In 2014, the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project was launched with a vision to enable a transformative shift in scientific and public understanding of the role of the Southern Ocean in climate change and biogeochemistry. This past year was the second year of active spending of the SOCCOM2 award, a 4-year grant that continues the original SOCCOM project to obtain a decade of Southern Ocean observations.

In the past 8 years, SOCCOM researchers have:

  • Deployed over 226 biogeochemical floats, with 113 currently operating in all 3 basins of the Southern Ocean;
  • Developed a high-resolution biogeochemical Southern Ocean State Estimate (B-SOSE) that is assimilating float data;
  • Calculated float-based climatological seasonal cycles of oxygen, nitrate, and carbon system variables and air/sea carbon fluxes across the Southern Ocean, including seasonal ice zones;
  • Carried out model simulations that suggest a new climate feedback mechanism from Antarctic meltwater
  • Led a Southern Ocean Model Intercomparison Project (SOMIP), simulations from which have already produced significant and unexpected results;
  • Published over 160 manuscripts on SOCCOM technology and early results, including in 2 AGU special collections
  • Successfully transferred SOCCOM float and sensor technology to the commercial float industry.

In addition, a substantial education effort has contributed to the training and education of 19 postdocs, 22 graduate students, and 50 undergraduate students at the partner institutions. 59% of these junior researchers have been female and nearly 9% have been participants from under-represented groups, with highest participation of under-represented groups at the undergraduate level. More broadly, SOCCOM’s outreach efforts have engaged thousands of members of the public through online events and via social media with compelling stories highlighting SOCCOM research. With 153 floats adopted so far, the popular Adopt-a-Float program partners teachers and classrooms around the world with SOCCOM researchers by providing students the chance to name and track their very own float and educating them about Southern Ocean biogeochemistry and climate change.

2021 -2022 Progress


Physical and biogeochemical observations

We developed the numerical tools to extract the diel cycle of oxygen produced by primary productivity from the BGC-Argo data set (Johnson and Bif, 2021). This allowed a direct calculation of global ocean primary productivity for the first time. Prior estimates were derived from satellite observations of ocean color and model of photobiology, or by extrapolating sparse measurements from ships to the global realm.

Two seminal papers that describe the role of sub-surface processes on the spatial variability of air-sea CO2 exchange in the Southern Ocean were submitted to Global Biogeochemical Cycles (Prend et al., 2022; Chen, Haumann, et al., 2022).  Both papers find that the outgassing flux in the Antarctic Southern Zone is dominated by fluxes from the Indo-Pacific region, while fluxes in the Atlantic region are much smaller. Prend et al., which examines the role of spatial variability in obduction, has been published.  Chen, Haumann, et al., examines the role of subsurface respiration and calcium carbonate dissolution in regulating the pCO2 of upwelled water.

In a joint observation and modeling study, Prend et al. (2022) assessed the processes that regulate the seasonal cycle of pCO2, which changes annual phase from north to south. Johnson et al. (submitted), merged observations and B-SOSE to examine spatial variations in the carbon to nitrate assimilation ratio of phytoplankton.  As also described below in ‘Modeling’, Shi et al. (Nature Climate Change,  2021) examined Argo, hydrography, satellite altimetry, with comparisons with CMIP6 and CESM1 large ensemble models, and showed an acceleration of the northernmost front of the Antarctic Circumpolar  Current since the early 1990s, driven  by increased heating north of the ACC.

Float technology and data management. 

Maurer et al. (2021) describe the software and processes used to quality control SOCCOM profiling float data.  All of the quality control software is in the public domain and available on the SOCCOM github repository (https://github.com/SOCCOM-BGCArgo). 

SOCCOM data continues to be released in real-time through the Argo data system, as well as from servers accessible through the SOCCOM website. Complete snapshots of the entire SOCCOM dataset with a Digital Object Identifier were released in September 2021 (doi.org/10.6075/J0CF9Q81), December 2021 (doi.org/10.6075/J00R9PJW), and May 2022 (doi.org/10.6075/J0MC905G) to facilitate access to reproducible datasets for researchers. A new algorithm for temperature compensation of the ISUS nitrate sensor was developed and applied to the entire data set before the May 2022 snapshot was created. Technical data on the algorithm has been made available to the Argo community and a publication is in preparation.

Development of an improved pH sensor that is designed to increase reliability has been completed. Three floats with the improved sensor have been deployed and all are operating normally.  Future sensor construction will utilize this new design in most cases, while supplies of the earlier design are slowly used up.

Firmware was developed to operate Sea-Bird OCR radiometers on Apex floats.  Two floats carrying only radiometers were constructed and deployed to test the firmware and they operated as expected.  SOCCOM Apex floats with radiometers are now in construction.


