Metadata Report for BODC Series Reference Number 1204399
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
Data Description |
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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
Instrument Description
A 75 kHz Teledyne RD Instruments Ocean Surveyor (OS75) vessel mounted ADCP was installed on the port drop keel of the James Cook, aligned with the bottom of the hull. The draft of the ship is 6.9 m and when lowered the keel extends 2.8 m below the hull. The resulting transceiver depths are 6.9 m when the keel is retracted and 9.7 m when the keel is lowered.
RD Instruments- Ocean Surveyor 75kHz Vessel mounted ADCP.
| Long-Range Mode | ||
|---|---|---|
| Vertical Resolution Cell Size3 | Max. Range (m)1 | Precision (cm/s)2 |
| 8m | 520 - 650 | 30 |
| 16m | 560 - 700 | 17 |
| High-Precision Mode | ||
| Vertical Resolution Cell Size3 | Max. Range (m)1 | Precision (cm/s)2 |
| 8m | 310 - 430 | 12 |
| 16m | 350 - 450 | 9 |
1 Ranges at 1 to 5 knots ship speed are typical and vary with situation.
2 Single-ping standard deviation.
3 User's choice of depth cell size is not limited to the typical values specified.
Profile Parameters
- Velocity long-term accuracy (typical): ±1.0%, ±0.5cm/s
- Velocity range: -5 to 9m/s
- # of depth cells: 1 - 128
- Max ping rate: 0.7
Bottom Track
Maximum altitude (precision <2cm/s): 950m
Echo Intensity Profile
Dynamic range: 80dB
Precision: ±1.5dB
Transducer and Hardware
Beam angle: 30°
Configuration: 4-beam phased array
Communications: RS-232 or RS-422 hex-ASCII or binary output at 1200 - 115,200 baud
Output power: 1000W
Standard Sensors
Temperature (mounted on transducer)
- Range: -5° to 45°C
- Precision: ±0.1°C
- Resolution: 0.03°
Environmental
Operating temperature: -5° to 40°C (-5° to 45°C)*
Storage temperature: -30° to 50°C (-30° to 60°C)*
*later instruments have greater range.
Web Page
Further details can be found on the manufacturer's website or in the specification sheet
Trimble Applanix Position and Orientation Systems for Marine Vessels (POSMV)
The Position and Orientation Systems for Marine Vessels (POSMV) is a real time kinematic (RTK) and differential global positioning system (DGPS) receiver for marine navigation. It includes an inertial system that provides platform attitude information. The instrument provides accurate location, heading, velocity, attitude, heave, acceleration and angular rate measurements.
There are three models of Applanix POSMV, the POS MV 320, POS MV Elite and the POS MV WaveMaster. POS MV 320 and POS MV WaveMaster are designed for use with multibeam sonar systems, enabling adherence to IHO (International Hydrographic Survey) standards on sonar swath widths of greater than ± 75 degrees under all dynamic conditions. The POS MV Elite offers true heading accuracy without the need for dual GPS installation and has the highest degree of accuracy in motion measurement for marine applications.
Specifications
POS MV 320
| Componenet | DGPS | RTK | GPS Outage |
|---|---|---|---|
| Position | 0.5 - 2 m 1 | 0.02 - 0.10 m 1 | <2.5 m for 30 seconds outages, <6 m for 60 seconds outages |
| Roll and Pitch | 0.020° | 0.010° | 0.020° |
| True Heading | 0.020° with 2 m baseline 0.010° with 4 m baseline | - | Drift <1° per hour (negligible for outages <60 seconds) |
| Heave | 5 cm or 5% 2 | 5 cm or 5% 2 | 5 cm or 5% 2 |
POS MV WaveMaster
| Accuracy | DGPS | RTK | GPS Outage |
|---|---|---|---|
| Position | 0.5 - 2 m 1 | 0.02 - 0.10 m 1 | <3 m for 30 seconds outages, <10 m for 60 seconds outages |
| Roll and Pitch | 0.030° | 0.020° | 0.040° |
| True Heading | 0.030° with 2 m baseline | - | Drift <2° per hour |
| Heave | 5 cm or 5% 2 | 5 cm or 5% 2 | 5 cm or 5% 2 |
POS MV Elite
| Accuracy | DGPS | RTK | GPS Outage |
|---|---|---|---|
| Position | 0.5 - 2 m 1 | 0.02 - 0.10 m 1 | <1.5 m for 60 seconds outages DGPS, <0.5 m for 60 seconds outage RTK |
| Roll and Pitch | 0.005° | 0.005° | 0.005° |
| True Heading | 0.025° | 0.025° | Drift <0.1° per hour (negligible for outages <60 seconds) |
| Heave | 3.5 cm or 3.5% 2 | 3.5 cm or 3.5% 2 | 3.5 cm or 3.5% 2 |
1 One Sigma, depending on quality of differential corrections
2 Whichever is greater, for periods of 20 seconds or less
Further details can be found in the manufacturer's specification sheet.
