Characteristics and Trends of the Campbell Plateau Meander in the Southern Ocean: 1993–2020

Abstract

AbstractMeanders are significant features of the Antarctic Circumpolar Current in the Southern Ocean and sites of enhanced upwelling, cross‐frontal tracer fluxes, and exchanges between the surface and deep ocean. They often overlap the locations of fronts and are linked to topographic features. While much is known about Southern Ocean fronts and how they are changing, the response of meanders to climate change is largely unexplored. In this study, we investigate the Campbell Plateau meander south of New Zealand. We apply a local gradient maxima method to satellite altimetry data to identify the position of the meander and estimate its width, geostrophic current speed, and associated trends from 1993 to 2020. We find that the position of the meander has been relatively fixed, except for a section downstream of the Plateau, which has shifted northward by about 0.4° latitude per decade. The meander has become flatter at the western edge of the Plateau, but steeper at the eastern edge of the Plateau. Overall, the meander has widened by 2 km per decade and accelerated by 0.01 m s−1 per decade, particularly downstream of the Plateau. These findings are consistent with other work on standing meanders in the Southern Ocean. Increases in eddy kinetic energy and of the South Pacific Gyre index support our hypotheses that changes in the downstream jet stability and the South Pacific Gyre contribute to these observed trends. The impacts of these trends on cross‐frontal transport remain to be evaluated.