  1. Constraint on net primary productivity of the global ocean by Argo oxygen measurements. Johnson, K.S. and M.B. Bif (2021).  Nature Geoscience. DOI:10.1038/s41561-021-00807-z
  2. Indo-Pacific sector dominates Southern Ocean carbon outgassing. Prend, C. J., Gray, A. R., Talley, L. D., Gille, S. T., Haumann, F. A., Johnson, K. S., et al. (2022). Global Biogeochemical Cycles, 36, e2021GB007226. https://doi.org/10.1029/2021GB007226
  3. Chen, H., F.A. Haumann, L.D. Talley, K.S. Johnson, J. Sarmiento, 2022. The deep ocean's carbon exhaust. Global Biogeochemical Cycles, accepted.
  4. Controls on the boundary between thermally and non-thermally driven pCO2 regimes in the South Pacific. Prend, C.J., J.M. Hunt, M.R. Mazloff, S.T. Gille, and L.D. Talley (2022). Geophys. Res. Lett., DOI: 10.1029/2021GL095797
  5. Carbon to nitrogen uptake ratios observed across the Southern Ocean by the SOCCOM profiling float array. Johnson, K.S., M.R. Mazloff, M.B. Bif, Y. Takeshita, H.W. Jannasch, T.L. Maurer, J.N. Plant, A. Verdy, P.M. Walz, S. Riser, and L.D. Talley. Submitted to JGR-Oceans.
  6. Ocean warming and accelerating Southern Ocean zonal flow. Shi, JR., Talley, L.D., Xie, SP. Peng, Q., Liu, W.  (2021). Nat. Clim. Chang. DOI:10.1038/s41558-021-01212-5
  7. Delayed-Mode Quality Control of Oxygen, Nitrate, and pH Data on SOCCOM Biogeochemical Profiling Floats. Maurer T.L., J.N. Plant and K.S. Johnson (2021). Front. Mar. Sci. 8:683207. doi: 10.3389/fmars.2021.683207

Southern Ocean State Estimate 

The BSOSE group participated in eight total publications this year. This included work using BSOSE to help explain the migratory behavior of grey petrels in the Southern Ocean (Jones et al 2021). The results highlight the need to consider advective connections between regions and to re-evaluate the ecological relevance of oligotrophic regions from a conservation perspective. 

The BSOSE setup in 1/3, 1/6, and 1/12 configurations was analyzed in  work by University of Arizona graduate student Stan Swierczek (Swierczek et al 2021a and 2021b). Stan focused on the Argentine Basin. In the first paper the models are validated, and differences in the heat and carbon budgets are compared in the non-eddying 1/3 run and the mesoscale eddying 1/12 run. The budgets are quite different, and the carbon fluxes in particular. This suggests earth system models of the carbon system will be very sensitive to model resolution. In the second paper we looked at deterministic predictability of carbon and SST in the model runs. The 1/12 model is predictable for about 2 weeks. This suggests 10-day Argo sampling is sufficient to constrain the mesoscale state in time. The 1/3 is predictable for much longer, but the solution doesn’t remain true to the 1/12 response for longer than ~8 days suggesting a loss of realism in the coarse model. 

In Castro et al. (2022) we analyzed the contributions of subtropical waters and subpolar waters to Sub-Antarctic Mode Waters (SAMW) using BGC-Argo and observationally derived products.  SAMW are subducted into the ocean interior, and the partitioning strongly impacts what is being subducted given the strong property differences between these source waters. A follow-on work is in progress repeating this effort using BSOSE to add insight into the processes at play in the partitioning. 

In Prend et al. (2022) BGC-Argo float data are analyzed to diagnose the leading driver of pCO2 seasonality shifts in latitude. We show that the boundary between pCO2 regimes is primarily set by the poleward decrease in sea surface temperature seasonal cycle amplitude, which is in term linked to mixed layer depth. We are currently using this information to diagnose biases in BSOSE. 

The BSOSE infrastructure was used in Trossman et al. (2022) to investigate the feasibility of using biogeochemical ocean measurements, here oxygen, to constrain levels of turbulence in the ocean.  Here data assimilation is used to show information flow between biogeochemical and physical model components, and results suggest, perhaps unsurprisingly, a strong link. Other work investigated other BGC modeling infrastructures. In Carroll et al. (2022) we analyze the upper ocean global carbon budget in NASA’s ECCO-Darwin data assimilating state estimate. 

