Metadata Report for BODC Series Reference Number 1749732
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 |
|||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
Data Identifiers |
|||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
Time Co-ordinates(UT) |
|||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
Spatial Co-ordinates | |||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
Parameters |
|||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
|
Problem Reports
No Problem Report Found in the Database
OSMOSIS Cruise D381 Vessel Mounted ADCP Data Quality Report
The data were visually inspected and found to be noisy. This variability was generally coherent throughout all depth bins, but was particularly apparent in the shallower bins. Obvious spikes were flagged as suspect, but considerable noisiness remains.
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 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
Fugro SeaSTAR 9200-G2 Receiver
The SeaSTAR 9200-G2 is a dual frequency (L1/L2) receiver that incorporates global positioning system (GPS) and global navigation satellite system (GLONASS) reception capability while tracking the Fugro L-Band satellite broadcast of Differential Global Satellite Navigation System (DGSNS) corrections. These corrections can also be received via internet, as a backup.
The SeaSTAR 9200-G2 can be used in conjunction with other services as HP (GPS network solution), XP (GPS or orbit and clock solution) and G2 (Composite GPS/GLONASS orbit and clock solution). These are also dual frequency carrier phase solutions, which allows for a decimeter level accuracy.
The 72 channels received by the SeaSTAR include GPS- L1 C/A code and L1/L2/L2C full cycle carrier, GLONASS- L1/L2 full cycle carrier, Satellite Based Augmentation System (SBAS) and the Fugro L-Band service.
Specifications
Position Accuracy | Horizontal | Vertical |
HP | 10 cm (95%) | 15 cm (95%) |
XP | 15 cm (95%) | 20 cm (95%) |
G2 | 15 cm (95%) | 20 cm (95%) |
Further details can be found in the manufacturer's specification sheet.
Originator's Data Processing
Sample collection
A vessel mounted Ocean Survey 75 kHz ADCP was attached to the RRS Discovery during the second of the two legs of the D381 cruise which was undertaken as part of the Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study (OSMOSIS), funded by NERC.
The ADCP was operational from the ships departure from Falmouth on 14 September 2012 to the study region around the Porcupine Abyssal Plain in the North east Atlantic Ocean; until the ships return to dock on 1 October 2012 .
A hull-mounted Ocean Surveyor broadband 150 kHz ADCP had been operational at the start of the first leg of the D381 cruise which began on 28 August 2012. However part way through the cruise two of the beams stopped reporting velocity. The unit was not able to be repaired on board and was switched off for the entirety of the second leg of the cruise. No data were supplied to BODC for this instrument.
The operational ADCP was mounted in a well 4.15 m forward and 2.5 m to starboard of the 150 kHz well which was 1.75 m to port of the keel, 33 m aft of the bow at the waterline, at an approximate depth of 5.3 m.
Configured by RDI software VmDAS v1.46, the ADCP sampled 96 bins of 8 m lengths over 2 minute intervals using a 30° beam angle. The ADCP was fed with data from the ships GPS, Gyro and ADU systems in order to calculate the true speeds and directions of the currents below the ship.
Data Processing
The ADCP data were processed by RDI software VmDAS v1.46 using routines established during the RRS Discovery cruise D253.
The data were converted into Pstar format, with the velocities scaled to cm/s, the amplitude to 0.45 db, and the time corrected to GPS. An offset of 13 m was applied to the bin depths which equated to the depth of the ADCP below the surface.
The data were then edited according to status flags, where a flag value of 1 indicated bad data. Velocity data where the percentage of pings was greater than 25% when more than one beam had been bad were then replaced with absent data values.
The resulting data were then merged with the navigational files. The velocities were converted to speed and direction so that the heading corrections could be applied before being returned to east and north to apply the misalignment angle and scaling factor.
The time base of the ADCP profile was then shifted to the centre of the 2 minute ensemble.
Field Calibrations
A calibration was achieved using bottom tracking data made available from the departure of the ship from Falmouth.
Using straight, steady speed sections of standard two minute ensemble profiles over reasonably constant bottom depth the following calibrations were derived:
75 kHz | Misalignment angle | Scaling factor |
Mean | 3.5600 | 0.9966 |
SD | 0.5255 | 0.0055 |
References
Allen, J.T. et al. (2013). 'RRS Discovery Cruise 381, 28 Aug - 03 Oct 2012. Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study'. Cruise Report No. 18, National Oceanography Centre, Southampton.
