SWOT-ACC: Smaller scales of the Antarctic Circumpolar Current in a meander south of Tasmania

Voyage Number

IN2023_V07

Voyage Dates

15 Nov, 2023 to 20 Dec, 2023

Voyage Location

Hobart to Hobart

Chief Scientist

Dr Benoit Legresy

Institution

CSIRO

View the full voyage

Voyage summary

Research voyage out of Hobart to study and understand the impact of small-scale (10-100 km) motions such as eddies on the dynamics of the Antarctic Circumpolar Current (ACC). 

The ACC is the planet's strongest current and flows from west to east around Antarctica. Importantly, it acts as a buffer between warm water to the north and the icy continent to the south, helping to keep Antarctica frozen. However, the ACC generates whirling eddies and finer scale dynamics that result in warm water seeping through this barrier towards Antarctica.

This voyage, led by CSIRO and the Australian Antarctic Program Partnership (AAPP), is seeking to understand how currents in the Southern Ocean contribute to melting Antarctic ice shelves. Scientists will study a standing meander (bend in the ocean current) in the ACC, which is a hot spot of eddy activity, cross-front exchange, and energetic small-scale motions. They will collect various ocean measurements from RV Investigator along with precise satellite measurements of sea surface height via the Surface Water Ocean Topography (SWOT) satellite. This satellite has been jointly developed by NASA and the French space agency Centre National d’Études Spatiales (CNES), and provides highly accurate sea-surface height observations at a spatial resolution at least 10x better than previously available.

Scientists aims to characterise the small-scale variability in the meander and relate small-scale variability in sea surface height to subsurface ocean structure. This will allow them to quantify the role of small-scale processes in facilitating transport of heat, carbon and energy between the surface ocean and the interior, and across the ACC. These data will help improve improve climate projections and ocean forecasts by delivering knowledge needed to better understand the influence of small-scale motions on large-scale ocean dynamics. The research will benefit a variety of end users including the Royal Australian Navy, shipping operators and managers of marine resources. 

There is 1 other project included on this voyage:

• Cloud Aerosol Precipitation Radiation Interactions eXperiment – CAPRIX_2023 (Dr Alain Protat, BOM): Collection of a suite of aerosol, cloud, surface radiation and precipitation observations.

The voyage has 34 science participants from 8 institutions including the Bureau of Meteorology (BOM), University of Tasmania, Woods Hole Oceanographic Institution (US), California Institute of Technology (US), and 20 ship crew from MMA Offshore Limited.

Voyage outcomes

A summary of voyage outcomes will be published approximately 3-6 months after the completion of the voyage.