Dissolved inorganic carbon, pH, temperature, salinity and other variables collected from time series and surface observations using Moored Autonomous Dissolved Inorganic Carbon (MADIC) System, Sunburst SAMI2 pH sensor, and other instruments from Kewalo Buoy near the coast of Honolulu, Hawaii from 2013-10-31 to 2014-06-15 (NCEI Accession 0132048)

To expand the number of tools available for autonomous carbonate system observations, we have developed a robust surface ocean dissolved inorganic carbon (DIC) sensor capable of extended (>year) field deployments with a laboratory determined uncertainty of plus/minus 5 umol kg-1. The prototype sensor was deployed off shore of Honolulu, Hawaii for seven months on a moored buoy equipped with a Sea-Bird Electronics CTD and SAMI pH sensor unit. The buoy was deployed ~25m from an existing CO2 buoy, which allowed us to over constrain the carbonate system and thoroughly evaluate the performance of the prototype DIC sensor. In addition, 51 discrete bottle samples were collected throughout the seven month deployment and analyzed for DIC via coulometry. Results from this field test confirm that direct measurement of DIC is ~90% more accurate than estimates of DIC calculated from contemporaneous and collocated measurements of pH and CO2. The improved accuracy from directly measuring DIC gives rise to new opportunities for quantitative, autonomous carbon cycle studies.