The goal of the SOCCOM float program is to produce a climate-quality data record for carbon cycling. That is a "time series of measurements of sufficient length, consistency and continuity to determine climate variability and change" (US NRC, Climate Data Records from Environmental Satellites, 2004). Such a record requires a sensor that is well characterized and calibrated to the property of interest before deployment, and whose calibration is assessed at deployment with high quality hydrographic measurements, or in which post-deployment calibration is possible. It must be possible to assess sensor stability and degradation with sufficient accuracy to allow the desired climate signal to remain detectable. This goal mandates that SOCCOM floats and their operation have four essential characteristics. These characteristics are as follows:
Sensor | Oxygen | Nitrate | pH | Chlorophyll |
Initial accuracy | 2 µmol/kg | 1 µmol/kg | 0.01 |
N.b. – these specs are not as stringent as GO-SHIP measurements, but probably what can be achieved.
SOCCOM Floats & Sensors
Environmental Issues and the Argo Array
Stephen C. Riser, University of Washington, Susan Wijffels, Woods Hole Oceanographic Institution
and the Argo Steering Team (2020).
Profiling Floats in SOCCOM: Technical Capabilities for Studying the Southern Ocean
Riser, S., D. Swift, and R. Drucker (2018). J. Geophys. Res. Oceans. doi 10.1002/2017/JCO13419
Biogeochemical sensor performance in the SOCCOM profiling float array
Johnson, K.S., J.N. Plant, L.J. Coletti, H.W. Jannasch, C.M. Sakamoto, S.C. Riser, D.D. Swift, N.L. Williams, E. Boss, N. Haëntjens, L.D. Talley, J.L. Sarmiento (2017). J. Geophys. Res. Oceans., 122, 6416–6436. doi: 10.1002/2017JC012838
Biogeochemical Sensors
pH
Processing BGC-Argo pH data at the DAC level
Johnson K.S., J.N. Plant, T.L. Maurer (2017). doi: 10.13155/57195
Deep-Sea DuraFET: A pressure tolerant pH sensor designed for global sensor networks
Johnson, K. S., H. W. Jannasch, L. J. Coletti, V. A. Elrod, T. R. Martz, Y. Takeshita, R. J. Carlson, J. G. Connery (2016). Analytical Chemistry, 88 (6), pp 3249–3256. doi: 10.1021/acs.analchem.5b04653
Testing the Honeywell Durafet® for seawater pH applications
Martz, T. R., J. G. Connery and K. S. Johnson (2010). Limnology and Oceanography: Methods, 8, 172-184. doi:10.4319/lom.2010.8.172
An evaluation of pH and NO3 sensor data from SOCCOM floats and their utilization to develop ocean inorganic carbon products
Wanninkhof, R., K. Johnson, N. Williams, J. Sarmiento, S. Riser, E. Briggs, S. Bushinsky, B. Carter, A. Dickson, R. Feely, A. Gray, L. Juranek, R. Key, L. Talley, J. Russel, and A. Verdy. SOCCOM Carbon System Working Group white paper.
Oxygen
Accurate oxygen measurements on modified Argo floats using in situ air calibrations
Bushinsky, S. M., S. R. Emerson, S. C. Riser, and D. D. Swift. (2016). Limnol. Oceanogr. Methods, doi:10.1002/lom3.10107.
Air Oxygen Calibration of Oxygen Optodes on a Profiling Float Array
Johnson, K. S., Plant, J. N., Riser, S. C., & Gilbert, D. (2015). Journal of Atmospheric and Oceanic Technology, 32(11), 2160–2172. doi:10.1175/JTECH-D-15-0101.1
Evaluation of a lifetime-based optode to measure oxygen in aquatic systems
Tengberg, A., J. Hovdenes, H.J. Andersson, O. Brocandel, R. Diaz, D. Hebert, T. Arnerich, C. Huber, A. Körtzinger, A. Khripounoff, F. Rey,C . Rönning, J. Schimanski, S. Sommer, A. Stangelmayer (2006). Limnology and Oceanography: Methods, 4, 2. doi:10.4319/lom.2006.4.7
Nitrate
Long-term nitrate measurements in the ocean using the In Situ Ultraviolet Spectrophotometer: sensor integration into the Apex profiling float
Johnson, K. S., L. J. Coletti, H. W. Jannasch, C. M. Sakamoto, D. Swift, S.C. Riser (2013). J. Atmos. Oceanic Technol., 30, 1854-1866. doi:10.1175/JTECH-D-12-00221.1
Bio-optics
Revisiting Ocean Color algorithms for chlorophyll a and particulate organic carbon in the Southern Ocean using biogeochemical floats
Haëntjens, N., E. Boss, and L.D. Talley (2017). J. Geophys. Res. Oceans. Accepted Author Manuscript. doi:10.1002/2017JC012844
Observations of pigment and particle distributions in the western North Atlantic from an autonomous float and ocean color satellite
Boss, E., D. Swift, L. Taylor, P. Brickley, R. Zaneveld, S. Riser, M.J. Perry, P.G. Strutton (2008). Limnology and Oceanography, 53, 5part2. doi:10.4319/lo.2008.53.5_part_2.2112
Primer regarding measurements of chlorophyll fluorescence and the backscattering coefficient with WETLabs FLBB on profiling floats
Boss, E., and N. Haëntjens, (2016). SOCCOM Tech. Rep. 2016-1.