Standing Meanders of the Antarctic Circumpolar Current: Evidence for Ridge‐Controlled Eddy Saturation

The standing meanders of the Antarctic Circumpolar Current are key sites of mixing and meridional transport in the Southern Ocean, but their long‐term variability and trends remain poorly understood. Here, we investigate the Pacific‐Antarctic Ridge meander using satellite altimetry data from 1993 to 2023. While its mean position has remained broadly stable, the meander has widened by 1.44 km per decade and accelerated by 0.01 m per decade, with the largest changes concentrated downstream of the first meander trough. Analysis indicates that the dominant contributor to these trends is a multi‐decadal increase in eddy kinetic energy, reflecting enhanced along‐jet variability and intensified eddy‐mean flow interactions. A secondary but coherent influence arises from upper‐ocean warming, which strengthens meridional thermal gradients and is consistent with a barotropic‐baroclinic acceleration of the jet. Additional contributions include modest poleward shifts and intensification of westerly winds, and a basin‐scale strengthening of the South Pacific Gyre that reinforces the downstream acceleration. The Pacific‐Antarctic Ridge meander exhibits structural changes distinct from those documented over the Campbell Plateau, highlighting regional contrasts in standing‐meander sensitivity to forcing. These findings carry implications for cross‐frontal exchange, jet stability, and the evolving dynamical role of the Southern Ocean in the global climate system.