Renewal rates of East Atlantic deep water estimated by inversion of 14C data

• Published in: Journal of Geophysical Research
• Main Author: Schlitzer, Reiner
• Format: Article in Journal/Newspaper
• Language: English
• Published: AGU (American Geophysical Union) 1987
• Subjects: Antarctic; Antarc*; Iceland
• Online Access: https://oceanrep.geomar.de/id/eprint/32054/; https://oceanrep.geomar.de/id/eprint/32054/1/Schlitzer.pdf; https://doi.org/10.1029/JC092iC03p02953

The renewal of the deep water of the East Atlantic and its large-scale internal circulation are studied on the basis of the distributions of potential temperature, silicate, ΣCO2, and 14C. An isopycnal multibox model including advection, mixing, and sources and sinks is set up and described. Tracer data are input for the model, and balance equations for the various properties for the boxes of the model serve as constraints for the determination of water fluxes, mixing coefficients, and source parameters. Extremal values for various model parameters that are consistent with the tracer data (satisfy the balance equations within the estimated tolerances) are calculated by linear programming techniques. 14C data are seen to be valuable in determining absolute flow rates. Model results confirm the importance of the Romanche Facture Zone for the renewal of east Atlantic deep water. Eastward flows through the Romanche Fracture Zone were found to be between 2.6 and 5.1 Sv. Flows through the Vema Fracture Zone amount to at most 20% of the Romanche Fracture Zone inflow. Contributions of Antarctic Bottom Water at the southern end of the East Atlantic (Walvis Ridge) and of Iceland Scotland Overflow Water at the northern end are very small (< 5% of equatorial inflow). Diapycnal mixing coefficients are between 1 and 10 cm2/s, and values for the dissolution rates of silicate and carbon are in the expected range.