On glacial-interglacial changes in the Mediterranean Outflow and its role on the Earth´s climate

• Main Authors: Pelegrí, Josep Lluís, Florindo-López, Cristián, Gasser, Marc, Peña-Izquierdo, Jesús, Emelianov, Mikhail, Ramírez, Sergio, Solé, Jordi, García-Olivares, Antonio
• Format: Conference Object
• Language: unknown
• Published: 2013
• Subjects: Passat; North Atlantic
• Online Access: http://hdl.handle.net/10261/98586

XXIX Trobades Científiques de la Mediterrània Josep Miquel Vidal: El clima de la Mediterrània: del passat als impactes del canvi climàtic = XXIX Scientific meetings of the Mediterranean Josep Miquel Vidal: Mediterranean climate: from the past to climate change impacts, 16-18 October 2013, Maó, Menorca Nowadays the Mediterranean is a source of very salty and dense water to the North Atlantic Ocean, denser than any open ocean water. If undiluted, the Mediterranean Outflow Water (MOW) would transport about 1 Sv of very salty waters to the bottom of the Atlantic Ocean. However, as the MOW plunges into the Gulf of Cádiz it undergoes very intense mixing: its salinity decreases from 38.4 at Espartel Sill to 36.5 south of Cape Santa María, after a trajectory of only some 200 km, and its transport increases by a factor of about five. This occurs through the entrainment of upper‐thermocline North Atlantic Central Waters (NACW) with salinity somewhere between 36.0 and 36.2. As a result the Mediterranean Water spreads into the North Atlantic at relatively shallow levels, with two main cores centered at depths of about 600 and 1000 m, becoming an important source of salt to the intermediate layers which may slowly diffuse toward the sea surface. Further, the shallow core is well within those depths reached by the winter mixed layer in the North Atlantic Ocean, potentially providing for a yearly salt influx of near‐surface waters. The situation probably was quite different during the Last Glacial Maximum (LGM), as the freshwater and heat balance within the Mediterranean may have substantially changed and the depth of the water column in the western end of the Strait of Gibraltar was greatly reduced. Here we first review available evidence on possible past changes in the atmospheric forcing conditions and the MOW characteristics. Based on this review we then carry out a simple sensitivity analysis. We first estimate the near‐Gibraltar salinity outflow by proposing that it responds to different Evaporation‐Precipitation ...