Regional circulation patterns of Mediterranean Outflow Water near the Iberian and African continental slopes

Abstract

Abstract. The Mediterranean Outflow Water (MOW) is a dense water mass originated in the Strait of Gibraltar. Downstream of the Gulf of Cádiz, the MOW forms a reservoir region west of the Iberian continental slopes at a buoyant depth of approximately 1000 m. This region plays a key role as the main centre where the MOW is mixed and distributed into the North Atlantic. The seafloor in this area is characterized by the presence of a complex bathymetry with three abyssal plains separated by mountain chains. Although the topographic features do not reach the surface, they influence ocean flows at intermediate and deep ocean layers, conditioning the distribution and circulation of MOW. The Copernicus Marine Environmental Monitoring Service (CMEMS) Iberian–Biscay–Ireland (IBI) ocean reanalysis is used to provide a detailed view of the circulation and mixing processes of MOW near the Iberian and African continental slopes. This work emphasizes the relevance of the complex bathymetric features defining the circulation processes of MOW in this region. The high resolution of the IBI reanalysis allows us to make a description of the mesoscale features forced by the topography. The temperature, salinity, velocity, transport, and vorticity fields are analysed to understand the circulation patterns of MOW. The high-resolution circulation patterns reveal that Horseshoe Basin and the continental slope near Cape Ghir (a.k.a. Cap Rhir or Cabo de Aguer) are key areas controlling the mixing processes of MOW with the surrounding water masses, mainly North Atlantic Central Water (NACW) and Antarctic Intermediate Water (AAIW). The water mass variability is also analysed by means of composite analysis. Results indicate the existence of a variability in the MOW tongue which retracts and expands westwards in opposition to the movement of the underlying North Atlantic Deep Water.

A New Messinian 87Sr/86Sr Curve for the Ain El Beida Section (Morocco): An Atlantic Perspective of the Mediterranean Salinity Crisis

“…A possible impact of the Mediterranean outflow and its periodical changes on the Moroccan Atlantic margin during the Messinian cannot be discarded. However, the present‐day outflow runs mainly to the northwest, along the Iberian Atlantic margin, at a depth of around 1,000 m (Hernández‐Molina et al., 2014, 2016); only a limited part of the outflow spreads to the southwest along the African margin (de Pascual‐Collar et al., 2019). The circulation pattern is strongly controlled by the geometry and size of the Atlantic gateway area, which is virtually unknown for the Messinian interval.…”

Heat content and temperature trends in the Mediterranean Sea as derived from Argo float data

“…o r g / M W M _ A c r o n y m s / MedWaterMassAcronyms.pdf). The heat gain in the MIW (0.019 ± 0.007°Cyr -1 , see Table 3) and in particular in the Western Intermediate Water (WIW, https://ciesm.org/MWM_Acronyms/ MedWaterMassAcronyms.pdf) of 0.019 ± 0.007°Cyr -1 also provides information about the warming of the Mediterranean Outflow Waters (MOW), the saline and warm water mass located in the intermediate depths of the North Atlantic and produced by the outflow of Mediterranean water through the Strait of Gibraltar (Millot et al, 2006;Naranjo et al, 2015;de Pascual-Collar et al, 2019). This water mass is one of the most important intermediate water masses in the North Atlantic; it is involved in the North Atlantic Deep Water formation processes and its properties and variability have a significant impact on global climate (Aldama-Campino and Döös, 2020).…”

On the Representation of Mediterranean Overflow Waters in Global Climate Models

“…It reaches neutral buoyancy and geostrophic balance at 78W and 800-1200-m depth in the Gulf of Cádiz (GoC; Fig. 1, Ochoa and Bray 1991;Price et al 1993;Sánchez-Leal et al 2017;de Pascual-Collar et al 2019). After exiting the narrow SoG (14.5 km wide and approximately 280 m deep), bathymetry has a strong impact on the MOW's composition and pathways and determines its integration with other Atlantic water masses (Sánchez-Leal et al 2017).…”