Metadata Report for BODC Series Reference Number 2243359

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data Access Policy

Open Data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."

Narrative Documents

Guildline Autosal 8400 salinometers

Guildline 8400 Autosals are bench salinometers that are used to determine the salinity of a water sample by comparison of its electrical conductivity with a standard solution. The instruments employ a continuous flow system, whereby a sample is drawn into the unit under low air pressure. The sample is pumped into conductivity cells where the conductivity ratio is measured, allowing derivation of salinity. A high stability temperature controlled bath and heat exchanger maintain the sample at a precisely defined, user-selected temperature during analysis, avoiding the need for temperature compensation.

Specifications

Guildline have produced two models of the 8400 Autosal: the earlier 8400A had an external interface as an optional extra. The 8400B has the external interface fitted as standard, and has improved stability over long periods.

Further details can be found in the manufacturer's specification sheet

Niskin Bottle

The Niskin bottle is a device used by oceanographers to collect subsurface seawater samples. It is a plastic bottle with caps and rubber seals at each end and is deployed with the caps held open, allowing free-flushing of the bottle as it moves through the water column.

Standard Niskin

The standard version of the bottle includes a plastic-coated metal spring or elastic cord running through the interior of the bottle that joins the two caps, and the caps are held open against the spring by plastic lanyards. When the bottle reaches the desired depth the lanyards are released by a pressure-actuated switch, command signal or messenger weight and the caps are forced shut and sealed, trapping the seawater sample.

Lever Action Niskin

The Lever Action Niskin Bottle differs from the standard version, in that the caps are held open during deployment by externally mounted stainless steel springs rather than an internal spring or cord. Lever Action Niskins are recommended for applications where a completely clear sample chamber is critical or for use in deep cold water.

Clean Sampling

A modified version of the standard Niskin bottle has been developed for clean sampling. This is teflon-coated and uses a latex cord to close the caps rather than a metal spring. The clean version of the Levered Action Niskin bottle is also teflon-coated and uses epoxy covered springs in place of the stainless steel springs. These bottles are specifically designed to minimise metal contamination when sampling trace metals.

Deployment

Bottles may be deployed singly clamped to a wire or in groups of up to 48 on a rosette. Standard bottles and Lever Action bottles have a capacity between 1.7 and 30 L. Reversing thermometers may be attached to a spring-loaded disk that rotates through 180° on bottle closure.

DY157 Discrete Salinity Sampling - CTD sensor calibration

Originator's Protocol for Data Acquisition and Analysis

Sampling methodology

Discrete salinity samples were collected on 56 CTD casts performed on cruise DY157. All casts were conventional profiling casts with 24 x 20L Ocean Test Equipment (OTE) Niskin bottles for sampling water. Between casts the whole CTD package was rinsed with fresh water with particular attention paid to the SBE 32 latch assembly. After each cast the primary and secondary sensors were flushed three times with MilliQ. Periodically the optical sensors were cleaned with MilliQ and Optic Prep wipes. The salinity channels were calibrated against bench salinometer measurements from four samples collected from each CTD cast.

Analytical methodology

A Guildline 8400B, s/n 68958 was installed in the Salinometer Room as the main Autosal for salinity analysis. The bath temperature was set to 21°C with the lab ambient temperature ranging between 18°C-19°C. The salinometer was standardised prior to the start of analysis. The Autosal was standardised using IAPSO Standard Seawater batch P164 (K15 = 0.9985, 2 x K15 = 1.99970). Crate 31 was analysed first, the standard read high at 1.99976 at the start of the run and increased to 1.99989 by the end of the crate. The Autosal was standardised again before any further analysis, the pot was adjusted to give a reading of 1.99969. The final standard of the cruise read 1.99978 showing a slight increase. To generate a calibration, an offset between the discrete water sample measurement (salinity) and the nominal value from the sensor at bottle firing was calculated. Outliers were identified using plots of offset against the discrete sample values and a linear regression was applied.

DY157 Cruise report

Further information can be found in the DY157 Cruise report.

BODC Data Processing Procedures

Data received were loaded into the BODC database using established BODC data banking procedures. A parameter mapping table is provided below:

Project Information

Marine LTSS: CLASS (Climate Linked Atlantic Sector Science)

Introduction

CLASS is a five year (2018 to 2023) programme, funded by the Natural Environment Research Council (NERC) and extended until March 2024.

Scientific Rationale

The ocean plays a vital role in sustaining life on planet Earth, providing us with both living resources and climate regulation. The trajectory of anthropogenically driven climate change will be substantially controlled by the ocean due to its absorption of excess heat and carbon from the atmosphere, with consequent impacts on ocean resources that remain poorly understood. In an era of rapid planetary change, expanding global population and intense resource exploitation, it is vital that there are internationally coordinated ocean observing and prediction systems so policy makers can make sound evidence-based decisions about how to manage our interaction with the ocean. CLASS will underpin the UK contribution to these systems, documenting and understanding change in the marine environment, evaluating the impact of climate change and effectiveness of conservation measures and predicting the future evolution of marine environments. Over the five-year period CLASS will enhance the cost-effectiveness of observing systems by migrating them towards cutting edge autonomous technologies and developing new sensors. Finally, CLASS will create effective engagement activities ensuring academic partners have transparent access to NERC marine science capability through graduate training partnerships and access to shipborne, lab based and autonomous facilities, and modelling capabilities.

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for DY157_CTD_CTD033

Please note:the supplied parameters may not have been sampled from all the bottle firings described in the table above. Cross-match the Sample Reference Number above against the SAMPRFNM value in the data file to identify the relevant metadata.

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

No Fixed Station Information held for the Series

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle: