Changing Southern Ocean meander drives multi-decadal atmospheric trends

AbstractWhile oceanic fronts and meanders influence the atmosphere, it remains unclear whether long-term changes in the geometry of meanders generate significant atmospheric trends. Using 26 years of satellite observations and reanalysis data, we show that the Agulhas Extension meander in the Subantarctic zone has undergone substantial geometric changes. The meander path in the western sector has become increasingly flexed and flatter in its eastern sector. These changes generate ocean surface height and temperature trends exceeding 3 cm and 0.5 °C per decade. The oceanic trends are mirrored by coherent atmospheric trends in wind speed, precipitation, and surface heat fluxes. Because the meander remains geographically fixed, its oceanic and atmospheric signatures are spatially anchored, producing localized multi-decadal trends that are 2–5 times larger than the broader regional climate trends. Our results demonstrate that gradual changes in the geometry of a standing ocean meander can drive persistent atmospheric trends, highlighting strong atmosphere–ocean coupling outside the tropics.