Metadata Report for BODC Series Reference Number 1851368

• 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

Methane and Nitrous Oxide as part of the ARABESQUE project

Parameter Code Definitions

Originator Codes

22 Prof. N.J.P. Owens Univ. of Newcastle

Originator Protocols

The dissolved seawater concentrations of nitrous oxide and methane (both important greenhouse gases) was determined simultaneously to high precision using a fully automated headspace equilibration gas chromatographic technique.

Samples were collected in 1 litre glass volumetric flasks and allowed to overflow by at least three volumes. Immediately following collection, the samples were stabilised by the addition of 200µl 0.25M aqueous mercuric chloride and the flasks were stoppered and inverted to disperse the HgCl₂. Analysis followed immediately; the samples were thermally equilibrated to 25°C in a water bath and then equilibrated with a headspace of known nitrous oxide and methane. The equilibrated gases were dried and passed over a Carbosorb column to remove CO₂ before being separated on Porapak Q columns and injected into the carrier gas lines (ultra high purity nitrogen) of two Shimadzu GC 8A gas chromatographs. The first was equipped with a flame ionisation detector (FID) for the analysis of methane; the second with an electron capture detector (ECD) for the measurement of nitrous oxide.

Two high mixing ratio primary standards were used for calibration, containing 10ppmv nitrous oxide, 5.2 ppmv methane and 20ppmv nitrous oxide, 8.5ppmv methane respectively. For routine calibrations, four secondary standards were prepared from these primary standards by pressure dilution (Upstill-Goddard et.al. 1990); estimates for their accuracy are 1.5% for methane and 2% for nitrous oxide. Analytical precisions are better than 0.5% for nitrous oxide and 0.4% for methane.

GO-FLO Bottle

A water sampling bottle featuring close-open-close operation. The bottle opens automatically at approximately 10 metres and flushes until closed. Sampling with these bottles avoids contamination at the surface, internal spring contamination, loss of sample on deck and exchange of water from different depths.

There are several sizes available, from 1.7 to 100 litres and are made of PVC with a depth rating of up to 500 m. These bottles can be attached to a rosette or placed on a cable at selected positions.

Project Information

ARABESQUE

ARABESQUE was a multidisciplinary oceanographic research project focused on the Arabian Sea and Northwest Indian Ocean during the monsoon and intermonsoon season in 1994. Funding for ARABESQUE was provided by the Ministry of Defence/ Defence Research Agency Joint Grant TQ/10/3/2 and Amersham International as well as the Natural Environment Research Council. ARABESQUE was almost entirely field based with extensive physical, chemical and biological measurements made in the Gulf of Oman, the Arabian Sea and the Northwest Indian Ocean. The aim of the project was to study the upper ocean microbial biogeochemistry in the Arabian Sea. Its focus was carbon and nitrogen cycling processes linked to climate change. The project was a UK contribution to the Joint Global Ocean Flux Study (JGOFS) Process Studies of the Arabian Sea. ARABESQUE was organised by Plymouth Marine Laboratory (PML).

Objectives

The detailed scientific objectives of ARABESQUE were to quantify the seasonal influence of the Monsoon winds in the Arabian Sea on:

• Upwelling of nutrients and the resultant production and fate of phytoplankton, in terms of size-fractionated, new and regenerated production

• Vertical and on-shelf gradients of heterotrophic, methanogenic and denitrifying bacteria

• Distribution of chemotaxonomic pigments with links to optical properties of seawater

• The Dissolved Inorganic and Organic Carbon cycle

• Air-sea exchange of Sulphur and Nitrogen biogases including dimethyl sulphide, methylamines and methane

• Sedimentation rates and the fate of organic matter through the oxygen depleted zone

A final objective was to calibrate satellite data on ocean colour so as to map the biogeochemistry of the northwestern Indian Ocean.

Fieldwork

The fieldwork programme consisted of two cruises of RRS Discovery. Cruise 210 (from 27 August to 4 October 1994) was timed to coincide with the South West Monsoon. Cruise 212 (from 16 November to 19 December 1994) took place during the intermonsoon period through to the onset of the North East Monsoon. The fieldwork programme included three repeated sections;

• One section along the Gulf of Oman

• A section at 8°N 67°E to 14° 30N 67°E

• A major section from 8°N 67°E to the coast of Oman

Other one-off sections were also crossed in the area. Sections were covered by underway upper ocean measurements and by a total of 21 sites where CTD/water-bottle stations were taken, 14 of which were repeated.

Data Management

Data management services to the ARABESQUE project were provided by the British Oceanographic Data Centre, funded by the UK Natural Environment Research Council.

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for DI210_CTD_AS1/5

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

Fixed Station Information

ARABESQUE - Oman Shelf Stations

The Oman Shelf stations (AS1 - AS5) lie within a box bounded by co-ordinates 19° 15.0'N, 58° 09.1'E at the southwest corner and 19° 30.0'N, 58° 35.4'E at the northeast corner. These represent five of the 20 ARABESQUE fixed stations illustrated in the map below.

ARABESQUE fixed stations were visited by 2 cruises, namely: RRS Discovery 210 (D210) - 25 August to 05 October 1994 and RRS Discovery 212 (D212) - 16 November to 19 December 1994. The cruises operated in survey and station mode: station mode consisted of profiling, production and trap stations.

More information is available via the D210 and D212 cruise reports.

Related Fixed Station activities are detailed in Appendix 2

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: DI210_CTD_AS1/5

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.

Appendix 2: ARABESQUE Oman Shelf

Related series for this Fixed Station 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.