JC088 75 kHz VMADCP Originator Processing
The following information is an adapted summary of the JC088 cruise report on the vessel-mounted ADCP (VMADCP).
Configuration and acquisition
Positional and attitude information were provided via a Position and Orientation Systems for Marine Vessels (POSMV) multi-receiver GPS attitude sensor. The RDI proprietary software VMDAS was used to configure the ADCP and perform velocity mapping to the reference frame of the vessel. Bottom tracking was enabled where possible. A suite of MATLAB routines were used to perform data screening and transformation to absolute velocities in Earth coordinates. A summary of the configuration and processing steps is given below.
OS75 VMADCP Configuration:
- Bin configuration:
- Bin size = 16 m and no. of bins = 48 for:
- ADCP75_JC08800x_000000_12_abs.mat
- ADCP75_JC08800x_000000_31_abs.mat
- ADCP75_JC08800x_000000_32_abs.mat
- Bin size = 8 m and no. of bins = 96 for:
- ADCP75_JC08800x_000000_14_abs.mat (Note: this setup resulted in more noise in the data)
- Bin size = 16 m and no. of bins = 48 for:
- Blank after transmit =
- 16 m for:
- ADCP75_JC08800x_000000_12_abs.mat
- 8 m for:
- ADCP75_JC08800x_000000_14_abs.mat
- ADCP75_JC08800x_000000_31_abs.mat
- ADCP75_JC08800x_000000_32_abs.mat
- 16 m for:
- Transducer depth = 6 m
- Bottom track (when on) maximum depth 1200 m
- Time between pings = as fast as possible (typically 5s)
- Low-resolution long-range processing mode
Summary of Matlab processing steps
The RDI binary file with extension ENX (single-ping ADCP ship referenced data from VMDAS) and extension N1R (ascii NMEA output from POSMV saved by VMDAS) were read into the MATLAB environment. Ensembles with no ADCP data were removed and ensembles with bad or missing POSMV GPS heading data were identified and the substituted for the ship's GYRO heading.
The attitude information was time-merged with single ping data and the heading data was used to rotate single ping ADCP velocities from the vessel centreline reference to the True North reference. The transducer misalignment error was corrected for (derived from the misalignment determination - see 'Calibration' below).
The ship's velocity was derived from POSMV positional information.
Further data screening was performed:
- Max heading change between pings (10 degrees per ping) excluded
- Max ship velocity change between pings (>2ms-1 pingrate-1) excluded
- Error velocity greater than double the standard deviation of error velocities of the single ping profile excluded
- All data averaged into 120-second super-ensembles (user selectable)
- Absolute water velocities were determined from either bottom track derived ship velocity or POSMV GPS derived ship velocity, dependent on depth
Calibration
JC088 operated both on and off the continental shelf so bottom tracking was possible on some program runs. Alignment and amplitude corrections were calculated from data for the whole cruise period, excluding the steam through the Irish Sea, but were applied to the whole cruise period including the steam through the Irish Sea. They were as follows:
- Misalignment = -3.2881o
- Amplitude = 0.996432
JC088 75 kHz VMADCP Processing by BODC
The data to be banked by BODC were received as 4 MATLAB files as follows:
- ADCP75_JC8800x_000000_12_abs.mat; series 12; 16:35 on 28/06/2013 - 07:20 on 29/06/2013 (steam from North Passage to Malin shelf edge).