Carroll et al. (2022) sheds light on the global carbon budget. We have also been looking at oxygen budget in remote locations to understand the mechanisms of oceanic ventilation in general. In particular, in Eddebbar et al (2021) we consider the tropical Pacific, which is characterized by large poorly-ventilated anoxic regions. What sets the size and variability of these regions is poorly quantified. In this paper we examine the effects of Tropical Instability Vortices (TIVs) on oxygen distributions and variability in the equatorial Pacific, and show that they oxygenate the upper ocean through a series of processes leading to a temporary deepening of the oxygen minimum zones. Thus TIVs are important to properly represent in ocean models, especially with respect to accurate representation of biogeochemical properties. Similar dynamics are likely at play in the Southern Ocean, with implications for explaining the signals observed by the floats. 

The latest BSOSE iteration (I136) was released, and covers the period 2013-2021 at 1⁄6 degree. The BSOSE user base continues to grow, and numerous publications using BSOSE from external research groups were identified this past year. We are also working to make BSOSE available via ERDDAP (https://equator.ucsd.edu/). This will give users the ability to crop exact regions and times of interest. Finally, the BSOSE group is working to make a pH, NO3, and O2 climatology. A pH climatology has been developed and will be published in the next reporting cycle.


  1. Attribution of space-time variability in global-ocean dissolved inorganic carbon. Carroll, D., D. Menemenlis, S. Dutkiewicz, J.M. Lauderdale, J.F. Adkins, K.W. Bowman et al. (2022). Global Biogeochemical Cycles, 36, e2021GB007162. DOI: 10.1029/2021GB007162
  2. Subtropical contribution to Sub-Antarctic Mode Waters. Castro, B. F., Mazloff, M., Williams, R. G., & Naveira Garabato, A. C. (2022). Geophysical Research Letters, 49, e2021GL097560. DOI: 10.1029/2021GL097560
  3. Tracer and observationally derived constraints on diapycnal diffusivities in an ocean state estimate. Trossman, D. S., Whalen, C. B., Haine, T. W. N., Waterhouse, A. F., Nguyen, A. T., Bigdeli, A., Mazloff, M., and Heimbach, P. (2022). Ocean Sci., 18, 729–759.  DOI: 10.5194/os-18-729-2022
  4. Controls on the boundary between thermally and non-thermally driven pCO2 regimes in the South Pacific. Prend, C.J., J.M. Hunt, M.R. Mazloff, S.T. Gille, and L.D. Talley (2022). Geophys. Res. Lett., DOI: 10.1029/2021GL095797
  5. Seasonal Modulation of Dissolved Oxygen in the Equatorial Pacific by Tropical Instability Vortices. Eddebbar, Y. A., Subramanian, A. C., Whitt, D. B., Long, M. C., Verdy, A., Mazloff, M. R., & Merrifield, M. A. (2021). Journal of Geophysical Research: Oceans, 126, e2021JC017567. DOI:10.1029/2021JC017567
  6. Untangling local and remote influences in two major petrel habitats in the oligotrophic Southern Ocean. Jones, D. C., F.R. Ceia, E. Murphy, K. Delord, R.W. Furness, A. Verdy, M. Mazloff, R.A. Phillips, P.M. Sagar, J.-B. Sallée, B. Schreiber,D.R. Thompson, L.G. Torres, P.J. Underwood, H. Weimerskirch, and J.C. Xavier (2021). Global Change Biology, 27, 5773– 5785. DOI:10.1111/gcb.15839
  7. Investigating predictability of DIC and SST in the Argentine Basin through wind stress perturbation experiments. Swierczek, S., Mazloff, M. R., & Russell, J. L. (2021). Geophysical Research Letters, 48, e2021GL095504. DOI:10.1029/2021GL095504
  8. The effect of resolution on vertical heat and carbon transports in a regional ocean circulation model of the Argentine Basin. Swierczek, S., M.R. Mazloff, M. Morzfeld, M., and J.L. Russell (2021).  Journal of Geophysical Research: Oceans, 126, e2021JC017235. DOI:10.1029/2021JC017235


The SOCCOM Modeling group participated in eight (8) publications this year. Key outcomes include work related to: the Southern Ocean Model Intercomparison Project (SOMIP), metrics assessing climatically important ocean currents, water mass formation in the CMIP6 simulations, model resolution, and wind stress perturbations. These results reinforce the significance of and sensitivity to wind forcing in simulations on the ocean for both the current state and in the projected response to anthropogenic forcing.

In Beadling et al. 2022 (https://doi.org/10.1029/2021JC017608), part of our series of SOMIP experiments, important sensitivities and mechanisms were revealed between the differing responses of GFDL-ESM4 and GFDL-CM4 to the combined wind and freshwater perturbation forcing known as AntStress in FAFMIP. The results demonstrate the strong influence that the Antarctic Slope Current has on governing changes along the shelf, highlighting the importance of coupling interactive ice sheet models to ocean models that can resolve these dynamical processes.

