Metadata Report for BODC Series Reference Number 2055346

• 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

Digitron 2000 series 2028T Thermometer

Digitron 2000 series are a range of hand-held digital thermometers. The 2028T model presents readings in seconds with an accuracy of 0.2%. Digitron provide a unique SpeedRead feature which supplies an answer in 14 seconds or if this measurement cannot be made the instrument automatically reverts back to a standard thermometer accuracy. Additional features of the Digitron 2000 series include logging mode for storage, retrieval and output of readings and a long battery life of approximately 500 hours. The 2028T thermometer provides Celsius or Fahrenheit function and has a temperature range of 200°C to +1350°C/ -328°F to +2462°F.

Common specifications of the instrument can be found in the table below:

Further information can be found in the manufacturers manual.

Additional information can also be found on the technical data 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.

Carbonate chemistry - pH from CTD bottles during AMT21(D371)

Originator's Protocol for Data Acquisition and Analysis

As part of the Atlantic Meridional Transect (AMT) (AMT 21) a total of 74 CTD casts were obtained onboard the D371 cruise. This annual return passage from the UK to the Falkland Islands took place from September to November 2011.

Samples were obtained from each of the 74 CTD positions. CTD casts were recorded using the Sea-Bird data collection software Seasave-Win32. The software outputs were then processed following the BODC recommended guidelines using SBE Data ProcessingWin32 v7.20g

pH samples (total scale) were collected from the CTD hydrocast using 250 mL amber glass bottles. pH was determined using a Perkin-Elmer Lambda 35 spectrophotometer which measured the absorbance at 434, 578 and 730 nm with a 10 cm quartz cuvette. The samples were initially placed in a water bath at 25°C to achieve temperature equilibration. A 2 mmol/L solution of m-cresol purple (Sigma-Alrich, product number: 857890-5G) was prepared for spectrophotometric pH determination, with 100 µL of this dye solution added directly to the cuvette. Absorbance, before and after the addition of the dye solution, was measured. A pH correction for the dye supplement was applied using the method in Dickson et al. (2007).

In-situ pH (total scale) was calculated using CO2SYS software following a protocol obtained from Dickson et al. (2007). Temperature within the spectrophotometer, which was measured throughout the analysis, was recorded using a Digitron 2028T thermometer.

References Cited

Dickson, A.G., Sabine, C.L., Christion, J.R., 2007. Guide to best practices for ocean CO2 measurements. PICES Special Publication 3, PICES Special Publication 3, p. 191.

D371 Cruise report

Further information can be found in the D371 Cruise report.

BODC Data Processing Procedures

The data arrived at BODC in excel format representing data collected from the 74 CTD stations. The data were loaded into the BODC database using established BODC data banking procedures. Supplied replicate samples were averaged and the standard deviation calculated before loading into the database. The data were mapped to BODC parameter codes.

Project Information

Oceans 2025 Theme 10, Sustained Observation Activity 1: The Atlantic Meridional Transect (AMT)

The Atlantic Meridional Transect has been operational since 1995 and through the Oceans 2025 programme secures funding for a further five cruises during the period 2007-2012. The AMT programme began in 1995 utilising the passage of the RRS James Clark Ross between the UK and the Falkland Islands southwards in September and northwards in April each year. Prior to Oceans 2025 the AMT programme has completed 18 cruises following this transect in the Atlantic Ocean. This sustained observing system aims to provide basin-scale understanding of the distribution of planktonic communities, their nutrient turnover and biogenic export in the context of hydrographic and biogeochemical provinces of the North and South Atlantic Oceans.

The Atlantic Meridional Transect Programme is an open ocean in situ observing system that will:

• give early warning of any fundamental change in Atlantic ecosystem functionng
• improve forecasts of the future ocean state and associated socio-economic impacts
• provide a "contextual" logistical and scientific infrastructure for independently-funded national and international open ocean biogeochemical and ecological research.

The specific objectives are:

• To collect hydrographic, chemical, ecological and optical data on transects between the UK and the Falkland Islands
• To quantify the nature and causes of ecological and biogeochemical variability in planktonic ecosystems
• To assess the effects of variability in planktonic ecosystems on biogenic export and on air-sea exchange of radiatively active gases

The measurements taken and experiments carried out on the AMT cruises will be closely linked to Themes 2 and 5. The planned cruise track also allows for the AMT data to be used in providing spatial context to the Sustained Observation Activities at the Porcupine Abyssal Plain Ocean Observatory (SO2) and the Western Channel Observatory (SO10).

More detailed information on this Work Package is available at pages 6 - 9 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10

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

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for D371_CTD_CTD069

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.

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: D371_CTD_CTD069

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

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.