Metadata Report for BODC Series Reference Number 1763516
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
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Time Co-ordinates(UT) |
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Parameters |
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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
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
| WHN 300 | WHN 600 | WHN 1200 | |
|---|---|---|---|
| Transducer frequency (kHz) | 300 | 600 | 1200 |
| Depth rating (m) | 3000 or 6000 | 3000 or 6000 | 3000 or 6000 |
| Temperature range (deg C) | -5 to 45 | -5 to 45 | -5 to 45 |
| Compass accuracy (deg) | ±2 at 60 deg dip, 0.5g | ±2 at 60 deg dip, 0.5g | ±2 at 60 deg dip, 0.5g |
| Tilt accuracy (deg) | ±0.5, up to ±15 | ±0.5, up to ±15 | ±0.5, up to ±15 |
| Pressure and depth | optional | optional | optional |
| Current profiling | optional | optional | optional |
| Velocity range (m s-1) | ±10 | ±10 | ±10 |
| Velocity resolution (cm s-1) | 0.1 | 0.1 | 0.1 |
| Maximum ping rate (Hz) | 7 | 7 | 7 |
| Bottom velocity | |||
| Minimum altitude (m) | 1.0 | 0.7 | 0.5* |
| Maximum altitude (m) | 200 | 90 | 30 |
| Accuracy (cm s-1) | ±0.4% ±0.2 | ±0.2% ±0.1 | ±0.2% ±0.1 |
| Water reference velocity | |||
| Minimum range (m) | 1.0 | 0.7 | 0.25 |
| Maximum range (m) | 110 | 50 | 18 |
| Layer size | selectable | selectable | selectable |
| Accuracy (cm s-1) | ±0.4% ±0.2 | ±0.3% ±0.2 | ±0.2% ±0.1 |
*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 - Autosub data
Data were received by BODC in Matlab files, with one file containing all data from the Autosub missions. The data were reformatted to QXF (a NetCDF file format) by in house software. A separate QXF file was created for data from each data type from each mission. Metadata were also extracted from the originator's file and used to populate the BODC database.
The following tables shows how the variables within the files were mapped to appropriate BODC parameter codes for each of the data types supplied:
CTD data
| Originator's parameter name | Origintator's units | Description | BODC Parameter Code | BODC Units | Comments |
|---|---|---|---|---|---|
| Pasub | Decibars | Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level | PRESPR01 | Dbars | |
| Depthasub | Metres | Depth below surface of the water body by profiling pressure sensor and converted to seawater depth using UNESCO algorithm | DEPHPR01 | Metres | |
| DOasub | Millilitres per litre | Concentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by in-situ sensor | DOXYZZ01 | Micromoles per litre | Conversion of *44.66 applied. |
| Latasub | Degrees north | Latitude north | ALATZZ01 | Degrees north | |
| Lonasub | Degrees east | Longitude east | ALONZZ01 | Degrees east | |
| Sasub | PSU | Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm | PSALST01 | Dimensionless | |
| Tasub | Degrees Celsius | Temperature of the water body | TEMPPR01 | Degrees Celsius | |
| Traasub | Percent | Transmittance (unspecified wavelength) per unspecified length of the water body by transmissometer. | POPTZZ01 | Percent | |
| - | - | Potential temperature of the water body by computation using UNESCO 1983 algorithm | POTMCV01 | Degrees Celsius | Derived by BODC where source variables are available |
| - | - | Sigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm | SIGTPR01 | Kilograms per cubic metre | Derived by BODC where source variables are available |
| - | - | Saturation of oxygen {O2 CAS 7782-44-7} in the water body [dissolved plus reactive particulate phase] | OXYSZZ01 | Percent | Derived by BODC where source variables are available |
Ice draft data
| Originator's parameter name | Origintator's units | Description | BODC Parameter Code | BODC Units | Comments |
|---|---|---|---|---|---|
| Lat_Icedraft | Degrees north | Latitude north | ALATZZ01 | Degrees north | |
| Lon_Icedraft | Degrees east | Longitude east | ALONZZ01 | Degrees east | |
| IceDraft | Metres | Ice draft on the water body by acoustic doppler current profiler (ADCP) | ARDECI01 | Metres |
Seabed depth data
| Originator's parameter name | Origintator's units | Description | BODC Parameter Code | BODC Units | Comments |
|---|---|---|---|---|---|
| Lat_SeabedDepth | Degrees north | Latitude north | ALATZZ01 | Degrees north | |
| Lon_SeabedDepth | Degrees east | Longitude east | ALONZZ01 | Degrees east | |
| SeabedDepth | Metres | Sea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body | MBANZZZZ | Metres |
Quality control
Following transfer to QXF, the data were quality controlled using BODC's in-house visualisation software.
