The Committee concluded that the agreement between data examined is reasonable
The Standards and Intercalibration (S&I) Committee is one of the two standing committees in GEOTRACES, the other being Data Management. The Committee’s charge is to ensure that accurate and precise data are generated in the GEOTRACES Program through the use of appropriate sampling protocols, analytical standards and certified reference materials, and the active sharing of methods and results so that everyone gets the “same number” – this latter item is intercalibration. But how do we do this?
Since the concentration, activity, or chemical speciation of a trace element or isotope can be affected by sampling methods, sample handling, and analytical determinations, the S&I Committee decided the best way for GEOTRACES to ensure accuracy was for the various cruises to occupy a common station along their transects, either ad hoc ones (“Crossover Stations”) or long standing stations that have been occupied many times by many different cruises – two of these Baseline Stations were established during the 2008 (Atlantic) and 2009 (Pacific) Intercalibration Cruises. Simple data comparisons like depth profiles show whether there are disagreements, and if so, the investigators can examine their methods and even data work ups to identify and remedy the problems, again, intercalibration.
The first of these meetings was hosted by Maeve Lohan at the University of Plymouth, UK, 6-9 March 2012. The Committee examined data from 6 crossover stations in the Atlantic Ocean that were sampled in 2009 – 2011. Including the hydrographic salinity, oxygen, and nutrient data, this meeting examined over 3600 data points! But, it is important to remember that these were actually only a portion of the data that are still being generated – the radionuclide and particulate results are not yet available for most of the cruises. In general, the agreements between the vast array of trace elements and isotopes examined in GEOTRACES were good, and for those that were not, the investigators who have received our reports will continue to intercalibrate with their crossover partners to generate the best possible results.
S&I Committee Members: Gregory Cutter (Chair), Per Andersson, Louis Codispoti, Peter Croot, Roger Francois, Maeve Lohan, Hajime Obata, and Michiel van der Loeff.