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 4 of the project, SOCCOM researchers have deployed a growing observing network with biogeochemical floats 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; developed and published a technique for estimating ocean pCO2 from float pH measurements; initiated a Southern Ocean Model Intercomparison Project (SOMIP) with major climate modeling centers; published manuscripts on SOCCOM technology and early results, including 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 10 postdocs, 10 graduate students, and 20 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 3 Progress Observations As of June 2017, 80 biogeochemical floats are operating in in the southern Atlantic, Pacific, and Indian basins of the Southern Ocean. With 6 more floats to be deployed by the end of this season, the project is now approaching the halfway point toward its goal of ~200 floats deployed in the Southern Ocean. SOCCOM floats have collected a total of over 100 float years of pH, nitrate, oxygen, chlorophyll and backscatter measurements in over 4000 vertical profiles 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 3 include: Detection of a large, previously undocumented winter-time CO2 flux from the ocean to the atmosphere that has implications for global carbon cycling (Gray et al., to be submitted to Nature) Demonstration of no significant bias in NASA’s ocean color algorithms for chlorophyll and POC for the Southern Ocean in contrast to earlier studies based on limited data sets (Haentjens et al., J. Geophys. Res., 2017). Development of methods to determine Annual Net Community Production across the Southern Ocean with yearly resolution using profiling float sensors; estimates are consistent with previous observations (Johnson et al., J. Geophys. Res., 2017a) Assessment of biogeochemical sensor performance on SOCCOM profiling floats and demonstration of comparability of data with shipboard observations (Johnson et al., J. Geophys. Res., 2017b) 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). This year optimization of B-SOSE for the years 2008 to 2012 with ⅓ degree resolution was completed and the solution was posted to sose.ucsd.edu for general use, along with extensive validation of the solution. Researchers are now working to produce a 2013 to 2016 B-SOSE, which includes assimilation of SOCCOM float data. In addition, a 1/12° resolution model with 104 vertical levels is being tuned. SOSE manuscripts in revision (4) or published (6) 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. 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 3 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., Nature Comm., in press). A finding that the Southern Ocean overturning circulation is strongly influenced by the location and magnitude of sea ice formation and melt (Abernathey et al., Nature Geosciences, 2016). Modeling 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., accepted, in revision at JGR); the method for calculating the quantification of the air/sea carbon flux from standard biogeochemical floats has been published (Williams et al. 2017, GBC); the initial simulations for the Southern Ocean Model Intercomparison Program are underway, the protocol has been finalized (Russell et al. in prep.) and analysis packages will be made public at the ESMValTool conference in August. Application of an aragonite saturation algorithm to ESM simulations has indicated that month-long subsurface aragonite undersaturation is projected to begin as early as 2022 and surface undersaturation as early as 2040 and year-long surface undersaturation will commence by 2062 (Williams et al., submitted JGR). 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., submitted GRL). Analysis of high resolution earth system models in Year 3 has shown that: heat and carbon uptake by the Southern Ocean is sensitive to the width of the simulated Southern Hemisphere westerly band (Russell et al., in revision for JGR); upwelling in the Southern Ocean is closely tied to topographic features (Tamsitt et al. 2016); 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., submitted, J. Climate); CO2 uptake leads to warming around the edge of the Antarctic ice sheet (Goddard et al., submitted, JGR); and primary production and export efficiency are inversely correlated in the Southern Ocean (Arteaga et al., in prep. JGR). 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 commercial option from a variety of profiling float manufacturers. Outreach Climate Central leads the SOCCOM outreach program. In addition to producing multimedia content and learning materials, Climate Central also piloted and is now formalizing an adopt-a-float program with school classrooms around the country. In addition, two members of the SOCCOM team from Climate Central participated in a month-long cruise deploying SOCCOM floats on a track from Punta Arenas, Chile to McMurdo Station in Antarctica. Greta Shum and Ted Blanco documented the experience through blogs and social media and also collected hundreds of photos and hours of video footage and scientist interviews that the team will use to develop a free-standing website on the Southern Ocean targeting the general public (see “Impacts” section of report for details).
