ measurements (Prego, 1990; Fraga,
1996) and by numerical models (Bermüdez et aL, 1996; Taboada et al,
1998; ( kkncz Gesteira et at, 1999).
The aim of this paper is to make a description of thc currents measured
in thc inner part of the Rîa de Pontevedra from Februarj' to July 1998
to study thc wind effects on water circulation. /\n anchored station was
considered in order to measurc currents (fig. 1).
268
in the inner part of a Galician rîa (NW Spain):
winter and spring situations
Maitc Dc Castro
(1,2) , Moncho Gômez Cîcsteira
(1 ’
2) , Ricardo Prego
(3) ,
JuanJosé Taboada
(l) , Pcdro Montero
(1) , Vicente Pércz Villar
(1)
(1) Umversidad de Santiago de Compostela, Facultad de Fîsica, Grupo de Fisica no Lineal,
15706 Santiago, Espaiîa
(2) Universidad de Vigo, Facultad de Ciencias, Dpto Fisica Aplicada, Campus de Ourense,
Espana
(3) Instituto de Investigaciones Marinas, CSIC, Vigo, Espana.
uscfmmcr@cesga.es
Abstract
Thc wind effect on water circulation was described by means of hydrodynamical measuremcnts carried out in the Ría de Pontevedra (NW of
Spain) from February to July 1998. The samples wcre mcasured at an
anchored station situated in the inner part of the ría. It was observed a
clear predominance of wind in the main estuaty axis direction. Wind
speeds higher than 4 m.s -1 arc ablc to dominate the current at surfacc
layers. Easterly winds forcc water to leave the cstuarv at surfacc layers
whilc westerly winds force water to enter it.
Introduction
The Rias Baixas are located in thc NW of thc Iberian Peninsula. These
rias behavc as partially mixed cstuaries with a two-layered residual circulation pattern (Prcgo & Fraga, 1992). They are characterized by a mesotidal
and a semidiumal tide which is the main factor of their dynamics. T)piical tidal amplitudes of 2 m and 3 m were measured during neap and
spring tides, respectively. In the Rias Baixas, upwelling c\
r ents occur
from April to October (Blanton et al, 1987) when the average winds
along the coast exert a southward surface stress causing an Ekman
transport offshore. Thc tide, the freshwater contribution, the wind regime in the rias and the upwelling events control the water exchange
betv'ccn thc rfas and the shelf.
Duc to their economical activit\
T , the Rias Baixas have been extensively
studied both by means of in situ measurements (Prego, 1990; Fraga,
1996) and by numerical models (Bermüdez et aL, 1996; Taboada et al,
1998; ( kkncz Gesteira et at, 1999).
The aim of this paper is to make a description of thc currents measured
in thc inner part of the Rîa de Pontevedra from Februarj' to July 1998
to study thc wind effects on water circulation. /\n anchored station was
considered in order to measurc currents (fig. 1).
268