Characteristics and Trends of the Pacific-Antarctic Ridge Meander in the Southern Ocean: 1993-2023

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 s-1 per decade, with the largest changes concentrated downstream of the first meander trough. We provide analysis to link these trends to enhanced eddy kinetic energy, intensification of westerly winds, subsurface ocean warming, and the basin-scale strengthening of the South Pacific Gyre. Similar patterns have been observed in the standing meanders of the Campbell Plateau and Agulhas Extension, suggesting that widening and acceleration are common features of Southern Ocean standing meanders. These structural changes have important implications for cross-frontal exchange, eddy-mean flow interactions, and the role of the Southern Ocean in global climate.