Metadata Report for BODC Series Reference Number 2247938

• 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

Apollo Sci Tech AS-C3 Dissolved Inorganic Carbon (DIC)

A Dissolved Inorganic Carbon (DIC) analyser, for use in aquatic carbon dioxide parameter analysis of coastal waters, sediment pore-waters, and time-series incubation samples. The analyser consists of a solid state infrared CO2 detector, a mass-flow controller, and a digital pump for transferring accurate amounts of reagent and sample. The analyser uses an electronic cooling system to keep the reactor temperature below 3°C, and a Nagion dry tube to reduce the water vapour and keep the analyser drift-free and maintenance-free for longer. It is designed for both land based and shipboard laboratory use.

Specifications

Metrohm Aquatrode Plus with Pt1000 Combined pH electrode

Combined pH electrode with integrated Pt1000 temperature sensor for pH measurements/titrations in ion-deficient aqueous media (e.g., drinking water, process water). This electrode shows a very short response time in these samples. The fixed ground-joint diaphragm is insensitive to contamination. When c(KCl) = 3 mol/L is used as bridge electrolyte, storage in storage solution is recommended. The bridge electrolyte can be easily replaced with a chloride-free electrolyte (e.g., potassium nitrate c(KNO3) = 1 mol/L (6.2310.010)), storage in the used bridge electrolyte. Temperature range: 0 - 60 degC. pH range: 0 - 13.

For more information, please see this document: https://www.bodc.ac.uk/data/documents/nodb/pdf/Aquatrode_Plus_with_Pt1000_Metrohm.pdf

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.

CTD DIC and TA data for Cruise DY120

Originator's Protocol for Data Acquisition and Analysis

Sampling methodology

Water samples were taken according to Dickson et al., 2007, collected from a lowered CTD (conductivity, temperature and depth) rosette fitted with 12 Ocean Test Equipment (OTE) Niskin bottles, for analysis of dissolved inorganic carbon (DIC) and total alkalinity (TA) at select stations in the Rockall Trough. Samples were taken straight after the oxygen samples, to reduce contamination risk, into borosilicate 250 ml glass stopper bottles. Silicon tubing was flushed before the sample bottle was slowly filled and first inverted and then turned upright. The bottle was slowly rotated as it filled to make sure no bubbles collected inside the bottle. The bottle was over filled, the silicon tubing slowly removed and the stopper was inserted. After sampling was completed, back in the lab under a fume cupboard, 2.5 ml of seawater was removed from the bottle. 50 µl of 0.02 % mercuric chloride was then added into the seawater sample. The tip of the pipette was half its length below the surface of the seawater when doing this. Apieson grease was placed lightly around the inside neck of the bottle. With the glass bottle top on, the bottle was inverted to mix the sample before a loop of tightly stretched PVC tape was added around the bottle neck to seal the stopper. Details of the CTD station were added to the outside of the bottle with the seven digit code (e.g. 0103002 where: 1 = sample 1, 03 = Niskin number, 002 = CTD station number) and these were stored at room temperature. Samples were returned for shore-based analysis of dissolved inorganic carbon and total alkalinity. Each sample was analysed multiple times for dissolved inorganic carbon and total alkalinity, and a mean and standard deviation were calculated from this.

Analytical methodology

Water samples from the lowered rosette were analysed for: dissolved inorganic carbon and total alkalinity using a Apollo SciTech AS-C3 DIC analyser, and a Metrohm 848 Titrino Plus and Aquatrode electrode system respectively. Each sample for dissolved inorganic carbon and total alkalinity was analysed multiple times to produce a mean and standard deviation.

References Cited

Dickson A.G., Sabine C.L. and Christian J.R. (Eds.) 2007. Guide to Best Practices for Ocean CO2 Measurements. PICES Special Publication 3, 191 pp.

DY120 Cruise report

Further information can be found in the DY120 Cruise report.

BODC Data Processing Procedures

Data received were loaded into the BODC database using established BODC data banking procedures. Where data were provided by the originator as replicates the data were averaged and standard deviations calculated, leaving one measurement for each parameter per rosette position. The following bottle measurements for dissolved inorganic carbon and total alkalinity were provided in triplicate: CTD03 rosette position 19; CTD04 rosette position 7, 19; CTD08 rosette position 19. The following bottle measurements for dissolved inorganic carbon and total alkalinity were provided in duplicate: CTD10 rosette position 1, 3, 5, 9, 15, 19. Standard deviations (S.D.) were calculated using the formula:

sqrt(ε(x - mean(x))² /(n - 1)).

A parameter mapping table is provided below:

Project Information

UK - Overturning in the Subpolar North Atlantic Programme (UK-OSNAP) Programme

UK-OSNAP is part of an international collaboration to establish a transoceanic observing system in the subpolar North Atlantic. The aim is to quantify and understand the Subpolar Gyre's response to local and remote forcing of mass, heat and freshwater fluxes, within the conceptual framework of the Atlantic Meridional Overturning Circulation (AMOC).

UK-OSNAP is developing a new observing system to provide a continuous record of full-depth, trans-basin mass, heat, and freshwater fluxes. Combining these sustained measurements with innovative modelling techniques will enable the project to characterise the circulation and fluxes of the North Atlantic Subpolar Gyre.

UK-OSNAP is funded by the Natural Environment Research Council (NERC). The project is led by the National Oceanography Centre (NOC) with partners in the University of Liverpool, the University of Oxford and the Scottish Association for Marine Science (SAMS). It is a part of international OSNAP that is led by USA and includes 10 further partner groups in Canada, France, Germany, the Netherlands and China. The project involves fieldwork at sea and model studies.

The OSNAP observing system consists of two legs: one extending from southern Labrador to the southwestern tip of Greenland across the mouth of the Labrador Sea (OSNAP West), and the second from the southeastern tip of Greenland to Scotland (OSNAP East). The observing system also includes subsurface floats (OSNAP Floats) in order to trace the pathways of overflow waters in the basin and to assess the connectivity of currents crossing the OSNAP line.

NERC have added an extension to UK-OSNAP, until October 2024. This will result in the UK-OSNAP-Decade: 10 years of observing and understanding the overturning circulation in the subpolar North Atlantic (2014-2024). UK-OSNAP Decade forms part of the wider UK-OSNAP programme. Although supported through separate funding streams, including the Collective Funds 'Changing North Atlantic' grant, OSNAP decade (NE/T00858X/1), is considered a continuation of the core programme. In line with this, activities and associated data are grouped under UK-OSNAP, with funding details recorded here rather than as a separate project.

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for DY120_CTD_CTD02

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

Fixed Station Information

Ellett Line/Extended Ellett Line: Station M

Station M is one of the fixed CTD stations, which together form The Extended Ellett Line. The line lies between Iceland and the Sound of Mull (Scotland) crossing the Iceland Basin and Rockall Trough via the outcrop of Rockall. As part of this initiative, CTD dips, together with associated discrete sampling of the water column, have typically been carried out annually at this station since September 1996.

Prior to September 1996, Station M was part of a shorter repeated survey section, consisting of 35 fixed stations, known as The Ellett Line (originally termed the Anton Dohrn Seamount Section). This line incorporated those stations across the Rockall Trough and Scottish shelf between Rockall and the Sound of Mull and was visited at regular intervals (usually at least once a year) between 1975 and January 1996.

Related Fixed Station activities are detailed in Appendix 1

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: Ellett Line/Extended Ellett Line Station M

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

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