In Shi et al. 2021 (https://doi.org/10.1038/s41558-021-01212-5), an observed acceleration along the northern flank of the ACC is documented from float data and reproduced in a hierarchy of climate models. The models indicate that ocean warming is causing the faster flow (the direct effects of the wind increase are secondary) and that continued warming may further accelerate the zonal flow.  

A pair of studies (MacGilchrist et al. 2021, doi:10.1029/2020GL092340; Almeida et al. 2021, DOI:10.1029/2021JC017173) describe mechanisms and sensitivities of sub-surface water mass production. MacGilchrist et al. (2021) uses a particle tracking method to document the changes in North Atlantic Deep Water production in which atmospheric forcing anomalies in the deepest winter are communicated and preserved below the mixed layer. They conclude that the signature of persistent strong atmospheric forcing driving deep mixed layers is preferentially ventilated to the interior when the forcing is ceased. Almeida et al. (2021), on the other hand, demonstrates in the CMIP6 simulations that the interactions between wind and buoyancy forcing that drives the formation of Subantarctic Mode Water and Antarctic Intermediate Water vary from year-to-year and model-to-model in complex ways. They conclude that correlations between AAIW and SAMW transports and air-sea fluxes (wind or buoyancy) are not stationary in time, limiting the predictive skill of statistical models and highlighting the importance of using complex climate models.


  1. Importance of the Antarctic Slope Current in the Southern Ocean response to ice sheet melt and wind stress change; Beadling, R.L., J.P. Krasting, S.M. Griffies, W.J. Hurlin, B. Bronselaer, J.L. Russell, et al. (2022).  Journal of Geophysical Research: Oceans, 127, e2021JC017608. DOI:10.1029/2021JC017608
  2. The Role of Continental Topography in the Present-Day Ocean’s Mean Climate; Stouffer, R.J., J.L. Russell, R.L. Beadling, A.J. Broccoli, J.P. Krasting, S. Malyshev and Z. Naiman (2022). Journal of Climate, 35, 1327-1346. DOI: 10.1175/jcli-d-20-0690.1
  3. Ocean warming and accelerating Southern Ocean zonal flow; Shi, JR., Talley, L.D., Xie, SP. Peng, Q., Liu, W.  (2021). Nature Climate Change, DOI:10.1038/s41558-021-01212-5
  4. Southern Ocean [in "State of the Climate in 2020"]; Tamsitt, V., S. Bushinsky, Z. Li, M. du Plessis, A. Foppert, S. Gille, S. Rintoul, E. Shadwick, A. Silvano, A. Sutton, S. Swart, B. Tilbrook, and N.L. Williams, 2021. Bull. Amer. Meteor. Soc., 102 (8), S341-S345, DOI:10.1175/BAMS-D-21-0081.1
  5. Investigating predictability of DIC and SST in the Argentine Basin through wind stress perturbation experiments; Swierczek, S., Mazloff, M.R., & Russell, J.L. (2021). Geophysical Research Letters, 48, e2021GL095504. DOI:10.1029/2021GL095504
  6. Demons in the North Atlantic: Variability of deep ocean ventilation; MacGilchrist, G.A., Johnson, H.L., Lique, C., & Marshall, D.P. (2021). Geophysical Research Letters, 48, e2020GL092340. DOI:10.1029/2020GL092340
  7. The impact of Southern Ocean Ekman pumping, heat, and freshwater flux variability on intermediate and mode water export in CMIP models: Present and future scenarios; Almeida, L., M.R. Mazloff and M.M. Mata (2021). Journal of Geophysical Research: Oceans, 126, e2021JC017173. DOI:10.1029/2021JC017173
  8. The effect of resolution on vertical heat and carbon transports in a regional ocean circulation model of the Argentine Basin; Swierczek, S., M.R. Mazloff, M. Morzfeld and J.L. Russell (2021). Journal of Geophysical Research: Oceans, 126, e2021JC017235. DOI:10.1029/2021JC017235

Broader Impacts

Highlights from the year’s Broader Impacts activities include:

  • Adopt-a-Float program (since June 2021)
    • 22 floats adopted
    • 2 blogs posted
    • 4 virtual Adopt-a-Float presentations given
    • Floats adopted in 36 states and 5 countries  
  • Social Media (as of June 1, 2022)
  • Multimedia resources
    • Animations: 
    • Explainer video for Adopt-a-Float audience about how the ocean, like land, has a seasonal cycle
    • 2 Scientist Selfies featuring SOCCOM/GO-BGC scientists Ben Davis and Tanya Maurer, produced for National Ocean month (in coordination with NSF)
  • Science communication training
map image with dots for float locations