A Lagrangian Estimate of the Mediterranean Outflow's Origin

• Published in: Geophysical research letters Vol. 50; no. 14
• Main Authors: Vecchioni, G., Cessi, P., Pinardi, N., Rousselet, Louise, Trotta, F.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.07.2023; American Geophysical Union; Wiley
• Subjects: Deep water; Intermediate water; Intermediate water masses; Lagrangian analysis; Mediterranean outflow; Mediterranean water masses; Momentum; Ocean circulation; Ocean circulation models; Ocean currents; Ocean models; Outflow; Salinity; Sciences of the Universe; Straits; Transit time; Transport; Velocity; Velocity estimation; Water circulation; Water masses; Mediterranean Sea; Strait of Gibraltar; Mediterranean water masses; Lagrangian analysis; Mediterranean outflow
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL103699

The origin of the Mediterranean Outflow is investigated by deploying six millions virtual Lagrangian parcels at the Strait of Gibraltar, and tracing them backward in time using velocity estimates from an eddy‐permitting reanalysis. The Lagrangian parcels are followed until they intercept one of three sections. The hypothesis is that each section is associated with distinct water masses: the Gulf of Lions, related to Western Mediterranean Deep Water and Western Intermediate Water, carries 86% of the Outflow's transport; the Northern Tyrrhenian, related to Tyrrhenian Deep and Intermediate Waters, carries 1% of the transport; the Strait of Sicily, related to Levantine Intermediate Waters, carries 13% of the transport. The median transit times from the sections to the Strait of Gibraltar range from 5 years (Gulf of Lions) to 8 years (Strait of Sicily). Plain Language Summary Parcel trajectories are used to trace water masses from the Western Mediterranean Sea to the Mediterranean Sea outflow at the Strait of Gibraltar. The velocity advecting the parcels is an estimate combining observations with an ocean circulation model that conserves mass, momentum, temperature and salinity. It is found that 86% of the parcels in the Mediterranean Sea outflow originate from the Gulf of Lions, typically taking 5 years for the journey, while 13% originates from the Strait of Sicily, typically taking 8 years to complete the trip. Key Points Eighty‐six percent of Mediterranean outflow originates from the Gulf of Lions, and 13% originates from the Strait of Sicily These two components of the outflow have distinct T‐S distributions at the origin, but the distinction is lost when Gibraltar is reached Median transit times to the Strait of Gibraltar are 5 years from the Gulf of Lions and 8 years from the Strait of Sicily