Processing by BODC of RRS Discovery D381 Vessel Mounted ADCP data
The data arrived at BODC in a single Matlab file which contained the processed data collected from the vessel mounted ADCP during the second of the two legs of the D381 cruise, D381B (14 Sept - 1 Oct 2012).
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 | Originator's Units | Description | BODC Parameter Code | BODC Units | Comment |
---|---|---|---|---|---|
adcp.JULD | day number | Julian day | Not transferred | ||
adcp.time | time from 00:00 of the Julian Day | time | Not transferred | ||
adcp.datenum | Number of days from 00:00, 0000 | Matlab date/time | AADYAA01 and AAFDZZ01 | Days and day fraction | Conversion by transfer |
adcp.good3bm | % | Should be percentage return of signal from 3 or more beams, but definition uncertain. | Not transferred | ||
adcp.good4bm | % | Should be percentage return of signal from all 4 beams, but definition uncertain. | Not transferred | ||
adcp.z | m | Depth below sea surface (ADCP bin) | DBINAA01 | m | - |
adcp.vn | cm.s-1 | Northward current velocity (Eulerian) in the water body by shipborne acoustic doppler current profiler (ADCP) | LCNSAS01 | cm.s-1 | - |
adcp.ve | cm.s-1 | Eastward current velocity (Eulerian) in the water body by shipborne acoustic doppler current profiler (ADCP) | LCEWAS01 | cm.s-1 | - |
adcp.lat | Degrees | Latitude north (WGS84) by unspecified GPS system | ALATGP01 | Degrees | - |
adcp.lon | Degrees | Longitude east (WGS84) by unspecified GPS system | ALONGP01 | Degrees | - |
adcp.distrun | Km | Distance travelled | DSRNCV01 | Km | - |
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
Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study (OSMOSIS)
Background
The Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study (OSMOSIS) consortium was funded to deliver NERC's Ocean Surface Boundary Layer (OSBL) programme. Commencing in 2011, this multiple year study will combine traditional observational techniques, such as moorings and CTDs, with the latest autonomous sampling technologies (including ocean gliders), capable of delivering near real-time scientific measurements through the water column.
The OSMOSIS consortium aims to improve understanding of the OSBL, the interface between the atmosphere and the deeper ocean. This layer of the water column is thought to play a pivotal role in global climate and the productivity of our oceans.
OSMOSIS involves collaborations between scientists at various universities (Reading, Oxford, Bangor, Southampton and East Anglia) together with researchers at the National Oceanography Centre (NOC), Scottish Association for Marine Science (SAMS) and Plymouth Marine Laboratory (PML). In addition, there are a number of project partners linked to the consortium.
Scientific Objectives
- The primary goal of the fieldwork component of OSMOSIS is to obtain a year-long time series of the properties of the OSBL and its controlling 3D physical processes. This is achieved with an array of moorings (two nested clusters of 4 moorings, each centred around a central mooring) and gliders deployed near the Porcupine Abyssal Plain (PAP) observatory. Data obtained from this campaign will help with the understanding of these processes and subsequent development of associated parameterisations.
- OSMOSIS will attempt to create parameterisations for the processes which determine the evolving stratification and potential vorticity budgets of the OSBL.
- The overall legacy of OSMOSIS will be to develop new (physically based and observationally supported) parameterisations of processes that deepen and shoal the OSBL, and to implement and evaluate these parameterisations in a state-of-the-art global coupled climate model, facilitating improved weather and climate predictions.
Fieldwork
Three cruises are directly associated with the OSMOSIS consortium. Preliminary exploratory work in the Clyde Sea (September 2011) to hone techniques and strategies, followed by a mooring deployment and recovery cruise in the vicinity of the Porcupine Abyssal Plain (PAP) observatory (in late Summer 2012 and 2013 respectively). Additional opportunist ship time being factored in to support the ambitious glider operations associated with OSMOSIS.
Instrumentation
Types of instrumentation and measurements associated with the OSMOSIS observational campaign:
- Ocean gliders
- Wave rider buoys
- Towed SeaSoar surveys
- Microshear measurements
- Moored current meters, conductivity-temperature sensors and ADCPs
- Traditional shipboard measurements (including CTD, underway, discrete nutrients, LADCP, ADCP).
Contacts
Collaborator | Organisation |
---|---|
Prof. Stephen Belcher | University of Reading, U.K |
Dr. Alberto C Naveira Garabato | University of Southampton, U.K |
Data Activity or Cruise Information
Cruise
Cruise Name | D381B |
Departure Date | 2012-09-14 |
Arrival Date | 2012-10-03 |
Principal Scientist(s) | John T Allen (National Oceanography Centre, Southampton) |
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 |