Using Sea Level to Determine the Strength, Structure and Variability of the Cape Horn Current

The Cape Horn Current (CHC) is one of the components of the Antarctic Circumpolar Current system that enables it to fulfill its crucial role as a conduit between ocean basins. Despite this, to-date there have been very few measurements of CHC strength and none continuous in time or space. Here, we use a combination of ocean models, one free-running and one data-assimilating, and satellite altimetry (1993–2021) to estimate the time-dependent strength of the CHC at 10 transects along its length. We find the time-mean CHC transport increases from 0.4 ± 0.5 Sv near 49°S to 5.3 ± 2.2 Sv at Cape Horn, with peak-to-peak interannual fluctuations of 0.8–3.4 Sv. Although, theoretically, increased run-off from a wasting Patagonian Ice-field would strengthen its flow, the CHC appears quite stable over the last 29 years, with little evidence of a coherent, long-term increase or decrease in the strength of the current.