Ocean Science A global algorithm for estimating Absolute Salinity

• Main Authors: T. J. Mcdougall, D. R. Jackett, F. J. Millero, R. Pawlowicz, P. M. Barker
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2012
• Subjects: Pacific; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.452.7891; http://www.ocean-sci.net/8/1123/2012/os-8-1123-2012.pdf

Abstract. The International Thermodynamic Equation of Seawater – 2010 has defined the thermodynamic properties of seawater in terms of a new salinity variable, Absolute Salinity, which takes into account the spatial variation of the composition of seawater. Absolute Salinity more accu-rately reflects the effects of the dissolved material in seawater on the thermodynamic properties (particularly density) than does Practical Salinity. When a seawater sample has standard composition (i.e. the ratios of the constituents of sea salt are the same as those of surface water of the North Atlantic), Practical Salinity can be used to accurately evaluate the thermodynamic proper-ties of seawater. When seawater is not of standard compo-sition, Practical Salinity alone is not sufficient and the Ab-solute Salinity Anomaly needs to be estimated; this anomaly is as large as 0.025 g kg−1 in the northernmost North Pacific. Here we provide an algorithm for estimating Absolute Salin-ity Anomaly for any location (x,y,p) in the world ocean. To develop this algorithm, we used the Absolute Salinity Anomaly that is found by comparing the density calculated from Practical Salinity to the density measured in the labora-tory. These estimates of Absolute Salinity Anomaly however are limited to the number of available observations (namely 811). In order to provide a practical method that can be used at any location in the world ocean, we take advantage of ap-proximate relationships between Absolute Salinity Anomaly and silicate concentrations (which are available globally). 1