An Evaluation of Some Recent Batches of IAPSO Standard Seawater

Abstract

The authors examine changes in the salinity of the International Association for the Physical Sciences of the Ocean standard seawater (SSW) as used in seven cruises between 1991 and 1997. Ten batches of SSW were used during this time—several more than once—such that a clear demonstration of the effect of aging over months and years on SSW salinity can be made. Thus, the authors demonstrate that simple “offsets” intended to “correct” SSW salinity changes are inappropriate. Interest in intercruise salinity compatibility is high, as scientists attempt to reconcile section measurements made during the World Ocean Circulation Experiment among experiments. SSW salinity changes are one source of salinity differences of O(0.001) between sections. Herein, the authors provide a demonstration of how SSW measurements can be collated to generate a batch-by-batch history of SSW salinity evolution for more accurate sample salinity evaluation.