Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods.

Schmidt, Christina , Schwarzkopf, Franziska U. , Rühs, Siren and Biastoch, Arne (2021) Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods. Open Access Ocean Science, 17 . pp. 1067-1080. DOI 10.5194/os-17-1067-2021.

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The inflow of relatively warm and salty water from the Indian Ocean into the South Atlantic via Agulhas leakage is important for the global overturning circulation and the global climate. In this study, we analyse the robustness of Agulhas leakage estimates as well as the thermohaline property modifications of Agulhas leakage south of Africa. Lagrangian experiments with both the newly developed tool Parcels and the well established tool Ariane were performed to simulate Agulhas leakage in the eddy-rich ocean–sea-ice model INALT20 (1/20∘ horizontal resolution) forced by the JRA55-do atmospheric boundary conditions. The average transport, its variability, trend and the transit time from the Agulhas Current to the Cape Basin of Agulhas leakage is simulated comparably with both Lagrangian tools, emphasizing the robustness of our method. Different designs of the Lagrangian experiment alter in particular the total transport of Agulhas leakage by up to 2 Sv, but the variability and trend of the transport are similar across these estimates. During the transit from the Agulhas Current at 32∘ S to the Cape Basin, a cooling and freshening of Agulhas leakage waters occurs especially at the location of the Agulhas Retroflection, resulting in a density increase as the thermal effect dominates. Beyond the strong air–sea exchange around South Africa, Agulhas leakage warms and salinifies the water masses below the thermocline in the South Atlantic.

Document Type: Article
Funder compliance: BMBF: 03F0796A
Keywords: Agulhas leakage; Indian Ocean; South Atlantic; global climate
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-OD Ocean Dynamics
Main POF Topic: PT2: Ocean and Cryosphere
Refereed: Yes
Open Access Journal?: Yes
Publisher: Copernicus Publications (EGU)
Related URLs:
Projects: SPACES-CASISAC, Advanced Earth System Modelling Capacity (ESM), Opendap
Date Deposited: 15 Apr 2021 07:45
Last Modified: 08 Feb 2023 09:31

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