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Extended Ellett Line Bottle Salinity Series for RRS Discovery cruise D312

Originator's Data Acquisition and Analysis

Salinity samples were drawn from Niskin bottles mounted on the CTD rosette at depths determined by the PSO or Watch Leader. The Niskin bottles were typically fired away from salinity gradients in an attempt to gain a stable measurement.

Salinity samples were taken in 200 ml glass sample bottles, rinsed three times and sealed with disposable plastic stoppers and screw on caps after drying the neck. Samples were stored in the CT laboratory for a minimum of 24 hours before analysis to allow equilibration to the laboratory temperature.

All salinity sample analysis was performed on a Guildline Autosal salinometer (8400B serial no. 60839) in the Constant Temperature (CT) laboratory. The laboratory temperature was maintained at 21°C. Standardisation of Autosal was performed using IAPSO standard seawater (batch P145, K15 value of 0.99981) and was done prior to the analysis of each crate. Standard seawater samples were also analysed at the end of every crate as a quality check.

OSIL's Autosal software, Softsal was used to process the raw data. Calibrated data was transfer to the UNIX system and a routine was performed to incorporate the data into the PSTAR sam files, which were supplied to BODC for banking.

BODC processing

The data were received in 64 pstar files which were loaded into the BODC database using established BODC data banking procedures without any changes.

The mapping between the originator's channels and BODC parameter codes is detailed in the table below.

Originator's Parameter Unit Description BODC Parameter Code BODC Unit Comments
botsal - Practical salinity of the water body PSALBSTX Dimensionless n/a

Data Quality Report

There was a slight drift in the data that occurs between stations 16143 and 16148, the problem seemed to lie in the CTD sensor calibration