SOS-Carbon: Southern Ocean Storminess and the Carbon Cycle
Nicole Lovenduski, University of Colorado Boulder (Principal Investigator)
Cara Nissen, University of Colorado Boulder (Co-Investigator)
Mathew Maltrud, Los Alamos National Laboratory (Co-Investigator)

The Southern Ocean is home to the deepest mid-latitude cyclones in the world and plays a dominant role in the global carbon cycle by delivering carbon-rich water to the surface ocean.  A recent observational study using gliders in the Southern Ocean found that the passage of mid-latitude cyclones generated episodes of mixed layer carbon entrainment and produced extreme rates of carbon dioxide (CO₂) outgassing.  Extreme Southern Ocean mid-latitude cyclones are projected to increase in frequency over the coming century due to anthropogenic climate change, setting up a potentially large, but previously unexplored, carbon-climate feedback.  Despite their potentially important role in the coupled carbon-climate system, and their capacity to engender a carbon-climate feedback over the coming century, the role of storms in the Southern Ocean carbon cycle is not well-understood. 

The project team aims to test the hypothesis that mid-latitude cyclones play an outsized role in the Southern Ocean carbon cycle and drive a carbon-climate feedback.  Output from a novel high-resolution Southern Ocean configuration of a global ocean physical and biogeochemical model with the capacity to simulate autonomous Biogeochemical-Argo floats will be combined with real-world float observations to (1) quantify and diagnose the role of mid-latitude cyclones ('storminess') in the Southern Ocean carbon cycle, (2) estimate the ability of Biogeochemical-Argo floats to sample the carbon cycle response to Southern Ocean cyclones, and (3) quantify the carbon-climate feedback associated with Southern Ocean storms.

The team will use statistical analysis techniques and storm tracking algorithms to quantify the impact of individual storms on key variables in the carbon cycle, to quantify the basin- and time-integrated influence of Southern Ocean storms on air-sea CO₂ flux, and to diagnose the drivers of these storm-related anomalies.  They will evaluate the carbon cycle response to Southern Ocean cyclones in the current observational network, and estimate the magnitude of the Southern Ocean storm carbon-climate feedback.

This project will enhance understanding of carbon-climate feedbacks in a rapidly changing, high latitude region critical to the atmospheric CO₂ concentration, and help improve regional and global model projections.  The team will examine interactions across a range of temporal scales (sub-daily to centennial) and spatial scales (mesoscale to basin-scale) that will facilitate understanding, quantification, and reduction of Southern Ocean carbon-climate feedback uncertainty.