Metadata Report for BODC Series Reference Number 1988721

• 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 supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."

Narrative Documents

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.

Turner Designs Trilogy Fluorometer

The Trilogy Laboratory Fluorometer is a compact laboratory instrument for making fluorescence, absorbance and turbidity measurements using the appropriate snap-in Application Module.

The following snap-in application modules are available:

For extracted chlorophyll measurements using EPA 445, Trilogy automatically calculates the concentration using the filtered and solvent volumes. The turbidity modules use an IRLED with a wavelength of 860nm to meet ISO 7027 standards for turbidity water quality measurements.

Specifications

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

D340B Discrete Chlorophyll-a and Phaeophytin-a Sampling Document

Originator's Protocol for Data Acquisition and Analysis

Water samples were collected from CTD stations throughout the cruise for the analysis of chlorophyll-a and phaeophytin-a. The decision of where to fire the CTD rosette bottles took into account the position of the chlorophyll maximum, as observed from the fluorometer sensor, during the downcast.

Samples were drawn from the CTD Niskin bottles into one litre pre-washed polycarbonate bottles. Subsamples were taken from these and filtered through 47 mm GF/F glass fibre filters using a vacuum pump. Filter papers were carefully removed, placed in centrifuge tubes and frozen for analysis back in the laboratory.

Analysis involved the extraction of chlorophyll overnight using 90% acetone at a constant temperature of 4 °C. Samples were then sonicated and centrifuged to release pigment into solution, with concentrations being measured using a Turner Designs Trilogy fluorometer.

Samples were also taken from the vessel's underway non-toxic water supply, approximately every four hours. These samples were used to compare with the output of the underway fluorometer.

BODC Data Processing Procedures

The chlorophyll data were supplied to BODC in Microsoft Excel format. Values were extracted from this and loaded into BODC's ocean database under the ORACLE Relational Database Management System. Data that were considered unrealistic were flagged suspect.

It should be noted that for cast C088 a chlorophyll sample was taken from a depth of 22m. Four bottles were fired at this depth for C088 but the cruise report log sheets do not indicate which bottle the sample was taken from. In this instance the data have been assigned to bottle 5 but users should be aware that bottles 6, 7 and 8 were also fired at this depth.

Content of data series

References Cited

Inall, M. E., (2009) 'Cruise D340B Dunstaffnage to Govan via Barra Head and the Surrounding Shelf', Internal Report No 265, Scottish Association for Marine Science.

Available - Cruise D340B Internal Report

Project Information

Oceans 2025 Theme 3: Shelf and Coastal Processes

Over the next 20 years, UK local marine environments are predicted to experience ever-increasing rates of change - including increased temperature and seawater acidity, changing freshwater run-off, changes in sea level, and a likely increase in flooding events - causing great concern for those charged with their management and protection. The future quality, health and sustainability of UK marine waters require improved appreciation of the complex interactions that occur not only within the coastal and shelf environment, but also between the environment and human actions. This knowledge must primarily be provided by whole-system operational numerical models, able to provide reliable predictions of short and long-term system responses to change.

However, such tools are only viable if scientists understand the underlying processes they are attempting to model and can interpret the resulting data. Many fundamental processes in shelf edge, shelf, coastal and estuarine systems, particularly across key interfaces in the environment, are not fully understood.

Theme 3 addresses the following broad questions:

• How do biological, physical and chemical processes interact within shelf, coastal and estuarine systems, particularly at key environmental interfaces (e.g. coastline, sediment-water interface, thermocline, fronts and the shelf edge)?
• What are the consequences of these interactions on the functioning of the whole coastal system, including its sensitivity and/or resilience to change?
• Ultimately, what changes should be expected to be seen in the UK coastal environment over the next 50 years and beyond and how might these changes be transmitted into the open ocean?

Within Oceans 2025, Theme 3 will develop the necessary understanding of interacting processes to enable the consequences of environmental and anthropogenic change on UK shelf seas, coasts and estuaries to be predicted. Theme 3 will also provide knowledge that can improve the forecasting capability of models being used for the operational management of human activities in the coastal marine environment. Theme 3 is therefore directly relevant to all three of NERC's current strategic priorities; Earth's Life-Support Systems, Climate Change, and Sustainable Economies

The official Oceans 2025 documentation for this Theme is available from the following link: Oceans 2025 Theme 3

Weblink: http://www.oceans2025.org/

Oceans 2025 Theme 3, Work Package 3.7: Role of Topography in Determining the Spatial Variability in Horizontal Dispersion

Tracer and budget studies show that mixing and exchange of oceanic and coastal water take place on the shelf. Topographic features, such as banks, slopes and troughs enhance horizontal and vertical mixing on scales of a few kilometres. This is presently too small to be fully resolved by existing shelf models but not by the next generation. However, for this to occur, processes that drive the mixing between terrestrial runoff and oceanic water, e.g. tidal stirring and straining, inertial currents, eddy activity and internal waves need to be explicitly included or parameterised.

Internal waves are assumed to dominate velocity and density variations on scales <100 m. Two-dimensional geostrophic horizontal turbulence ("vortical modes") exists at similar and larger scales and is relatively well understood, in isolation. However, the dispersive effects of interactions between vortical modes and internal wave mixing are poorly understood. Both internal waves and vortical mode activity are influenced by topography. Work Package (WP) 3.7, managed by the Scottish Association for Marine Science (SAMS) aims to investigate topographic regime control on horizontal dispersion mediated by internal wave/vortical mode interactions on the continental shelf.

The specific objectives are:

• Assess and quantify how horizontal dispersion through shelf seas is affected by irregular seabed topography
• Deliver an understanding on what the rate limiting processes are in the horizontal dispersion and exchange and mixing rates of stratified shelf waters

More detailed information on this WP is available at pages 14 - 15 of the official Oceans 2025 Theme 3 document: Oceans 2025 Theme 3

Weblink: http://www.oceans2025.org/

Data Activity or Cruise Information

Data Activity

No Document Information Held for the Series

Related Data Activity activities are detailed in Appendix 1

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:

Appendix 1: D340B_CTD_C092

Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.

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