Intercalibration as a means of producing consistent and comparable global datasets has been a high priority in GEOTRACES from the beginning.
Protocols for sampling and analysis were developed early to ensure consistent data quality. The recommendations are summarized in the GEOTRACES cookbook, a valuable resource in many questions of sea water analysis.
The initially participating labs performed intercalibration exercises in order to ensure consistent analytical quality, published in L&O Methods. Newly joining labs can build on these efforts by intercalibrating with already intercalibrated labs. New exercises are being conducted as new parameters are added to GEOTRACES.
Elemental co-ordinators provide expertise on certain groups of analytes, often by providing reference (or consensus) materials, assisting with intercalibrating a lab, or as contact points for newly joining groups.
In addition to the general intercalibration of labs, all individual cruise data in GEOTRACES data products need to be intercalibrated with values from a crossover cruise following the intercalibration procedures, or following our defined alternative procedures. All TEI datasets going into a GEOTRACES data product from IDP2017 have been assessed by the Standards and Intercalibration Committee, based on the intercalibration report. The flow chart below illustrates how the S&I assess data quality for IDP.