With the advent of new sensors and platforms to measure surface water CO₂ levels, the dataset quality control criteria are updated in SOCAT to accommodate surface water fugacity of CO₂ (fCO₂) data from these sensors.

The report on the incorporation of alternative sensors in SOCAT is now available at SOCAT, CDIAC and IOCCP websites. SOCAT version 1.5 and 2.0 releases mostly contain data acquired from automated underway pCO₂ systems based on infrared analysis (IR) of CO₂ in the headspace of equilibrators operated on research and commercial vessels, largely following the standard operating procedures (SOP) as outlined in SOP 5 of Dickson et al. (2007). Some older data (prior to ~1995) were measured by gas chromatographic (GC) analysis of the CO₂ content in the headspace. During the assembly and quality control of an updated SOCAT release (version 2.0), observations were submitted from alternative platforms and alternative sensors whose data did not fit well in the current quality assessment scheme. It is anticipated that in the future there will be significantly more data arising from alternate approaches. This requires a reassessment of dataset quality control flags, as used for versions 1.5 and 2.0. In this report the authors provide recommendations regarding fCO₂ measurements made from platforms other than ships, and instruments that differ from conventional IR headspace analysis from flowing equilibrators.

Please cite this document as:

Wanninkhof, R., Bakker, D. C. E., Bates, N., Olsen, A., Steinhoff, T., and Sutton, A. J. (2013) Incorporation of Alternative Sensors in the SOCAT Database and Adjustments to Dataset Quality Control Flags. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, US Department of Energy, Oak Ridge, Tennessee. doi: 10.3334/CDIAC/OTG.SOCAT_ADQCF.