Metadata Report for BODC Series Reference Number 1021942
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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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.
Originator's Processing
AutoSub was deployed off the coast of Greenland in the Kangerdlugssuaq Fjord area. Floating ice and varying seawater densities in the survey area posed a problem for AutoSub. In order to enable AutoSub to dive below the surface wings were attached. Tests were then performed to ensure the wings worked as required before 5 full missions were performed. A summary of AutoSub deployments can be found below.
Mission | Start date (GMT) | End date (GMT) | Comments |
---|---|---|---|
M369 | 02/09/2004 17:59 | 02/09/2004 18:14 | Test mission for Wings. No data provided to BODC |
M370 | 03/09/2004 06:42 | 03/09/2004 07:10 | Test mission for Wings. No data provided to BODC |
M371 | 03/09/2004 15:00 | 03/09/2004 15:30 | Test mission for Wings. No data provided to BODC |
M372 | 03/09/2004 16:57 | 03/09/2004 20:24 | Test mission for Wings and Homing. No data provided to BODC |
M373 | 04/09/2004 14:40 | 04/09/2004 15:20 | Courtauld Fjord survey. Aborted due to collision with the Seabed. No data provided to BODC |
M374 | 05/09/2004 13:29 | 05/09/2004 15:00 | Courtauld Fjord survey |
M375 | 05/09/2004 16:26 | 05/09/2004 19:11 | Courtauld Fjord survey |
M376 | 08/09/2004 11:55 | 08/09/2004 18:14 | Kangerdlugssuaq Fjord survey |
M375 | 08/09/2004 23:42 | 09/09/2004 06:45 | Kangerdlugssuaq Fjord survey |
More information on the missions undertaken can be found on pages 11 - 14 in the cruise report, which is accessible through the metadata summary report.
ADCP data processing
AutoSub is fitted with two ADCP devices. An RDI 150 kHz downward looking ADCP and an RDI 300 kHz upward looking ADCP. Both ADCPs were set with 8 m profiling bins and data is recorded at 2 second intervals. AutoSub itself records data only every 2.6 seconds, so there are regular spaced data cycles that contain no data. The final processed ADCP data file was named m###ls2_proc3.mat where ### represents the mission number. The processed files also contained data binned to 100 m horizontally and with the upward and downward looking ADCP data combined together into one variable.
BODC Processing
The data were provided to BODC in 5 Matlab files. Data for both the upward and downward looking ADCPs were in the same file. Each file contained multiple versions of the data. One variable had the data binned to 100 m horizontally and one variable had combined the upward and downward looking ADCP data. It was decided that downward and upward ADCP ADCP data would be transferred separately and the combined variable would not be used. This was to make the final NETCDF files easier to understand and interpret. The raw 2 second bin data is transferred and not the horizontally binned data.
The data were transferred to NETCDF format using BODC generated Matlab code. Two NETCDF files were produced for each mission, one for the upward looking ADCP and one for the downward looking ADCP. The transfer involves mapping the originator's variables to unique BODC parameter codes. The parameter mapping can be seen below. Note that some codes are the same for two different variables. The variables are the same parameter and are from the different ADCPs so the codes can be the same as they are not in the same NETCDF file.
