Geostropic Currents in the Southern Ocean: ACC and Drake Passage Volume Transport
Event: 2020 Ocean Surface Topography Science Team Meeting (virtual)
Session: The Geoid, Mean Sea Surfaces and Mean Dynamic Topography
Presentation type: Type Forum
The 3D geostrophic currents and the associated volume transport (VT) can be estimated from the GOCE and Altimetry satellite data and in-situ temperature and salinity profiles measured by the Argo floats. We updated an earlier approach by Vigo et al. (2018) for the Southern Ocean between 20º S and 65º S with their time variability over the 12-year period of 2004-2015. In this new approach, we used the DTUUH19MDT, and integrate down to 3900 m. The results depict the Southern Ocean circulation where a zonal Antarctic Circumpolar Current (ACC) interacts with a meridional thermohaline circulation. The VT reproduces the polar front and the subantarctic front of the ACC, as well as the large scale and mesoscale currents in the Southern Ocean. For ACC, the estimated VT at the Drake Passage is 136.7 Sv for the mean of the norms of the monthly VT, which is closer than previous estimation to observations (ranging from 134 to 175 Sv). The spatially averaged ACC VT shows per 1\degree width in the main stream a mean value of 16.96 Sv being mainly zonal. Water transports of barotropic and baroclinic origin have been isolated in the VT series showing that 24.19% of transport is barotropic and the remaining 75.81% baroclinic, while the variability and annual signal in the ACC is fully barotropic.