On the seasonality of waters below the seasonal thermocline in the Gulf of Cádiz
This work examines the seasonal thermohaline variability in the Gulf of Cádiz (SW Iberian Peninsula) based on 2009–2020 repeated hydrographic observations. Subsurface water types are assorted within the mixing triangle formed by Mediterranean and Eastern North Atlantic Central Waters (ENACW). A shar...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/319019 |
| Acceso en línea: | http://hdl.handle.net/10261/319019 |
| Access Level: | acceso abierto |
| Palabra clave: | Medio Marino Centro Oceanográfico de Cádiz physical oceanography seasonal thermocline thermocline seasonality continental shelves |
| Sumario: | This work examines the seasonal thermohaline variability in the Gulf of Cádiz (SW Iberian Peninsula) based on 2009–2020 repeated hydrographic observations. Subsurface water types are assorted within the mixing triangle formed by Mediterranean and Eastern North Atlantic Central Waters (ENACW). A sharp interface between 400-500 m depth separates the saline Mediterranean Overflow Waters (MOW) from the ENACW salinity minimum siting atop. The water column is warmer and more saline in winter (cooler, fresher in summer). Maximum differences of up to 0.6 ∘C and 0.15 emanate from the ENACW/MOW interface. Changes appear related to the wind-driven seasonal alternation of vertical displacement of isopycnals and poleward-equatorward transports. Upwelling-favorable winds in summer steer positive Ekman pumping velocities, which seem responsible for cooling over the ENACW salinity minimum. Below, the warm, saline signal of subtropical waters from the Azores current is attenuated by the summer approach of cooler, fresher waters from the Portugal Current system. The change of sign of Ekman pumping in winter suggests subsidence of isopycnals and warming/salinification under the seasonal thermocline. Seasonal thermohaline changes of waters leaving the Mediterranean Sea are insufficient to explain the variations under the ENACW/MOW interface. Rather, variability of Atlantic waters entrained by the overflow seem to dictate these differences. |
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