Project overview

Schematic of the Weddell Gyre and ANDREX and WOCE hydrographic sections.
Schematic of the Weddell Gyre and ANDREX and WOCE hydrographic sections. ©

The ANDREX programme aims to enhance our understanding of the role of the Weddell Gyre in

  1. driving the southern closure of the Meridional Overturning Circulation.
  2. ventilating the deep global oceans.
  3. sequestering carbon and nutrients in the deep global ocean.

The primary objectives of ANDREX are

  • Quantitative assessment of routes of Circumpolar Deep Water (CDW) and Antarctic Bottom Water (AABW) exchange between the Weddell Gyre and the rest of the Southern Ocean.
  • Estimation of rates of ventilation and AABW formation in the Weddell Gyre.
  • Quantification of heat and fresh water budgets of the Weddell Gyre, and determination of the fresh water inputs to the gyre (sea ice melt, precipitation, and glacial ice).
  • Quantification of the nutrient and carbon cycles of the Weddell Gyre.
  • Determination of the rate of sequestration of anthropogenic carbon into the deep Weddell Gyre.
  • Investigation of interannual to decadal variability of ventilation in, and AABW export from, the Weddell Gyre.

The fieldwork (see schematic above) comprised the collection of hydrographic, ventilation tracer and biogeochemical measurements along the outer rim of the Weddell Gyre (pink). Data were collected by a US Climate Variability (CLIVAR) section cruise repeating the World Ocean Circulation Experiment (WOCE) IR6S section (green), between South Africa and Antarctica along 30oE during January - February 2008; and the ANDREX section (red) along the gyre's northern edge between 30oE and the tip of the Antarctic Peninsula, during December - February 2009. The ANDREX section was started by the UK’s RRS James Cook cruise JC030 but was aborted approximately half-way due to a medical evacuation. It was completed in March - April 2010 on board the RRS James Clark Ross cruise JR239.

The programme is funded by the Antarctic Funding Initiative (AFI), with a contribution from the European Commission's CARBOOCEAN project, and brings together scientists from UK, German and US research institutions. ANDREX is coordinated by the National Oceanography Centre in Southampton.

Antartic Deep Water Rates of Export (ANDREX)