2024-03-28T16:04:12Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/569982020-05-25T12:46:11Zcom_10261_47com_10261_8col_10261_300
Surface waters of the NW Iberian margin: Upwelling on the shelf versus outwelling of upwelled waters from the Rías Baixas
Álvarez-Salgado, Xosé Antón
Gago, Jesús
Martín Míguez, Belén
Gilcoto, Miguel
Pérez, Fiz F.
Upwelling
Downwelling
Outwelling
Box models
Spanish rias
17 páginas, 1 apéndice, 7 figuras, 3 tablas
A set of hydrographic surveys were carried out in the Ría of Vigo (NW Spain) at 2–4 d intervals during four 2–3 week
periods in 1997, covering contrasting seasons. Residual exchange fluxes with the adjacent shelf were estimated with a
2-D, non-steady-state, salinity–temperature weighted box model. Exchange fluxes consist of a steady-state term
(dependent on the variability of continental runoff) and a non-steady-state term (dependent on the time changes of
density gradients in the embayment). More than 95% of the short-time-scale variability of the exchange fluxes in the
middle and outer rı´a can be explained by the non-steady-state term that, in turns, is correlated (R2>75%) with the
offshore Ekman transport. Conversely, 96% of the variability of exchange fluxes in the inner rı´a rely on the steady-state
term. The outer and middle rı´a are under the direct influence of coastal upwelling, which enhances the positive residual
circulation pattern by an order of magnitude: from 102 to 103 m3 s 1. On the contrary, downwelling provokes a reversal
of the circulation in the outer rı´a. The position of the downwelling front along the embayment depends on the relative
importance of Ekman transport (Qx, m3 s 1 km 1) and continental runoff (R, m3 s 1). When Qx/R>7 2 the reversal
of the circulation affects the middle rı´a. Our results are representative for the ‘Rı´as Baixas’, four large coastal indentations
in NW Spain. During the upwelling season (spring and summer), 60% of shelf surface waters off the ‘Rı´as Baixas’ consist
of fresh Eastern North Atlantic Central Water (ENACW) upwelled in situ. The remaining 40% consists of upwelled
ENACW that previously enters the rı´as and it is subsequently outwelled after thermohaline modification. During the
downwelling season (autumn and winter), 40% of the warm and salty oceanic subtropic surface water, which piled on the
shelf by the predominant southerly winds, enters the rías.
Financial support for this work came from
CICYT Grant No. AMB95-1084.
Peer reviewed
2012-10-01T11:05:27Z
2012-10-01T11:05:27Z
2000
artículo
http://purl.org/coar/resource_type/c_6501
Estuarine, Coastal and Shelf Science 51(6): 821-837 (2000)
0272-7714
http://hdl.handle.net/10261/56998
10.1006/ecss.2000.0714
en
http://dx.doi.org/10.1006/ecss.2000.0714
open
Elsevier