Metadata Report for BODC Series Reference Number 1868595

• 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

Public domain 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.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

Non-toxic (underway) sea water supply

A source of uncontaminated near-surface (commonly 3 to 7 m) seawater pumped continuously to shipboard laboratories on research vessels. There is typically a temperature sensor near the intake (known as the hull temperature) to provide measurements that are as close as possible to the ambient water temperature. The flow from the supply is typically directed through continuously logged sensors such as a thermosalinograph and a fluorometer. Water samples are often collected from the non-toxic supply. The system is also referred to as the underway supply.

Methane for cruises Meteor M27_1, Belgica BG9506 and Poseidon PS211

Document History

Converted from CDROM documentation.

Content of data series

Data Originator

Professor Robin Keir, GEOMAR, Kiel, Germany.

Sampling strategy and methodology

Water samples were collected from the CTD rosette and analysed on board ship for dissolved methane. The gas phase was obtained by two methods. The first involved a partial separation of gas and water phases under vacuum using repeated application of ultrasound. The second utilised equilibration of the water sample with a small volume of added pure nitrogen head space. Dissolved methane was then computed from the measured gas phase mixing ratio and the methane solubility at the laboratory conditions of temperature and salinity.

Measurements of surface dissolved methane were obtained as a by-product of the underway pCO₂ determination. Surface sea water (from an inlet in the bow of Belgica or the 'moon pool' of Poseidon) was continuously pumped through the gas equilibrator where the dissolved gases exchanged with a closed loop of air. The gas loop was sampled periodically (approximately every 10 minutes) and the CO₂ separated from the methane by the GC column. The CO₂ was then reduced by hydrogen over a nickel catalyst and analysed as methane. This resulted in two peaks that could be quantified separately for methane and carbon dioxide.

Air samples were collected periodically (approximately hourly) from an inlet mounted on the bow of the ship and analysed in the same way as the equilibrated gases.

The surface methane data were reduced by the data originator to average values for each one degree square traversed by the ship. The data in this reduced form could be loaded into the database for Poseidon PS211 because the cruise track was a simple straight line. However, Belgica passed through a number of squares several times during the cruise making loading of the spatially averaged data impossible. Consequently, the full raw data set (water samples every 10 minutes with an air sample approximately every hour) has been loaded for this cruise.

Project Information

Ocean Margin EXchange (OMEX) I

Introduction

OMEX was a European multidisciplinary oceanographic research project that studied and quantified the exchange processes of carbon and associated elements between the continental shelf of western Europe and the open Atlantic Ocean. The project ran in two phases known as OMEX I (1993-1996) and OMEX II - II (1997-2000), with a bridging phase OMEX II - I (1996-1997). The project was supported by the European Union under the second and third phases of its MArine Science and Technology Programme (MAST) through contracts MAS2-CT93-0069 and MAS3-CT97-0076. It was led by Professor Roland Wollast from Université Libre de Bruxelles, Belgium and involved more than 100 scientists from 10 European countries.

Scientific Objectives

The aim of the Ocean Margin EXchange (OMEX) project was to gain a better understanding of the physical, chemical and biological processes occurring at the ocean margins in order to quantify fluxes of energy and matter (carbon, nutrients and other trace elements) across this boundary. The research culminated in the development of quantitative budgets for the areas studied using an approach based on both field measurements and modeling.

OMEX I (1993-1996)

The first phase of OMEX was divided into sub-projects by discipline:

• Physics
• Biogeochemical Cycles
• Biological Processes
• Benthic Processes
• Carbon Cycling and Biogases

This emphasises the multidisciplinary nature of the research.

The project fieldwork focussed on the region of the European Margin adjacent to the Goban Spur (off the coast of Brittany) and the shelf break off Tromsø, Norway. However, there was also data collected off the Iberian Margin and to the west of Ireland. In all a total of 57 research cruises (excluding 295 Continuous Plankton Recorder tows) were involved in the collection of OMEX I data.

Data Availability

Field data collected during OMEX I have been published by BODC as a CD-ROM product, entitled:

• OMEX I Project Data Set (two discs)

Further descriptions of this product and order forms may be found on the BODC web site.

The data are also held in BODC's databases and subsets may be obtained by request from BODC.

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: