Metadata Report for BODC Series Reference Number 1193197
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
These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.
If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:
"Contains public sector information licensed under the Open Government Licence v1.0."
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.
RAPID cruise JC063/JC064 150kHz Shipboard ADCP data processing
Originator's processing
The following was taken from the JC064 cruise report. For more detailed information please refer to Cunningham (2011).
The 150kHz Ocean Surveyor ADCP is situated on the port drop keel of RRS James Cook. Data are acquired using the RD Instruments VmDas software package version 1.42. The ship's POSMV data stream was used as the accurate source of heading and position.
ADCP setup
Variable | Setting |
---|---|
Number of Bins | 96 |
Bin size | 4m |
Blank distance | 4m |
Transducer depth | 6m |
Processing mode | Low resolution long range |
Maximum range | 400m |
Speed of sound considerations
In order to calculate water velocities, VMADCPs require an estimated value of sound speed. Temperature has the largest effect on sound speed; a change of 1°C in temperature affects up to 3 times more than a psu change of one unit. Sound speed only needs to be considered at transducer depth (Cunningham, 2011). The temperature needs to be compared to the measured remote temperature (tsg) and if the difference is over 1°C, corrections might be considered. Throughout this cruise, salinity was set at 35psu and the difference between the temperature at the transducer depth and the tsg was always less than 1°C. Thus no calibrations for sound speed were made.
Post-processing
The final processing of data was done using the CODAS (Common Ocean Data Access System) suite of software provided by the University of Hawaii. This suite of Python and Matlab programs allows manual inspection and removal of bad profiles and provides best estimates of the required rotation of the data, either from water profiling or bottom tracking. During this cruise, a new Matlab script enclosing all post processing steps was written, making the processing easier and faster.
Calibration
In order to obtain accurate horizontal velocities, it is vital to correct for heading errors. The navigation on the RRS James Cook is fed directly into VmDas from the Applanix POSMV, which incorporates a GPS heading source that is not sensitive to many of the heading errors that occur when gyrocompassses are used in isolation. Best calibration estimates are obtained when the velocity data are referenced to the bottom, however, these can only be obtained when the water depth is within 1.5 times the depth of the ADCP profiling range.
Due to an incorrect setup, heading was not being recorded initially so it was not possible to get satisfactory bottom track data at the beginning of the cruise. Water track calibration was considered as a second choice. However, the cruise did not have a large amount of transition from on to off station data, which is fundamental to obtain an accurate estimation, and therefore no reliable corrections were obtained.
To get the angle of rotation, a new source of heading was imposed on data from the start of the cruise where bottom track had been recorded with an incorrect setup. The new source of heading was from the Seapath 200. The corrections were estimated to be 1 for amplitude and -0.8 for phase.
Interference
During the cruise, it was observed that the data quality was affected periodically at a changing depth. It is thought that this may be explained by other acoustic instruments with a similar frequency, creating a phased interference.
References
Cunningham, S. A. et al. 'RRS James Cook Cruise JC064, 10 Sep - 09 Oct 2011. RAPID moorings cruise report. Southampton, UK: National Oceanography Centre, Southampton, 183pp, National Oceanography Centre Cruise Report, No 14.'
BODC processing
The data were converted from Mstar format into BODC internal format, a netCDF subset, to allow use of in-house visualisation tools. The table below shows the mapping of originator variables to BODC Parameter codes.
Originator's variable | Units | Description | BODC Parameter Code | Units | Comments |
---|---|---|---|---|---|
lon | Degrees | Longitude | ALONGP01 | Degrees | - |
lat | Degrees | Latitude | ALATGP01 | Degrees | - |
depth (of bin) | m | Depth of ADCP bin | DBINAA01 | m | - |
uabs | cm s-1 | Absolute Eastward current velocity | LCEWAS01 | cm s-1 | - |
vabs | cm s-1 | Absolute Northward current velocity | LCNSAS01 | cm s-1 | - |
uship | m s-1 | Ship's Eastward velocity | APEWGP01 | cm s-1 | Values converted by multiplication by 100. |
vship | m s-1 | Ship's Northward velocity | APNSGP01 | cm s-1 | Values converted by multiplication by 100. |
speed | cm s-1 | Scalar current speed | - | - | Variable not transferred. Superseded by vector values |
shipspd | cm s-1 | Scalar ship speed | - | - | Variable not transferred. Superseded by vector values |
Reformatted data were visually checked using the in-house editor EDSERPLO. No data values were edited or deleted. Flagging was achieved by modification of the associated quality control flag to 'M' for suspect values and 'N' for nulls.
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
Monitoring the Meridional Overturning Circulation at 26.5N (RAPIDMOC)
Scientific Rationale
There is a northward transport of heat throughout the Atlantic, reaching a maximum of 1.3PW (25% of the global heat flux) around 24.5°N. The heat transport is a balance of the northward flux of a warm Gulf Stream, and a southward flux of cooler thermocline and cold North Atlantic Deep Water that is known as the meridional overturning circulation (MOC). As a consequence of the MOC northwest Europe enjoys a mild climate for its latitude: however abrupt rearrangement of the Atlantic Circulation has been shown in climate models and in palaeoclimate records to be responsible for a cooling of European climate of between 5-10°C. A principal objective of the RAPID programme is the development of a pre-operational prototype system that will continuously observe the strength and structure of the MOC. An initiative has been formed to fulfill this objective and consists of three interlinked projects:
- A mooring array spanning the Atlantic at 26.5°N to measure the southward branch of the MOC (Hirschi et al., 2003 and Baehr et al., 2004).
