Southern Ocean
SOCCOM
Section titled “SOCCOM”The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project aims to understand the role of the Southern Ocean in the global carbon cycle and climate system.
Global air-sea CO2 flux estimates leveraging both ship and corrected BGC Argo observations
Section titled “Global air-sea CO2 flux estimates leveraging both ship and corrected BGC Argo observations”The Global Ocean Carbon uptake shows significant variability and uncertainty, as depicted by last Global Carbon Project (GCB) studies. Most of the pCO2 data used by mapping algorithms in GCB come from ship-based observations, which are sparse in both space and time, generally north hemisphere and summer dependent.
Fortunately, as part of the SOCCOM project, BGCArgo floats are deployed to collect biogeochemical data in the Southern Ocean, where ship-based observations are limited, increasing the spatial and temporal coverage of pCO2 measurements. These newly added BGCArgo data are adjusted and combined with SOCAT observations to help constrained global air-sea CO2 flux estimates, finally improving estimates of global ocean carbon uptake.
The first estimates of air-sea CO2 fluxes from these observations were published in Gray et al. (2018). We have combined these float estimates with the traditional ship-based measurements to produce new estimates of the Southern Ocean CO2 flux. This work, published in Bushinsky et al. (2019) affirmed the importance of the wintertime outgassing highlighted in the Gray et al. study.
We also investigated whether the difference between prior flux estimates and those that included float observations could be explained by the difference in where and when the floats sample relative to the shipboard data. We did this through a model subsampling approach, finding that much of the difference between CO2 flux estimates with and without float data can be explained by the increased coverage that floats provide. Additionally, we found that this change in the contemporary Southern Ocean CO2 flux had to be balanced by land or ocean fluxes in the Southern Hemisphere and that float observations every ten days were sufficient to resolve the annual CO2 flux at a given location.