Originator's processing - Autosub data
Data collection
Autosub missions were completed during Nathaniel B Palmer cruise NBP09-01 (January 2009) in the Amundsen Sea near the Pine Island Glacier. The data were collected for the Natural Envrironment Research Council funded Ocean Circulation and Ice Shelf Melting on the Amundsen Sea Continental Shelf project (NE/G001367/1).The Autosub was equipped with the following instrumentation: Seabird 9+ CTD, with dual conductivity and temperature sensors plus a SBE43 dissolved oxygen sensor and Wetlabs transmissometer; Simrad EM2000 multi-beam echosounder; upward-looking RDI 300 kHz ADCP; downwardlooking RDI 150 kHz ADCP.
For more information about the Autosub missions and data collection see the cruise report
Data processing
The data collected were processed by the originator and the CTD data plus geometry data (ice draft and sea bed depth) from the ADCP ranges were supplied to BODC.
For information about the Autosub data processing see the cruise report
Project Information
Ocean Circulation and Ice Shelf Melting on the Amundsen Sea Continental Shelf
Background and objectives
The Ocean Circulation and Ice Shelf Melting on the Amundsen Sea Continental Shelf is a NERC funded project designed to understand what is happening to the Antarctic Ice Sheet. The Pine Island Glacier is the main focus of this project and it represents one of the ice sheets where the fastest changes are happening. Despite seeing the signs of these changes, scientists have yet to uncover what is causing them.
Data collection techniques involve the use of a robotic submarine capable of navigating beneath the ice, make measurements along a pre-defined track and return to the surface where data transmission/retrieval occurs. Data collected from these missions will be used to build a computer model that describes the flow of water within the remote cavern beneath glacier and in the sea to the north of it. Using this model we will determine if there have been any changes in the water temperature in Pine Island Bay over the past 20 years and how such changes would have affected melting of the glacier base. The results can then be used by other scientists to establish if changes in the glacier's melt rate could have caused the ice sheet to thin in the way that has been observed, and there will be a greater certainty when stating what impact the glaciers of Pine Island Bay will have on the future coastlines of Holland and East Anglia.
Participants
This project is coordinated by the British Antarctic Survey (BAS) on behalf of NERC and carried out in collaboration with American scientists (funded by the National Science Foundation). Data collection activities took place on board the Nathaniel B. Plamer, operated by the Antarctic Support Contract on a long-term charter from Edison Chouest Offshore, but with isntrumentation owned by BAS.
Fieldwork and data collection
Deployment of an Autosub3 AUV allowed for data collection within a pre-programmed track while navigating by dead reckoning relative to the seabed or the ice-shelf base.
Data management
Data management for the autosub data will be done by the British Oceanographic Data Centre whilst other ice data will be managed by the Polar Data Centre.
Data Activity or Cruise Information
Cruise
| Cruise Name | NBP0901 (DynaLiFe, GPpr03) |
| Departure Date | 2009-01-05 |
| Arrival Date | 2009-02-28 |
| Principal Scientist(s) | Adrian Jenkins (British Antarctic Survey), Hein J de Baar (Royal Netherlands Institute for Sea Research) |
| Ship | RV Nathaniel B. Palmer |
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:
| Flag | Description |
|---|---|
| Blank | Unqualified |
| < | Below detection limit |
| > | In excess of quoted value |
| A | Taxonomic flag for affinis (aff.) |
| B | Beginning of CTD Down/Up Cast |
| C | Taxonomic flag for confer (cf.) |
| D | Thermometric depth |
| E | End of CTD Down/Up Cast |
| G | Non-taxonomic biological characteristic uncertainty |
| H | Extrapolated value |
| I | Taxonomic flag for single species (sp.) |
| K | Improbable value - unknown quality control source |
| L | Improbable value - originator's quality control |
| M | Improbable value - BODC quality control |
| N | Null value |
| O | Improbable value - user quality control |
| P | Trace/calm |
| Q | Indeterminate |
| R | Replacement value |
| S | Estimated value |
| T | Interpolated value |
| U | Uncalibrated |
| W | Control value |
| X | Excessive difference |
SeaDataNet Quality Control Flags
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
| Flag | Description |
|---|---|
| 0 | no quality control |
| 1 | good value |
| 2 | probably good value |
| 3 | probably bad value |
| 4 | bad value |
| 5 | changed value |
| 6 | value below detection |
| 7 | value in excess |
| 8 | interpolated value |
| 9 | missing value |
| A | value phenomenon uncertain |
| B | nominal value |
| Q | value below limit of quantification |
