Standard Seawater Comparisons Updated

Abstract

Salinity adjustments that may reconcile differences in results from different expeditions are presented. These corrections are based upon batch-to-batch differences in Standard Seawater (SSW) after comparison with KC1-derived standards. Earlier SSW comparisons have shown that the chlorinity/conductivity relationship is not the same for all batches. Salinometers were standardized in terms of conductivity, while SSW was formerly labeled in terms of chlorinity. Labeling of SSW in terms of conductivity, relative to a standard KC1 solution was expected to eliminate SSW batch-to-batch differences. New SSW comparisons, presented below, reveal that while conductivity-labeled SSW batch-to-batch differences have been reduced, significant differences between batches persist. The new results have been adjusted relative to the KC1 standard as defined by the Practical Salinity Scale, 1978. In the past, it had not been possible to make absolute corrections to expedition salinities to account for SSW systematic errors because no absolute reference standard was available. It is now possible to account for SSW errors relative to a reproducible KC1 standard.