Bench salinometer measurements from CTD bottle samples collected during AMT13
Originator's Protocol for Data Acquisition and Analysis
During the cruise up to three salinity samples were drawn from the CTD Niskin bottles after 12 casts. Where possible two samples were taken from the two deepest sampled depths and one from the surface. This was to avoid, as far as possible, sampling in regions of strong stratification.
Samples were taken using 200 ml glass sample bottles that were rinsed three times in the sample water and filled to the shoulder. The inside of the bottle neck, plastic insert and bottle cap were dried and the bottle then sealed.
A Guildline 8400B Laboratory Salinometer fitted with a peristaltic pump was used to determine the salinity of all bottle samples. The salinometer was located in the Prep Laboratory and operated at 24°C bath temperature and 21-24°C ambient lab temperature. All samples were processed according to WOCE standards and protocols.
The salinometer appeared to work well for the first batch of samples but failed to keep a constant reading later in the cruise. It was decided to return samples to the UK to run them on the UKORS salinometer after the cruise.
References Cited
Instrumentation Description
Guildline 8400B Laboratory Salinometer
BODC Data Processing Procedures
Data were submitted in two Excel spreadsheets and archived under BODC's accession number RVS030093. One file contained the data from the cruise and the other from the samples run after the cruise. In each file the only identifiers were the salinity sample bottle ID. These were matched to sample metadata (cast number, Niskin bottle and depth) from the CTD bottle firing logsheets supplied post cruise to BODC. The cast number, Niskin bottle number and depth were used to match the data to the metadata in the database. There were two discrepancies - for cast 20 the two bottles fired were match by depth not Niskin bottle number.
No unit conversion was necessary as the units the data were supplied in the files matched the units for the parameter codes in the BODC Parameter Dictionary.
A parameter mapping table is provided below;
Originator's Parameter | Units | Description | BODC Parameter Code | Units | Comments |
---|---|---|---|---|---|
Salinity | Dimensionless | Practical salinity of the water body by bench salinometer and computation using UNESCO 1983 algorithm | PSALBSTX | Dimensionless | n/a |
Salinity | Dimensionless | Practical salinity standard deviation of the water body by bench salinometer | PSSDBSTX | Dimensionless | n/a |
Data Quality Report
The data values provided from during the cruise have been flagged suspect as per the notes in the cruise report from the data originator. The data provided from samples run back in Southampton after the cruise, with the exception of 1 data point, were OK and used for the sensor calibrations. The suspect data point has been flagged accordingly.
Problem Report
Not relevant to this data set.