BODC Parameter Code Mapping
Originator's variable | Description | Units | BODC Parameter Code | Units | Comments |
---|---|---|---|---|---|
Pos_E | Longitude | Degrees | ALONGP01 | Degrees | - |
Pos_N | Latitude | Degrees | ALATGP01 | Degrees | - |
Travelled_km | Distance traveled by AutoSub | km | DSRNCV01 | km | - |
dist100 | Distance traveled by AutoSub binned to 100 m horizontally | km | - | - | Not transferred. Horizontally binnned data has not been transferred. |
bindepthdn | Depth of downward looking bins | Metres | DBINAA01 | Metres | - |
bindepthmap | Depth of ADCP bins | Metres | - | - | Not transferred. Variable is a combination of upward and downward data. |
bindepthup | Depth of upward looking bins | Metres | DBINAA01 | Metres | - |
dep | Depth of AutoSub | Metres | ADEPZZ01 | Metres | - |
dep100 | Depth of AutoSub binned to 100 m horizontally | Metres | - | - | Not transferred. Horizontally binnned data has not been transferred. |
intensdn1 | Acoustic backscatter from downward ADCP | dB | ACBSADCP | dB | - |
intensmap | Acoustic backscatter from ADCP | dB | - | - | Not transferred. Variable is a combination of upward and downward data. |
intensup1 | Acoustic backscatter from upward ADCP | dB | ACBSADCP | dB | - |
sdraft | Surface draft | Metres | ASLVMWHA | Metres | Only recorded from upward looking ADCP so not transferred. |
sdraft100 | Surface draft binned to 100 m horizontally | Metres | - | - | Not transferred. Horizontally binnned data has not been transferred. |
vdowndnreal | Downward current velocity from downward ADCP | mm s-1 | LCSAAS01 | cm s-1 | Values divided by 10 to convert units. |
vdownmap | Downward/upward current velocity from ADCP | mm s-1 | - | - | Not transferred. Variable is a combination of upward and downward data. |
vdownupreal | Upward current velocity from upward ADCP | mm s-1 | LCSAAS01 | cm s-1 | Values divided by 10 to convert units. |
veastdnreal | Eastward current velocity from downward ADCP | mm s-1 | LCEWAS01 | cm s-1 | Values divided by 10 to convert units. |
veastmap | Eastward current velocity from ADCP | mm s-1 | - | - | Not transferred. Variable is a combination of upward and downward data. |
veastupreal | Eastward current velocity from upward ADCP | mm s-1 | LCEWAS01 | cm s-1 | Values divided by 10 to convert units. |
vnorthdnreal | Northward current velocity from downward ADCP | mm s-1 | LCNSAS01 | cm s-1 | Values divided by 10 to convert units. |
vnorthmap | Northward current speed from ADCP | mm s-1 | - | - | Not transferred. Variable is a combination of upward and downward data. |
vnorthupreal | Northward current velocity from upward ADCP | mm s-1 | LCNSAS01 | cm s-1 | Values divided by 10 to convert units. |
verrdnreal | Current velocity error from downward ADCP | mm s-1 | LERRAS01 | cm s-1 | Values divided by 10 to convert units. |
verrmap | Current velocity error from ADCP | mm s-1 | - | - | Not transferred. Variable is a combination of upward and downward data. |
verrupreal | Current velocity error from upward ADCP | mm s-1 | LERRAS01 | cm s-1 | Values divided by 10 to convert units. |
w100 | Water depth binned to 100 m horizontally | Metres | - | - | Not transferred. Horizontally binnned data has not been transferred. |
wdepth | Water depth | Metres | MBANUV01 | Metres | - |
The data were then screened using BODC in-house visualisation software. Suspect data points are flagged with the appropriate data quality control flag.
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.
Cruise No. | Cruise No. synonyms | Dates | Areas of study |
---|---|---|---|
JR20030218 | JR84 | 28 February 2003 to 4 April 2003 | Amundsen Sea, Antarctica |
JR20040813 | JR106, JR106a, JR106N (North) | 10 August 2004 to 30 August 2004 | Northeast Greenland Continental Shelf, Greenland |
JR20040830 | JR106b, JR106S (South) | 30 August 2004 to 16 September 2004 | Kangerlussuaq Fjord, Greenland |
JR20050203 | JR97, JR097 | 3 February 2005 to 11 March 2005 | Fimbul Ice Shelf and Weddell Sea, Antarctica . This cruise was redirected from the Filcner-Ronne Ice Shelf to the Fimbul Ice Shelf because of unfavourable sea-ice conditions. |
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
Cruise Name | JR20040830 (JR106B) |
Departure Date | 2004-08-30 |
Arrival Date | 2004-09-16 |
Principal Scientist(s) | Julian A Dowdeswell (University of Cambridge, Scott Polar Research Institute) |
Ship | RRS James Clark Ross |
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 |