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. The SOCCOM research program consists of an observational effort to deploy ~200 autonomous biogeochemical profiling floats in the Southern Ocean in order to substantially increase the number of observations from the region, complemented by a high-resolution Southern Ocean state estimate (SOSE) and a high-resolution Earth-system modeling program. Observations At the end of SOCCOM’s first year, 23 autonomous floats had been deployed in the Pacific and Atlantic basins, substantially increasing the number of biogeochemical measurements in the Southern Ocean. Now ending Year 2, the SOCCOM observations team has more than doubled the size of this network, expanding the system to 52 autonomous floats with biogeochemical sensors operating in the southern Atlantic, Pacific, and Indian ocean basins. The twenty-nine new floats were deployed in partnership with the GOSHIP and Ocean Observatories Initiative (OOI) programs and research teams from Germany, the UK and Australia. The SOCCOM project is now ¼ of the way to its goal of ~200 floats deployed and operating in the Southern Ocean. SOCCOM adjusted biogeochemical data are providing an unparalleled view of Southern Ocean biogeochemistry, yielding information on variability of pH and carbonate saturation in the system, net community production, carbon export, and air-sea fluxes of biogeochemical parameters and bloom dynamics. Specifically, SOCCOM floats have: Collected over 20 float years of pH, nitrate, oxygen, chlorophyll and backscatter measurements in over 1800 vertical profiles; Increased the number of pH profiles taken south of 40S in austral winter by 117 times Made the first measurements of the annual cycle of pH in open waters of the Southern Ocean, with annual cycles measured in the Pacific, Atlantic, and Indian sectors. Made the first measurements of the annual cycle of pH, oxygen and nitrate in ice-covered waters of the open Southern Ocean In addition, the SOCCOM observations team has developed improved procedures for quality control and adjustment of autonomous sensor data and validated a method for calibrating post-deployment float oxygen measurements by using air oxygen values. Raw and adjusted biogeochemical data for all floats are made publicly available in real time at SOCCOMViz, a data portal developed and hosted by MBARI and embedded in the SOCCOM website. Users can either use the interface to view and create plots of the SOCCOM data or download tab-delimited, ASCII text files in OceanDataView format. FTP access to the data, including the relatively large high-resolution data files (CTD at 2 m resolution, with biogeochemical data at lower resolution) is also available. In addition, in Year 2 a user-friendly interactive map was developed that shows float locations and trajectories and provides links to raw and QC’d data for each float. Links to shipboard data and reports from SOCCOM cruises are also available through our “Shipboard Data and Reports” page, and data are currently being manually uploaded to the Argo data system, with full automation projected by Fall 2016. Southern Ocean State Estimate (SOSE) The biogeochemical data-model synthesis machinery for the Southern Ocean State Estimate is working: the model-data misfit is being reduced via the adjoint method. The optimization for the years 2008 to 2010 will be completed soon and the solution will be posted to http://sose.ucsd.edu for general use. Validation of the solution will also be presented in the form of a comparison to data and to other derived products. Analysis of the integrated biogeochemical data set will be greatly enriched by the data assimilating Biogeochemical Southern Ocean State Estimate. A 1/12° resolution model with 104 vertical levels, which is being tuned using information gained from the data assimilation, will also aid analysis efforts. Extensive validation documentation has been produced and evaluation of the current solutions is at http://sose.ucsd.edu/bsose_valid.html. Optimized solutions will soon be made available at sose.ucsd.edu. Modeling The modeling aspects of SOCCOM made progress on the following fronts: OSSE’s have been used to quantify decorrelation length scales in order to estimate the number of global SOCCOM- type biogeochemical floats necessary to reduce the uncertainty in the estimate of the oceanic uptake of anthropogenic carbon by half (need ~1000 globally). This information was presented at the recent G7 meeting in Japan and the council of experts recommended that the science ministers support the development and implementation of a global array. The publication of the pH algorithm for the Southern Ocean (Williams et al. 2016) and an alkalinity algorithm (Carter et al. 2016) enables the quantification of the carbon system from standard biogeochemical floats and as a proxy in coupled climate models with simplified or no biogeochemical modules. The initial plans for the Southern Ocean Model Intercomparison Program are complete and preliminary “proof of concept” simulations and analysis packages should be carried out shortly so that they can be formally submitted to WCRP/CMIP6.