Metadata Report for BODC Series Reference Number 696559

• 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

James Clark Ross 106b - Autosub AquaLAB delta18O BODC Data Processing

The data were received by BODC in the Matlab .MAT binary format. They were transferred to BODC's QXF format using transfer procedure 390. The table below shows the mapping between the variables include in the submitted data file and BODC's parameter dictionary codes used in the QXF.

It should be noted that the time, position and pressure of the sample were recorded halfway through the sampling procedure, which takes approximately 20 minutes, during which time the Autosub may travel up to 2.5 km.

Following the transfer to QXF, the data were screened using BODC's in-house visualisation software, EDSERPLO. No problems were found with the data.

James Clark Ross 106b - Autosub AquaLAB delta18O Originator's Data Processing

The AquaLAB water sampler was deployed from the Autosub autonomous underwater vehicle during cruise JCR106b to collect water samples from the mouth of Kangerdlussaq Fjord, East Greenland (68°N, 32°W). The aim was to examine the ratio of oxygen isotopes ¹⁶O and ¹⁸O in the sampled sea water compared with Vienna Standard Mean Ocean Water (VSMOW).

Prior to deployment of the AquaLAB sampler it was essential to ensure that no water, other than the "prime" water, was left in the sampling bags of the instrument. "Prime" water is contained in the sample bags until the sample is collected in order to prevent the sample bags being crushed, and therefore damaged, by hydrostatic pressure as the Autosub dived to depth during its mission. The procedure outlined below was followed to ensure that the AquaLAB was correctly prepared for deployment:

• A 25 litre carboy (a glass or plastic container enclosed by a special container) was flushed and filled with surface sea water from the James Clark Ross' uncontaminated surface water supply for use as a prime.
• Salinity, barium and oxygen isotope samples were taken from the carboy after filling to determine the properties of the surface water.
• For Autosub mission 377, the surface water had a salinity of 30.862, and an ¹⁶O:¹⁸O ratio of -2.23% relative to VSMOW
• The sample bags were then flushed three times with water from the carboy, after which 30 ml of water from the carboy was added to each bag.
• AquaLAB's mechanical syringe and rotary valve were then flushed with water from the carboy.
• A second set of salinity and trace element measurements were then taken from the carboy in order to monitor any changes which may have taken place during the procedure.

After the recovery of the AquaLAB, the water samples were transferred from the AquaLAB's sample bags to two 50 ml bottles. The samples were later tested for their ¹⁶O:¹⁸O ratio compared to VMSOW by using a stable isotope mass spectrometer.

Stable isotope mass spectrometry makes use of the knowledge that the lighter elements of the periodic table (particularly carbon, hydrogen, nitrogen, oxygen and sulphur) occur naturally with more than one atomic mass (the isotopes). As these isotopes do not decay radioactively, they are known as stable isotopes. The mass spectrometer measures the atomic mass of the isotopes present in the sample relative to a standard of known isotopic composition. From these results, the isotopic ratio can be calculated.

Reference

Dodd, P.A., Price, M.R., Heywood, K.J. and Pebody, M. (2006). Collection of water samples from an autonomous underwater vehicle for tracer analysis. Journal of Atmospheric and Oceanic Technology 23(12): 1759-1767

AquaLAB Instrument Description

EnviroTech LLC's AquaLAB is a deep-ocean (up to 6000m) gas tight water sampler capable of collecting 50 samples of up to 1 litre in volume. The samples are collected using a high-integrity 50-port rotary valve and injected into titanium foil or flexible but inelastic medical ethylene vinyl acetate (EVA) bags. The samples are then stored within the instrument for post-recovery analysis.

The sampler is controlled by an onboard computer, which can be programmed to either take samples at pre-determined intervals or when an external controller issues a command to take a sample.

The AquaLAB sampler has been used to:

• Sample water for trace gas analysis (e.g. CFC, C0₂,SF₆)
• Sample water during extended deployments of up to one year
• Determine salinity very accurately
• Analyse water quality parameters such as nutrient concentration

Specification

Project Information

AutoSub Under Ice (AUI) Programme

AutoSub was an interdisciplinary Natural Environment Research Council (NERC) thematic programme conceived to investigate the marine environment of floating ice shelves with a view to advancing the understanding of their role in the climate system.

The AUI programme had the following aims:

• To attain the programme's scientific objectives through an integrated programme based on interdisciplinary collaborations and an international perspective
• To develop a data management system for the archiving and collation of data collected by the programme, and to facilitate the eventual exploitation of this record by the community
• To provide high-quality training to develop national expertise in the use of autonomous vehicles in the collection of data from remote environments and the integration of such tools in wider programmes of research
• To stimulate and facilitate the parameterising of sub-ice shelf processes in climate models, and to further demonstrate the value of autonomous vehicles as platforms for data collection among the wider oceanographic and polar community

Following the invitation of outline bids and peer review of fully developed proposals, eight research threads were funded as part of AUI:

Physical Oceanography

• ISOTOPE: Ice Shelf Oceanography: Transports, Oxygen-18 and Physical Exchanges.
• Evolution and impact of Circumpolar Deep Water on the Antarctic continental shelf.
• Oceanographic conditions and processes beneath Ronne Ice Shelf (OPRIS).

Glaciology and Sea Ice

• Autosub investigation of ice sheet boundary conditions beneath Pine Island Glacier.
• Observations and modelling of coastal polynya and sea ice processes in the Arctic and Antarctic.
• Sea ice thickness distribution in the Bellingshausen Sea.

Geology and Geophysics

• Marine geological processes and sediments beneath floating ice shelves in Greenland and Antarctica: investigations using the Autosub AUV.

Biology

• Controls on marine benthic biodiversity and standing stock in ice-covered environments.

The National Oceanography Centre Southampton (NOCS) hosted the AUI programme with ten further institutions collaborating in the project. The project ran from April 2000 until the end of March 2005, with some extensions to projects beyond this date because of research cruise delays. The following cruises were the fieldwork component of the AUI project:

Table 1: Details of the RRS James Clark Ross AUI cruises.

All the cruises utilised the AutoSub autonomous, unmanned and untethered underwater vehicle to collect observations beneath sea-ice and floating ice shelves. AutoSub can be fitted with a range of oceanographic sensors such as:

• Conductivity Temperature Depth (CTD) instruments
• Acoustic Doppler Current Profillers (ADCP)
• A water sampler
• Swath bathymetry systems
• Cameras

In addition to use of AutoSub during each cruise measurements were taken from ship. These varied by cruise but included:

• Ship underway measurements and sampling for parameters such as:
  • Salinity
  • Temperature
  • Fluorescence
  • Oxygen 18 isotope enrichment in water
  • Bathymetry using a swath bathymetry system
• Full-depth CTD casts for with observations of samples taken for parameters such as:
  • Salinity
  • Temperature
  • Fluorescence
  • Optical transmissivity
  • Dissolved oxygen
  • Oxygen 18 isotope enrichment in water
  • Water CFC content
• Sea floor photography and video using the WASP system
• Sea floor sampling with trawls/rock dredges
• Sea ice observations (ASPeCt), drifters and sampling

The AutoSub project also included numerical modelling work undertaken at University College London, UK.

The project included several firsts including the first along-track observations beneath an ice shelf using an autonomous underwater vehicle. The AutoSub vehicle was developed and enhanced throughout this programme and has now become part of the NERC equipment pool for general use by the scientific community. Further information for each cruise can be found in the respective cruise reports (links in Table 1).

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: