Although the results of this exercise do not solve this problem, they underline the importance of this aspect which must be taken into account in the construction of a consistent global f CO 2 database. In addition to this more general outcome, some of the results in more concrete terms follow. These may also serve as recommendations for future f CO 2 work in the ocean. In contrast, the equilibrator type and its flow rates of seawater and air are important aspects with respect to the time constant of the equilibration process. The importance of rather accurate measurements of in situ and equilibrator temperature does not seem to be addressed adequately in the community.
Calibration gases are an important issue.
Even with the provided suite of consistent calibration gases, the NDIR analyzers could only be calibrated to an accuracy of 0.5 to 1.0 ppmv. We feel that this is about the tolerable limit. So any further error contribution from the calibrated standard concentrations worsens the situation. Use of calibration gases that are traceable to the same primary standards, such as the WMO primary standards maintained at SIO, would be desirable.