Nonhydrostatic simulations of tide-induced mixing in the Halmahera Sea: A possible role in the transformation of the Indonesian Throughflow waters
Résumé
The Indonesian Throughflow (ITF) waters are significantly transformed within the Indonesian
Archipelago and consequently influence the large-scale ocean circulation such as Agulhas and Leeuwin
Currents. Existing ocean general circulation models (OGCMs) are, however, incapable of reproducing the
transformation of the ITF waters, since tidal forcing is neglected in such models. In the present study, we
first conduct high-resolution nonhydrostatic three-dimensional numerical experiments focusing on the
transformation of the ITF waters in the Halmahera Sea which is thought to be the most important
bottleneck in simulating the ITF water mass properties. It is shown that intensive vertical mixing induced by
breaking of internal tides in the shallow regions in the Halmahera Sea dilutes the ITF waters, significantly
reducing model biases found in the existing OGCMs. We next evaluate quantitatively the effect of
tide-induced vertical mixing on the transformation of the ITF waters. It is shown that tide-induced vertical
mixing dominates the transformation of the ITF waters, although some supplementary processes such as
horizontal mixing associated with the submesoscale eddies resulting from tidal interaction with land
configurations cannot be ignored.
Domaines
Géophysique [physics.geo-ph]
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