Wind induced variability of hydrographic features and water masses distribution in the Gulf of Cadiz (SW Iberia) from in situ data

In May–June 2001, the GOLFO 2001 survey was carried out in the Gulf of Cadiz area (South-West Iberia). The survey consisted of three legs that were accomplished under different wind regimes. In Mesoscale 1 (under westerlies) North Atlantic Central Water was located in the northern region and Surface Atlantic Water in the outer part and this distribution maintained for the entire upper water column, with the only exception of some traces of Shelf Water in the surface layer closest to the Guadalquivir river mouth. In Mesoscale 2 (under easterlies), Shelf Water was advected westwards by the coastal countercurrent that developed under this regime, thus flooding the surface layer of the eastern (and partly the western) continental shelf and restricting the upwelled North Atlantic Central Water to a smaller region west of 8°W. This pattern only affects the upper 20–25 m of the water column, then recovering the common distribution with North Atlantic Central Water in the northern area and Surface Atlantic Water in the outer part of the basin. The wind induced variability modified the surface TS diagrams and these variations have been used to further investigate the water masses distribution in terms of the TS properties of three “standard” points defined on the TS diagram.