A Geodetic Analysis of the Volume Transport in the ACC Region Based on Satellite Data

Abstract

Geostrophic currents, driven by the Coriolis and pressure gradient forces, are crucial for understanding ocean circulation. The Antarctic Circumpolar Current (ACC) in the Southern Ocean, which surrounds Antarctica, has a significant global impact, and its volume transport (VT) remains a challenge to measure. We use satellite data, combining altimetry and gravity satellite missions, to estimate VT within the ACC region. Our study provides a comprehensive spatial and temporal analysis, including both barotropic and baroclinic VT components. The spatial analysis reveals a mean VT of 210.44 ± 3.4 Sv for the entire study area, with maxima near critical choke points. Focusing on the time-varying component, we identify a mean VT of 15.86 ± 0.05 Sv per 1° grid cell, a linear trend of −0.007 ± 0.002 Sv per month, and significant seasonal and biannual signals. The baroclinic component drives low-frequency variability, while the barotropic component controls high-frequency variability. We propose a specific ACC zonal VT of 201.63 ± 0.71 Sv. We validate our results with in situ measurements from the Drake Passage. In conclusion, our satellite-based approach provides valuable insights into the ACC VT. This methodological extension improves our understanding of the ocean circulation dynamics of the ACC and demonstrates the utility and robustness of satellite data in oceanographic research.