Metadata Report for BODC Series Reference Number 1207465

• 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

AMT20 (JC053) Continuous Underway Dissolved Hydrogen Data Quality Document

A few isolated spikes occur throughought the data with more noise towards the end of the cruise.

A few longitudes were flagged as null data ('N') during the transfer where no longitude existed in the original submission.

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

Trace Analytical RGA3 reduction gas analyser

A mercuric oxide reduction gas analyser which detects H₂ and CO. Methodology is gas chromatography followed by the reduction of mercuric oxide. Mercury vapour from this reaction is detected by UV absorption. Trace Analytical Inc. was acquired by Ametek Process Instruments in 2004. The instrument is no longer manufactured.

AMT20 (JC053) Continuous Underway Dissolved Hydrogen Instrumentation

Instrument Description

The underway system used to continuously measure the dissolved hydrogen concentration was based on the equilibrator described in Xie et al., 2001. The actual measurement was completed by a Reduced Gas Analyser (RGA3), Trace Analytical Inc.

Reference

Xie, H., Zafiriou, O. C., Wang, W. and Taylor, C. D. 2001. A simple automated continuous-flow-equilibration method for measuring carbon monoxide in seawater. Environmental Science and Technology. 35, 1475-1480.

AMT20 (JC053) Dissolved Hydrogen Concentration - Continuous Measurement from Surface Waters

Data Acquisition and Analysis

A new method of equilibrating seawater samples for Hydrogen measurement was employed for the AMT20 cruise allowing H₂ to be measured from underway samples every 3.5 minutes. Underway samples were pumped from a depth of around 7 m, through the ship's non-toxic system, at a continuous flow rate of 1 L min^-1 to a reservoir. A sample of this was then pumped to the equilibrator at approximately 14 mL min^-1. An air segmented, continuous flow equilibrator similar to that developed by Xie et al. (2001) was used to obtain a gaseous sample from the seawater. Hydrogen measurements of the gaseous sample were made with a gas chroatograph that incorporated a reducing compound photometer. For each measurement, a chromatograph was generated from which a peak was produced. The peak from the chromatograph was compared to the peak from a reference gas it was then possible to calculate. The Hydrogen concentration of the sample was calculated by comparing chromotograph peaks from samples to peaks from known referencegas standards.

BODC Data Processing

Data were submitted to BODC as an Excel .xlsx file, containing the data and metadata, alongside a word document, containing the methodology. The data were then saved as two .csv files, one containing the data and the other containing the metadata. The data were then transferred to the BODC format and loaded to the database.

Parameter codes defined in the BODC parameter dictionary were assigned to the variable as shown in the table below:

Screening

Data were screened using in-house software, using the BODC flagging system. A few spikes were flagged as suspect ('M').

Reference:

Xie, H., Zafiriou, O. C., Wang, W. and Taylor, C. D. 2001. A simple automated continuous-flow-equilibration method for measuring carbon monoxide in seawater. Environmental Science and Technology. 35, 1475-1480.

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

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: