Southern Ocean Biogeochemical Float Deployment Strategy, With Example From the Greenwich Meridian Line (GO-SHIP A12).

Area of Science:

• Oceanography
• Climate Science
• Biogeochemistry

Background:

• The Southern Ocean is critical for global carbon and climate regulation.
• Biogeochemical Argo floats provide essential data on ocean properties.
• Previous oceanographic coverage in the Southern Ocean was sparse.

Purpose of the Study:

• To establish the first comprehensive annual cycles of carbon, oxygen, nitrate, and optical properties in the Southern Ocean.
• To evaluate the deployment strategy for the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) program.
• To assess the predictive accuracy of float pathways.

Main Methods:

• Deployment of 200 biogeochemical Argo floats profiling to 2,000m depth.
• Utilizing prior knowledge of water mass properties, circulation, and ocean models (HYCOM) for deployment strategy.
• Analyzing data from 12 test floats deployed during the 2014-2015 Polarstern cruise.

Main Results:

• Floats successfully represent targeted deployment zones, including the Weddell Gyre, Antarctic Circumpolar Current (ACC), and Cape Basin.
• The Southern Zone 'chimney' in the ACC shows significant carbon dioxide outgassing due to upwelling.
• Argo float trajectories and HYCOM simulations accurately predicted float pathways.

Conclusions:

• The SOCCOM float deployment strategy is effective in covering key Southern Ocean regions.
• Biogeochemical Argo floats are crucial for understanding Southern Ocean carbon cycling and climate interactions.
• Predictive models like HYCOM are valuable tools for planning and interpreting float deployments.