A transatlantic tritium section near 40°N, 1971

• Main Authors: Roether, Wolfgang, Weiss, Wolfgang
• Format: Article in Journal/Newspaper
• Language: English
• Published: Bornträger 1978
• Subjects: Arctic; North Atlantic; Subarctic
• Online Access: https://oceanrep.geomar.de/id/eprint/56405/; https://oceanrep.geomar.de/id/eprint/56405/1/Roether_W_1978_A.pdf

We report, numerically and in graphical form, measured tritium concentrations from five hydrographic stations in the North Atlantic. Fairly homogeneous concentrations are observed in a surface layer typically 400 m deep. In the thermocline, concentrations decrease steadily down to the a σθ = 27.3 density horizon, and are more variable further down. The tritium in the lower part of the thermocline originates from the Subarctic Intermediate Water and the Mediterranean Water. There is a relative tritium maximum associated with the Mediterranean Water on the easternmost station of the section. In the deep water (σθ > 27.8), concentrations east of the Midatlantic Ridge are close to the limit of detection down to 2500 m, and undetectable further down, while west of the ridge tritium is found throughout the water column. The deep water tritium is associated with the deep-water advective cores of Arctic origin. The present tritium data can serve as northern boundary values in attempts to use tritium in studies of the North Atlantic main thermocline dynamics. The present data together with data from the literature point to a general division of the North Atlantic main thermocline into two layers separated by an isopycnal surface near σθ = 27.3.