Metadata Report for BODC Series Reference Number 1765050
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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Time Co-ordinates(UT) |
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Parameters |
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Problem Reports
No Problem Report Found in the Database
RRS Discovery Cruise DY052 Vessel Mounted ADCP Data Quality Report
The data were visually inspected and found to be noisy, particularly in the shallowest 2 bins. Obvious spikes were flagged, but some noisiness remains. Further quality control has been left to the discretion of the end user.
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
RD Instruments- Ocean Surveyor 150kHz Vessel mounted ADCP.
Long-Range Mode | ||
---|---|---|
Vertical Resolution Cell Size3 | Max. Range (m)1 | Precision (cm/s)2 |
4m | 325 - 350 | 30 |
8m | 375 - 400 | 19 |
High-Precision Mode | ||
Vertical Resolution Cell Size3 | Max.Range (m)1 | Precision (cm/s)2 |
4m | 200 - 250 | 12 |
8m | 220 - 275 | 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: 1.5
Bottom Track
Maximum altitude (precision <2cm/s): 600m
Echo Intensity Profile
Dynamic range: 80dB
Precision: ±1.5dB
Transducer & 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 in the manufacturer's website or in the specification sheet.
RRS Discovery DY052 Originator's Vessel Mounted ADCP data processing
Originator's Protocol for Data Acquisition and Analysis
The RRS Discovery DY052 occupied the Extended Ellett Line.
The cruise departed on the 7th June 2016 from the port of Glasgow and returned on the 24th June 2016 to Glasgow.
Sample collection
During cruise DY052, a 75 kHz and a 150 kHz vessel mounted ADCP (VMADCP) Ocean Surveyor was operating. The 75 kHz instrument was configured to 64 bins with intervals of 16 m and the 150 kHz instrument was configured to 64 bins with intervals of 8 m.
The data from the VMADCP was collected in real-time using the RD Instrument VMDas software package which controlled the instrument. The VMDas software allowed data acquisition in a number of configurable formats and performed preliminary screening and transformation of the data from beam to Earth coordinates.
Data Processing
The final processing of the data was done using the CODAS (Common Ocean Data Access System) software provided by the University of Hawaii. CODAS is a suite of Unix and Matlab programs which allows manual inspection and editing of bad profiles and provides best estimates of the required rotation of the data, either from water profiling or bottom tracking.
A summary of these steps are:
- vmadcp_linkcript150 and vmadcp_linkscript76 - creates a new directory called rawdata<<nnn>>and moves the relevant data to this new location.
- adcptree.py dy052<<nnn>> nbenx --datatype enx - sets up a directory tree for the CODAS dataset and an extensive collection of configuration files, text files and m files.
- quick adcp.py --cntfile q py.cnt - loads the data into the directory tree, performs routine editing and processing and makes estimates of both water track and (if available) bottom track calibrations. The raw ping files are also averaged into 5-minute periods. The calibration values are stored in the adcpcal.out and btcaluv.out files found in the cal/watertrk and cal/botmtrk directory respectively and are appended each time quick adcp.py is run.
- Manual editing - data checked in Gautoedit to flag any data that is deemed to be bad.
- quick adcp.py - cntfile q pyedit.cnt - flags from Gautoedit are passed forward and using this command, the discarded data was removed.
- Once the editing and rotations were completed, the final velocities were collated into Mstar files (*.nc) using the Matlab mcod 01 and mcod 02. Files were then appended using mcod_mapend.
Field Calibrations
To provide the best calibration for the velocity data, the mean was taken from BT (bottom track) medians. The final calibration was: rotation angle = 0.2245 °, amplitude = 0.9984 meters.
References
Gary, S.F. et al. (2016). Cruise DY052 Extended Ellett Line. Cruise Report Scottish Association for Marine Science
RRS Discovery DY052 Vessel Mounted ADCP: Processing undertaken by BODC
The data arrived at BODC in two MStar files representing the data collected from the two vessel mounted ADCPs (75 kHz and 150 kHz) during cruise DY052. The data were reformatted to BODC's internal NetCDF format. The following table shows the mapping of variables within the MStar file to appropriate BODC parameter codes:
Originator's Variable | Originator's Units | Description | BODC Parameter Code | BODC Units | Comment |
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bins | dimensionless | Neutral label for the sampling bins of instruments such as ADCP using a convention of monotonic integers starting at 1 for the bin nearest to the instrument. | BINNUMBR | dimensionless | |
uabs | cm.s-1 | Eastward current velocity (Eulerian) in the water body by shipborne acoustic doppler current profiler (ADCP) | LCEWAS01 | cm.s-1 | Eastward values are positive. |
vabs | cm.s-1 | Northward current velocity (Eulerian) in the water body by shipborne acoustic doppler current profiler (ADCP) | LCNSAS01 | cm.s-1 | Northward values are positive. |
uship | m.s-1 | Eastward velocity (over ground) of measurement platform by unspecified GPS system | APEWGP01 | cm.s-1 | Conversion *100 applied. VMADCP navigation data streamed from primary GPS Applanix POS-MV. |
vship | m.s-1 | Northward velocity (over ground) of measurement platform by unspecified GPS system | APNSGP01 | cm.s-1 | Conversion *100 applied. VMADCP navigation data streamed from primary GPS Applanix POS-MV. |
speed | cm.s-1 | Current speed (Eulerian) in the water body by shipborne acoustic doppler current profiler (ADCP) | LCSAAS01 | cm.s-1 | |
shipspd | m.s-1 | Speed (over ground) of measurement platform by unspecified GPS system | APSAGP01 | m.s-1 | VMADCP navigation data streamed from primary GPS Applanix POS-MV. |
depth | metres | Depth below sea surface (ADCP bin) | DBINAA01 | metres | - |
lat | degrees | Latitude north (WGS84) by unspecified GPS system | ALATGP01 | degrees | - |
lon | degrees | Longitude east (WGS84) by unspecified GPS system | ALONGP01 | degrees | 360 subtracted to reference it to Greenwich Meridian. |
The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, missing data by both setting the data to an appropriate value and setting the quality control flag.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
Cruise Name | DY052 |
Departure Date | 2016-06-07 |
Arrival Date | 2016-06-24 |
Principal Scientist(s) | Stefan F Gary (Scottish Association for Marine Science) |
Ship | RRS Discovery |
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 |