Open AccessWeak Mixing in the Eastern North Atlantic: An Application of the Tracer-Contour Inverse Method
Author(s) -
Jan D. Zika,
Trevor J. McDougall,
Bernadette M. Sloyan
Publication year - 2010
Publication title -
journal of physical oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.706
H-Index - 143
eISSN - 1520-0485
pISSN - 0022-3670
DOI - 10.1175/2010jpo4360.1
Subject(s) - isopycnal , thermocline , mixing (physics) , geology , tracer , geostrophic wind , inverse , inverse method , mixed layer , thermohaline circulation , climatology , geometry , mathematics , physics , quantum mechanics , nuclear physics
The tracer-contour inverse method is used to infer mixing and circulation in the eastern North Atlantic. Solutions for the vertical mixing coefficient D, the along-isopycnal mixing coefficient K, and a geostrophic streamfunction Ψ are all direct outputs of the method. The method predicts a vertical mixing coefficient O(10−5 m2 s−1) in the upper 1000 m of the water column, consistent with in situ observations. The method predicts a depth-dependent along-isopycnal mixing coefficient that decreases from O(1000 m2 s−1) close to the mixed layer to O(100 m2 s−1) in the interior, which is also consistent with observations and previous hypotheses. The robustness of the result is tested with a rigorous sensitivity analysis including the use of two independently constructed datasets. This study confirms the utility of the tracer-contour inverse method. The results presented support the hypothesis that vertical mixing is small in the thermocline of the subtropical Atlantic Ocean. A strong depth dependence of the along-isopycnal mixing coefficient is also demonstrated, supporting recent parameterizations for coarse-resolution ocean models.