Checks and Calculation Routines

The main idea of the exercise was to compare the surface seawater fCO₂ data as measured by all participating instruments under identical conditions. This was to some extent accomplished by providing the infrastructure during the exercise, such as a common seawater and calibration gas supply. The same care, however, that had been taken on the side of the logistical infrastructure was also advisable with respect to ancillary measurements as well as the calculation procedures involved in the computation of final fCO₂ values. This issue was addressed in different ways. In the following sections we describe the results of two different experiments: (1) a check of the performance of the calibration procedures for CO₂, and (2) a check of all temperature sensors that were used to measure the seawater temperature in the equilibrators. We also describe the common procedure of the calculation of final fCO₂ values and of the synchronization of the final fCO₂ profiles.