| Summary: | Oceanic macroturbulence is efficient at stirring and transporting tracers. The dynamical properties of this stirring can be characterized by statistically quantifying tracer structures. Here, we characterize the macroscale (1–100km) tracer structures observed by two Seagliders downstream of the Southwest Indian Ridge in the Antarctic Circumpolar Current (ACC). These are some of the first glider observations in an energetic standing meander of the ACC, a region associated with enhanced ventilation. The small-scale density variance in the mixed layer (ML) was relatively enhanced near the surface and base of the ML, while being muted at mid-depth in the ML, suggesting the formation mechanism to be associated with ML instabilities and eddies. In addition, ML density fronts were formed by comparable contributions from temperature and salinity gradients. In the interior, along-isopycnal spectra and structure functions of spice indicated that there is relatively lower variance at smaller scales than would be expected based on non-local stirring, suggesting that flows smaller than the deformation radius play a role in the cascade of tracers to small scales. These interior spice anomalies spanned across isopycnals, and were found to be about 3–5 times flatter than the aspect ratio that would be expected for O(1) Burger number flows like interior QG dynamics, suggesting the ratio of vertical shear to horizontal strain is greater thanN/f. This further supports that small-scale flows, with high-mode vertical structures, impact tracer distributions. © 2024 The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes This work was made possible by the National Science Foundation under Grant 2102495. We thank the Incorporated Research Institutions for Seismology, whose internship program allowed Tamama to pursue this ...
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