- Additional moorings deployed in the western boundary along 26.5°N (by Prof. Bill Johns, University of Miami - project MOCHA) to resolve transport in the Deep Western Boundary Current (Bryden et al., 2005). These moorings allow surface-to-bottom density profiles along the western boundary, Mid-Atlantic Ridge, and eastern boundary to be observed. As a result, the transatlantic pressure gradient can be continuously measured.
- Monitoring of the northward branch of the MOC using submarine telephone cables in the Florida Straits (Baringer et al., 2001) led by Dr Molly Baringer (NOAA/AOML/PHOD) - Western Boundary Time Series (WBTS) project.
The UK-led monitoring array system was recovered and redeployed annually until 2008 under RAPID funding. From 2008 until 2015 the array continued to be serviced annually under RAPID-WATCH funding. From 2015 until 2021 the array was serviced under RAPID-AMOC funding. Since 2022 the servicing of the array has continued to be funded by the Natural Environment Research Council (NERC). The US-led projects are funded by the National Science Foundation (NSF) (MOCHA project) and NOAA Office of Climate Observations (WBTS project).
The array will be focussed on three regions, the Eastern Boundary (EB), the Mid Atlantic Ridge (MAR) and the Western Boundary (WB). The geographical extent of these regions are as follows:
- Eastern Boundary (EB) array defined as a box with the south-east corner at 23.5°N, 25.5°W and the north-west corner at 29.0°N, 12.0°W
- Mid Atlantic Ridge (MAR) array defined as a box with the south-east corner at 23.0°N, 52.1°W and the north-west corner at 26.5°N, 40.0°W
- Western Boundary (WB) array defined as a box with the south-east corner at 26.0°N, 77.5°W and the north-west corner at 27.5°N, 69.5°W
References
Baehr, J., Hirschi, J., Beismann, J.O. and Marotzke, J. (2004) Monitoring the meridional overturning circulation in the North Atlantic: A model-based array design study. Journal of Marine Research, Volume 62, No 3, pp 283-312.
Baringer, M.O'N. and Larsen, J.C. (2001) Sixteen years of Florida Current transport at 27N Geophysical Research Letters, Volume 28, No 16, pp3179-3182
Bryden, H.L., Johns, W.E. and Saunders, P.M. (2005) Deep Western Boundary Current East of Abaco: Mean structure and transport. Journal of Marine Research, Volume 63, No 1, pp 35-57.
Hirschi, J., Baehr, J., Marotzke J., Stark J., Cunningham S.A. and Beismann J.O. (2003) A monitoring design for the Atlantic meridional overturning circulation. Geophysical Research Letters, Volume 30, No 7, article number 1413 (DOI 10.1029/2002GL016776)
RAPID- Will the Atlantic Thermohaline Circulation Halt? (RAPID-WATCH)
RAPID-WATCH (2007-2014) is a continuation programme of the Natural Environment Research Council's (NERC) Rapid Climate Change (RAPID) programme. It aims to deliver a robust and scientifically credible assessment of the risk to the climate of UK and Europe arising from a rapid change in the Atlantic Meridional Overturning Circulation (MOC). The programme will also assess the need for a long-term observing system that could detect major MOC changes, narrow uncertainty in projections of future change, and possibly be the start of an 'early warning' prediction system.
The effort to design a system to continuously monitor the strength and structure of the North Atlantic MOC is being matched by comparative funding from the US National Science Foundation (NSF) for the existing collaborations started during RAPID for the observational arrays.
Scientific Objectives
- To deliver a decade-long time series (2004-2014) of calibrated and quality-controlled measurements of the Atlantic MOC from the RAPID-WATCH arrays.
- To exploit the data from the RAPID-WATCH arrays and elsewhere to determine and interpret recent changes in the Atlantic MOC, assess the risk of rapid climate change, and investigate the potential for predictions of the MOC and its impacts on climate.
This work will be carried out in collaboration with the Hadley Centre in the UK and through international partnerships.
Mooring Arrays
The RAPID-WATCH arrays are the existing 26°N MOC observing system array (RAPIDMOC) and the WAVE array that monitors the Deep Western Boundary Current. The data from these arrays will work towards meeting the first scientific objective.
The RAPIDMOC array consists of moorings focused in three geographical regions (sub-arrays) along 26.5° N: Eastern Boundary, Mid-Atlantic Ridge and Western Boundary. The Western Boundary sub-array has moorings managed by both the UK and US scientists. The other sub-arrays are solely led by the UK scientists. The lead PI is Dr Stuart Cunningham of the National Oceanography Centre, Southampton, UK.
The WAVE array consists of one line of moorings off Halifax, Nova Scotia. The line will be serviced in partnership with the Bedford Institute of Oceanography (BIO), Halifax, Canada. The lead PI is Dr Chris Hughes of the Proudman Oceanographic Laboratory, Liverpool, UK.
All arrays will be serviced (recovered and redeployed) either on an annual or biennial basis using Research Vessels from the UK, US and Canada.
Modelling Projects
The second scientific objective will be addressed through numerical modelling studies designed to answer four questions:
- How can we exploit data from the RAPID-WATCH arrays to obtain estimates of the MOC and related variables?
- What do the observations from the RAPID-WATCH arrays and other sources tell us about the nature and causes of recent changes in the Atlantic Ocean?
- What are the implications of RAPID-WATCH array data and other recent observations for estimates of the risk due to rapid change in the MOC?
- Could we use RAPID-WATCH and other observations to help predict future changes in the MOC and climate?
Data Activity or Cruise Information
Cruise
Cruise Name | JC064 |
Departure Date | 2011-09-10 |
Arrival Date | 2011-10-09 |
Principal Scientist(s) | Stuart A Cunningham (National Oceanography Centre, Southampton) |
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 |