Metadata Report for BODC Series Reference Number 668190

• 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

IXSEA PHotonic Inertial Navigation System (PHINS)

The IXSEA PHINS is a all-in-one 3D positioning system which produces high accuracy measurements of position, heading, roll, pitch, depth, velocity and heave. It is designed for use on underwater vehicles such as ROVs.

PHINS uses IXSEA's Fiber Optic Gyroscope technology coupled with an embedded digital signal processor that runs an advanced Kalman filter. It accepts aiding data from a variety of input sources: e.g., global positioning system (GPS), ultra-short baseline (USBL), IXSEA RAMSES Acoustic Synthetic Baseline positioning system, long baseline (LBL), Doppler velocity log (DVL), depth, conductivity-temperature-depth (CTD) and sound velocity probe (SVP) systems. PHINS is suitable for surface or subsea vessels. Its accuracy is variable and depends on the source of the aiding data.

The insturument has 5 inputs, 5 outputs and 1 configuration port, for serial RS232 and 422, and 4 input and 2 output pulse ports. Supported input/output formats are NMEA0183, ASCII and binary.

Specifications

Further details can be found in the manufacturer's specification sheet.

Teledyne RD Instruments Workhorse Navigator Doppler Velocity Log

The Workhorse Navigator (WHN) Doppler Velocity Log (DVL) provides precise velocity and altitude information for a variety of underwater tasks, and can be used in a standalone configuration or integrated with other navigation systems. The DVL incorporates a compass, a tilt meter, a temperature sensor and a 4-beam acoustic transducer as standard, providing bottom and water track velocities, four individual measurements of altitude, heading, tilt and acoustic echo intensity. Pressure, depth and current profiling options are also available.

High resolution data are produced using Broadband signal processing and a four-beam solution gives an independent error velocity measurement as an indicator of data quality. The three standard models are the WHN 300, WHN 600 and WHN 1200, as detailed below. Customised transducers with different frequencies are also available.

Specifications

*Enhanced low-altitude tracking down to 0.25 m is available for the WHN 1200.

Further details can be found in the manufacturer's specification sheet.

BODC Processing

The data were provided to BODC in the form of 5 .bnv matlab files with one file for each mission. The data from the files were transferred to NETCDF format by BODC generated Matlab code. During the transfer the variable sin the originator's files are mapped to unique BODC parameter codes. The paramteter code mapping can be seen in the table below.

Following the transfer the data are screened using BODC developed in-house visualisation software. Suspect data points are marked with the appropriate data qulaity control flag. Absent data are changed to an appropriate value and flagged accordingly.

Originator's Processing

AutoSub is an autonomous underwater vehicle that is desgined to gather data from environments that are unaccessible by other means. AutoSub carries a vast array of instruments that continually log data. This data is supplimented by navigational information. The raw AutoSub navigation file is convreted to a Best navigation file (.bnv) using an AXUM script program.

Navigation is calculated using AutoSub's dead reckoning system along with GPS fixes. All AutoSub systems are synchronised using time so that the data can be merged at a later date if required. A full description of the processing steps performed on the navigation data can be found in the navigation processing document

Multiple AutoSub test missions were undertaken during the cruise before full missions were performed. Unfortunately on the second full mission AutoSub did not return. More information on the deployments can be seen below.

More information on Autosub can be found on page 28 of the cruise report which can be accessed via the JCR97 metadata report.

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: