Metadata Report for BODC Series Reference Number 1766194
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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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
RRS Discovery DY052 LADCP instrument description
LADCP deployments were carried out using the instrumentation detailed below.
The ADCP were attached to a SeaBird 9plus CTD frame during each deployment.
Instrument | Serial # | CTD casts |
---|---|---|
TRDI WHM 300kHz Workhorse ADCP | 4275 | 1-50 |
TRDI WHM 300kHz Workhorse ADCP | 13400 | 51-73 |
TRDI WHM 300kHz Workhorse ADCP | 13399 | 74-89 |
Teledyne RDI's Workhorse Monitor ADCP
The Workhorse Monitor acoustic doppler current profler (Teledyne RD Instruments) is a long-range and long-term self contained ADCP. It has a patented four beam signal (300, 600 or 1200 kHz) and a standard depth rating of 200m or 600m. It operates effectively between temperatures of -5°C and 45°C and has a velocity accuracy of ±1% ±5mm/s.
RRS Discovery DY052 LADCP: Processing undertaken by BODC
The data arrived at BODC in 89 Matlab files. The files contained u, v and z data collected from 89 LADCP deployments undertaken throughout the DY052 cruise. The data were reformatted to BODC's internal NetCDF format and the following table shows the mapping of variables within the .mat file to the appropriate BODC parameter codes:
Originator's Variable | Units | Description | BODC Parameter Code | Units | Comment |
---|---|---|---|---|---|
u(eastward velocity) | m/s | Eastward current velocity (Eulerian) in the water body by lowered acoustic doppler current profiler (ADCP)) | LCEWLW01 | cm/s | Units converted from m/s to cm/s by multiplying by 100 |
v (northward velocity) | m/s | Northward current velocity (Eulerian) in the water body by lowered acoustic doppler current profiler (ADCP) | LCNSLW01 | cm/s | Units converted from m/s to cm/s by multiplying by 100 |
z(depth) | m | Depth below surface of the water body | ADEPZZ01 | m | - |
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.
RRS Discovery DY052 Originator's LADCP data processing
Sampling Strategy
Lowered Acoustic Doppler Current Profiler (LADCP) data were gathered during the RRS Discovery DY052 cruise which occupied the Extended Ellett Line.
Data Processing
The data collected by the instrument were downloaded after each cast and stored as RDI binary files. The data were then processed following the cruise using the IX.8 version of software provided Lamont- Doherty Earth Observatory (LDEO) which calculates velocities using an inverse method.
Please refer to Thurnherr (2014) and cruise report for a more detailed processing methodology. However, please be aware that this processing guide is for software versions IX.7 to IX.10 only, and changes have been made between versions which have the potential for significantly changing the solutions.
More detailed processing was then undertaken by the originator during the cruise using Matlab scripts. The processing steps are listed below:
- processing without any auxiliary data
- merging with CTD and GPS data
- processing with constraint from VMADCP data (except for casts 1, 61, 62, 66 and 70-72 which had insufficient VMADCP data to create a constraint)
- visual inspection to compare with VMADCP data (top of the profile)
- checking that bottom-tracking velocities match those of the water track
- checking the performance of the 4 beams
- comparing profiles from the up and down casts to check that they are both complete
- synchronisation of the real-time clock of the LADCP with the ship's GPS clock if it was more than a few seconds in error
The raw RDI binary files and the ASCII data files created before Matlab processing began are available on request from BODC.
References
Thurnherr, A.M., (2014). How to Process LADCP Data with the LDEO Software (versions IX.7 - IX.10).
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 |