The SOCCOM Project was launched in 2014 with a mission to drive a transformative shift in the scientific and public understanding of the role of the vast Southern Ocean in climate change and biogeochemistry through a combination of innovative, float-based observations and high-resolution modeling. Now entering Year 5 of the project, SOCCOM researchers have:

  • reached a milestone of over 100 biogeochemical floats operating in all 3 basins of the Southern Ocean;
  • developed a high-resolution biogeochemical Southern Ocean State Estimate (B-SOSE) that is now assimilating float data;
  • calculated float-based climatological seasonal cycles of carbon system variables and air/sea carbon fluxes across several zones of the Southern Ocean;
  • led a Southern Ocean Model Intercomparison Project (SOMIP), simulations from which have already produced significant and unexpected results;
  • published manuscripts on SOCCOM technology and early results, including 18 papers in a SOCCOM special issue of JGR-Oceans; and
  • successfully transferred SOCCOM float and sensor technology to the commercial float industry.

In addition, a substantial education and outreach effort has contributed to the training and education of 14 postdocs, 12 graduate students, and 33 undergraduate students at five different institutions and engaged thousands of members of the public through online events, social media, and a school-based adopt-a-float program.

Year 4 Progress


As of June 2018, 111 biogeochemical floats are operating in in the southern Atlantic, Pacific, and Indian basins of the Southern Ocean. The project is more than halfway toward its goal of ~200 floats deployed in the Southern Ocean (see Figure 1). SOCCOM floats have collected a total of over 3.5 million measurements nearly 8000 profiles, totaling ~200 float years of biogeochemical measurements made publicly available in real time via the SOCCOM website and the Argo data system.

SOCCOM adjusted biogeochemical data are providing an unparalleled view of Southern Ocean biogeochemistry. Results from Year 4  include:

  • Detection of a large, previously undocumented winter-time CO2 flux from the ocean to the atmosphere that has implications for global carbon cycling.
  • Calculation of the first basin-scale oxygen fluxes calculated directly from in situ observations, which indicate that the Southern Ocean oxygen sink is approximately twice as large as previously estimated.
  • Demonstration that accounting for Si-induced ballasting is key for the estimation of carbon export in the Southern Ocean. 

Biogeochemical Southern Ocean State Estimate (B-SOSE)

A major goal of the project is to expand the Southern Ocean State Estimate (SOSE) observation-model synthesis to produce an unprecedented 3-dimensional space and time resolved estimate of Southern Ocean biogeochemistry (B-SOSE). Optimization of B-SOSE for the years 2008 to 2012 with ⅓ degree resolution has been completed and the solution posted to for general use, along with extensive validation of the solution. Researchers are now working to produce a 2013 to 2017 B-SOSE, which includes assimilation of SOCCOM float data.

SOSE manuscripts in revision or published (12) during this reporting year include results on adjoint method assimilation of biogeochemistry, the Southern Ocean carbon and heat budgets, and dynamical formation of deep chlorophyll maxima. We have also been investigating Argo float trajectory behavior informed from SOSE statistics. Two papers have investigated added information from additional mapping methods.

SOCCOM physical process science (floats and SOSE)

In addition to its biogeochemical program, SOCCOM also improves understanding of the physics underlying climate in the Southern Ocean. SOCCOM researchers are currently using SOCCOM floats to study this past year’s very unusual Weddell polynya. Key published findings from Year 4 include determination of, process understanding of, and quantification of the pathways of northern deep waters, some carrying high carbon and cool waters, to the Southern Ocean sea surface (Tamsitt et al., 2017; Nature Comm.).


The modeling aspects of SOCCOM made progress on the following fronts: OSSE’s have been used to quantify “Reconstruction Skill” - a metric quantifying the uncertainty associated with observing systems (Kamenkovich et al., 2017); simulations were successfully used to envelope future float locations (Wang et al., 2018, JAOT); float data and model simulations were combined to determine the seasonal drivers of the carbon system (Williams et al. 2018, JGR-O); float data were used to establish a new algorithm for oxygen concentration based on temperature and salinity (Giglio et al., 2018, JGR-O); and Lagrangian tracers were used to examine the effects of resolution on mixing timescales (Drake et al., 2018, GRL).

A reassessment of “observed” oceanic uptake of anthropogenic carbon (from Sabine at al. 2004 and Khatiwala et al. 2009) has explained the previously cited differences between the two methods and found that they, and the CMIP5 ensemble estimates of total uptake, agree to within 4%, well within their margins of error (Bronselaer et al., 2017, GRL ).

Analysis of high resolution earth system models in Year 4 has shown that: heat and carbon uptake by the Southern Ocean are sensitive to the width of the simulated Southern Hemisphere westerly band (Russell et al., 2018, JGR-O); freshening along the shelf leads to a reduction of heat loss to the atmosphere and an increase in the subsurface heat content (Goddard et al., 2017, JGR-O; Bronselaer et al., submitted, Nature); the transformations of upwelling water masses in the Southern Ocean were highlighted by Lagrangian particle simulations (Tamsitt et al. 2018, JGR-O); uptake of anthropogenic carbon is sensitive to both resolution and eddy-parameterizations (Frenger et al. in prep.); mesoscale features are tied to the formation of the Weddell Sea polynya (Dufour et al., 2017, J. Climate); ; and primary production and export efficiency are inversely correlated in the Southern Ocean (Arteaga et al., 2018, JGR-O).

Broader Impacts

Knowledge Transfer

MBARI and UW have a long history of transferring float control and sensor technology to industry. Collaboration with two partner companies, SeaBird Electronics and Teledyne Webb Research, has resulted in first-generation commercial SOCCOM-type floats that are now available for use by the research community. pH sensors used in the SOCCOM program are now available as a commercial option from a variety of profiling float manufacturers.


Climate Central and MBARI currently lead the SOCCOM outreach program. This year the Adopt-a-Float program was expanded and has now reached students in 22 schools. The Climate Central team also completed 6 educational videos on Southern Ocean science, called “Deep Dives,” that are available online.  In addition, SOCCOM researchers were featured in a NOVA documentary, “Decoding the Weather Machine,” which used substantial amounts of film footage from a SOCCOM cruise on the R/V Palmer in 2016 that included a Climate Central Outreach team.


map image with dots for float locations