- ADCP75_JC8800x_000000_14_abs.mat: series 13,14; 7:22 on 29/06/2013 - 11:50 on 30/06/2013 (short period using bin size = 8 m).
- ADCP75_JC8800x_000000_31_abs.mat; series 15 - 31; 11:50 on 30/06/2013 - 12:09 on 22/07/2013 (main body of cruise, ending on steam south, roughly parallel to Anglesey).
- ADCP75_JC8800x_000000_32_abs.mat; series 32; 12:09 on 22/07/2013 - 12:30 on 23/07/2013 (steam between Irish Sea and English Channel).
The file number corresponds to the highest series number contained therein. Whilst the *_abs.mat files should be sufficient for most purposes, BODC has archived all of the originators source and intermediate files which are available upon request.
Parameter Code Mapping
The received files were reformatted to BODC's internal file format which is a NetCDF subset. Due to the large size of file *31_abs.mat, it was split into two separate files with the split occurring at midnight on the 9th/10th July.
The following table shows how the variables within the *.mat files were mapped to appropriate BODC parameter codes:
| Originator's Identifier | Originator's Units | Description | BODC Parameter | BODC Units | Comments |
| OS75_abs.nav.txy2(1,:) | Day of the year | Day of the year and day fraction | AADYAA01 | Days | - |
| AAFDZZ01 | Days | Time elapsed between 00:00 UT on the corresponding date | |||
| OS75_abs.nav.txy2(2,:) | o | Longitude east | ALONGP01 | o | - |
| OS75_abs.nav.txy2( 3,:) | o | Latitude north | ALATGP01 | o | - |
| OS75_ave_ping.ship_velocity(1,:) | m s-1 | Eastward velocity of the ship | APEWGP01 | cm s-1 | - |
| OS75_ave_ping.ship_velocity(2,:) | m s-1 | Northward velocity of the ship | APNSGP01 | cm s-1 | - |
| OS75_ave_ping.heading | o | Ship's heading | APDAGP01 | o | - |
| N/A | N/A | Monotonically increasing bin number, with 1 being closest to the ADCP | BINNUMBER | dimensionless | Auto-generated by transfer |
| OS75_abs.depth | m | Depth below sea surface (ADCP bin) | DBINAA01 | m | - |
| OS75_abs.vel(:,1,:) | m s-1 | Eastward current velocity (Eulerian) in the water column by VMADCP | LCEWAS01 | cm s-1 | - |
| OS75_abs.vel(:,2,:) | m s-1 | Northward current velocity (Eulerian) in the water column by VMADCP | LCNSAS01 | cm s-1 | - |
| OS75_ave_ping.vel(:,1,:) | m s-1 | Eastward current velocity (relative to moving platform) in the water body by VMADCP | LREWAS01 | cm s-1 | - |
| OS75_ ave_ping.vel(:,2,:) | m s-1 | Northward current velocity (relative to moving platform) in the water body by VMADCP | LRNSAS01 | cm s-1 | - |
| OS75_ ave_ping.vel(:,3,:) | m s-1 | Upward current velocity in the water body by VMADCP | LRZAAS01 | cm s-1 | - |
| OS75_ ave_ping.err_vel | m s-1 | Current velocity error in the water body by VMADCP | LERRAS01 | cm s-1 | - |
| OS75_ ave_ping.amp | dB | Signal return amplitude from the water body by VMADCP | ASAMAS01 | dB | - |
| OS75_ ave_ping.pg | % | Acceptable proportion of signal returns by VMADCP | PCGDAP01 | % | - |
The following variables were not included in the transferred data:
| OS75_abs.nav.txy1 | ship's position from the first fix after the previous ADCP ping |
| OS75_abs.ref | reference velocity layer, not required |
| OS75_ave_ping.nav.txy1 | ship's position from the first fix after the previous ADCP ping |
| OS75_ave_ping.nav | same as OS75_abs.nav |
| OS75_ave_ping.att | ship's attitude data, not required |
| OS75_ave_ping.ref | reference velocity layer, not required |
| OS75_ave_ping.bt | bottom track data, not required |
| OS75_ave_ping.depth | 2D bin depths, not required |
| bindepth | duplication of OS75_abs.depth |
Screening
No quality control flags were provided by the originator. The reformatted data were visualised using the in-house EDSERPLO software. It was not necessary for BODC to apply any quality control flags to this data.
