The variability of Antarctic dense water overflows can be observed from space

Around the margins of Antarctica, dense waters formed on the continental shelf are exported to oceanic depths. This overflow of dense waters to the abyss ventilates the ocean, and is vital to the global overturning circulation. Accurately quantifying the variability in the transport of dense waters exported from the Antarctic continental shelf poses substantial challenges, due to the reliance on costly, carbon-emitting, and sparse observations or on models that do not capture complete dynamics. Here, we demonstrate that Antarctic dense water overflows can be monitored from space, using year-round sea surface height observations from satellite altimetry. We employ high-resolution simulations to characterize the sea surface height signature of the dense waters crossing the Ross Sea continental shelf break. This allows us to find a sea surface height proxy that captures the dense water transport variability, even when model outputs are subsampled to the sparse satellite observation coverage. When applied to the existing satellite record, this proxy reveals interannual variability that aligns with changes in dense water properties measured from hydrographic surveys. Our findings suggest that satellite-based monitoring can effectively complement and enhance existing in situ observing systems, by providing long-term and extensive spatial coverage of Antarctic dense water transports. Sea-surface height data from satellite altimetry can be used to capture dense water transport around Antarctica, according to high-resolution simulations of Antarctic coastal seas combined with satellite data.