Open AccessHydrography of the Pontevedra Ria: Intra‐annual spatial and temporal variability in a Galician coastal system (NW Spain)
Author(s) -
Prego Ricardo,
Dale Andrew W.,
deCastro Maite,
GómezGesteira Moncho,
Taboada Juan J.,
Montero Pedro,
Villareal Manuel R.,
PérezVillar Vicente
Publication year - 2001
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000jc000775
Subject(s) - upwelling , hydrography , oceanography , geology , discharge , current (fluid) , continental shelf , salinity , water mass , water column , surface runoff , surface water , environmental science , climatology , geography , drainage basin , ecology , cartography , biology , environmental engineering
In order to ameliorate the dearth of existing scientific knowledge concerning the hydrography of the Pontevedra Ria, a systematic investigation was carried out between October 1997–98. Salinity variations were closely related to river discharge whereas bottom waters presented oceanic characteristics over the whole year. Current was controlled by tide, river discharge, and wind in the internal ria where the highest velocities were directed along the ria channel with a low transverse component. Favorable atmospheric conditions in spring induced coastal upwelling up the continental shelf. In May the upwelling was sufficiently strong to be detected in the inner ria and intensified in July and August, cooling the ria water to 12°–14°C. Upwelling ceased in September, and from November to March seawater transported by the poleward current (35.9; 15°C) was detected on the shelf. From January until March, unanticipated favorable upwelling conditions provoked an influx of poleward inside the ria. Ria intrusion of poleward water and association with occasional winter upwelling conditions has not been observed previously. Isopycnic three‐dimensional (3‐D) surface and 2‐D isopycnal maps show that with high river runoff or intense upwelling, lower‐salinity water leaves the ria near the northern margin in the surface layer. Under negative upwelling conditions, the water is partially dammed inside the ria and exits the ria when the wind speed falls. During upwelling events, ENACW penetrated the ria, especially near the southern shore. Arrival of ENACW at the northern entrance impedes the outward water flow through this mouth.