In all the files some data cycles were entirely blank including the time and position channels, and these have been deleted. No other data were edited or deleted.
The cruise report noted that rough weather caused the frequent presence of air bubbles under the hull, with profiles being quite poor around 30/06/2013 and again on 04/07/2013.
Banking
Once quality control screening was complete, the data were archived in the BODC National Oceanographic Database and the associated metadata were loaded into an ORACLE Relational Database Management System.
Project Information
Fluxes Across Sloping Topography of the North East Atlantic (FASTNEt)
Background
The FASTNEt consortium was funded to deliver NERC's Ocean Shelf Edge Exchange Programme. Commencing in October 2011, this four year study aims to couple established observational techniques, such as moorings and CTDs, with the very latest in autonomous sampling initiatives - including use of Autosub Long Range and gliders. With the aid of novel model techniques, these observations will be utilised to construct a new paradigm of Ocean/Shelf exchange.
Shelf edge regions mark the gateway between the world's deep oceans and shallower coastal seas, linking terrestrial, atmospheric and oceanic carbon pools and influencing biogeochemical fluxes. Shelf edge processes can influence near-shore productivity (and fisheries) and ultimately affect global climate.
FASTNEt brings together researchers from multiple UK organisations. Further collaboration has been established with five Project Partners: the UK Met Office, Marine Scotland Science, Agri-Food and Biosciences Institute, Marine Institute Ireland and Scripps Institution of Oceanography.
Scientific Objectives
- To determine the seasonality of physical gradients and exchange across the shelf edge by deploying new observational technologies (gliders, Autosub Long Range) and established techniques (long term moorings, drifters)
- To quantify key exchange mechanisms and to collect new data targeted at testing and improving high resolution models of the shelf edge, by carrying out detailed process studies in contrasting regions of the shelf edge of the NE Atlantic margin
- To develop a new parameterisation of shelf edge exchange processes suitable for regional-scale models, using improved resolution numerical, and new empirical models constrained by the observations
- To test the new parameterisations in a regional model in the context of making an assessment of inter-annual variability of ocean-shelf exchange.
Fieldwork
Three survey sites on the UK shelf edge have been selected for FASTNEt. These are a) the Celtic Sea shelf edge, b) Malin shelf and c) North Scotland shelf. Fieldwork is centred around two research cruises. The first, to the Celtic Sea, on RRS Discovery in June 2012. The second cruise visits the Malin shelf on RRS James Cook, during summer 2013. In addition to these dedicated cruises, opportunist cruise activity to the North Scotland shelf has been agreed with project partner Marine Scotland Science. Autonomous technologies will complement observations made during the cruises and provide knowledge of seasonal and inter-annual variability in exchange processes.
Instrumentation
Types of instruments/measurements:
- Gliders
- Autosub Long Range
- Drifter buoys
- Scanfish
- Microstructure profilers
- Moored CTD/CT loggers and ADCPs
- Shipboard measurements: CTD, underway, nutrients (and other discrete sampling), LADCP, ADCP.
Contacts
| Collaborator | Organisation |
|---|---|
| Prof. Mark Inall (lead) | Scottish Association for Marine Science, U.K |
| Dr. Jason Holt | National Oceanography Centre, U.K |
| Dr. Peter Miller | Plymouth Marine Laboratory, U.K |
| Dr. Mattias Green | Bangor University, U.K |
| Prof. Jonathan Sharples | University of Liverpool, U.K |
| Dr. Vasyl Vlasenko | University of Plymouth, U.K |
Data Activity or Cruise Information
Cruise
| Cruise Name | JC088 |
| Departure Date | 2013-06-28 |
| Arrival Date | 2013-07-24 |
| Principal Scientist(s) | Mark E Inall (Scottish Association for Marine Science) |
| Ship | RRS James Cook |
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 |
