Metadata Report for BODC Series Reference Number 1926249
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
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
RAPID Cruise JC145 75kHz Shipboard ADCP data processing
Originator's Processing
The following was taken from the JC145 cruise report. For more detailed information please refer to Smeed (2017). Data were collected using a Teledyne RDI Ocean Surveyor 75kHz vessel-mounted ADCP. The data were then acquired using the RD Instruments VmDas software package version 1.42.
ADCP setup
Variable | Setting |
---|---|
Number of Bins | 48 |
Bin size | 16m |
Blanking distance | 8m |
Transducer depth | 6m |
Processing mode | Narrowband mode: bottom-tracking and water-tracking |
Maximum range | 1200m |
Post-processing
The final processing of data was done using the CODAS (Common Ocean Data Access System) suite of software. The processing route can be summarised as copying the raw files, converting them into a working format, merging navigation data, deriving velocities, quality control, and conversion of data to Matlab and NetCDF files.
Calibration
The ADCP was configured in bottom-tracking mode for the initial steam from Southampton, 15th February 2017 to 25th February 2017. Subsequently it was configured in water-tracking mode.
An adjustment to the instrument alignment angle was made on 5th April 2017. The final angle was -10.0° and the amplitude was 1.0.
Data quality
The computer running VMDAS had recurring problems serving its network mounts. The 75kHz data appear to be affected by a scattering layer around 300-500m depth, visible as a local amplitude maximum and an approximate 30 m deep band of forward ocean velocity bias (the aft-biased layer is not evident).
References
Smeed, D. 2017. RRSJames Cook Cruise JC145, 28 Feb - 04 April 2017. RAPID Cruise Report. Southampton, UK: National Oceanography Centre, Southampton, 179pp., National Oceanography Centre Cruise Report, No 52.
BODC Processing
The data were provided to BODC in one MStar file and were then reformatted to BODC's internal NetCDF format. The following table shows the mapping of variables within the Matlab files to appropriate BODC parameter codes:
Originator's Variable | Originator's Units | BODC Parameter Code | BODC Units | Comment |
---|---|---|---|---|
uabs | cm/s | LCEWAS01 | cm/s | Eastward values are positive |
vabs | cm/s | LCNSAS01 | cm/s | Northward values are positive |
uship | m/s | APEWGP01 | cm/s | Conversion *100 applied |
vship | m/s | APNSGP01 | cm/s | Conversion *100 applied |
speed | cm/s | - | - | Not transferred |
shipspd | m/s | - | - | Not transferred |
depth | metres | DBINAA01 | metres | - |
lat | degrees | ALATGP01 | degrees | - |
lon | degrees | ALONGP01 | degrees | Conversion -360 applied |
decday | days | AADYAA01 | days | - |
time | seconds | AAFDZZ01 | days | Conversion automatically applied during transfer |
The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag.
Although the ADCP was configured during the sailing between 15th February 2017 to 25th February 2017, the cruise did not actually begin until 28th February, so all data from before the 28th were removed from the data file as they are not part of cruise JC145.
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) 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).
The entire monitoring array system created by the three projects will be recovered and redeployed annually until 2008 under RAPID funding. From 2008 until 2014 the array will continue to be serviced annually under RAPID-WATCH funding.
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 Climate Change - Atlantic Meridional Overturning Circulation (RAPID-AMOC)
RAPID-AMOC is an £8.4 million, 7 year (2013-2020) research programme that builds on the success of the Natural Environment Research Council's (NERC) RAPID and RAPID-WATCH programmes and will deliver a 16 year long time series of the Atlantic Meridional Overturning Circulation (AMOC).
Background
The Atlantic Meridional Overturning Circulation (AMOC) is a critical element in the energy balance of the global climate system. The AMOC consists of a near-surface, warm northward flow of ocean water, compensated by a colder southward return flow at depth. This heat is transferred from the ocean to the atmosphere at mid-latitudes, with a substantial impact on climate and, in particular, on that of the UK and northwest Europe.
Observing and understanding changes in the AMOC is critically important for identifying the mechanisms of decadal climate variability and change, and for interannual-to-decadal climate prediction. This includes predicting changes in the location, frequency and intensity of Atlantic hurricanes, storms in the North Atlantic and over Europe, shifts in tropical and European precipitation patterns, and the response of sea level to changing radiative forcing. Sustained observations are also critical for assessing the possibility of abrupt change in the AMOC that are known to occur in palaeoclimatic records.
Since 2004 the NERC RAPID and RAPID-WATCH programmes, in partnership with the National Science Foundation and the National Oceanic and Atmospheric Administration in the US, have supported an observing system to continuously measure the AMOC at 26.5°N via a trans-basin array of moored instruments. This measures the basin-wide strength and vertical structure of the AMOC, and its components.
Observations from the array have already revolutionised understanding of AMOC variability and documented its variability on seasonal to interannual timescales. The first few years of observations, demonstrated the feasibility of AMOC measurement, provided new insights into the seasonal cycle, and allowed apparent trends in previous historical 'snapshots' to be seen in the context of natural variability. RAPID-AMOC will extend the AMOC time series.
Objective
RAPID-AMOC's overall objective is to determine the variability of the AMOC, and its links to climate and to the ocean carbon sink, on interannual-to-decadal time scales
This will be achieved by the continued support of the monitoring array and supporting the use of the data in three key areas:
- Application of array data for improved ocean state estimation;
- Use of array data to understand the role of the AMOC in climate variability and predictability;
- Addition of biogeochemical sensors to the array and use to constrain biogeochemical fluxes.
Three projects have been funded to address the objectives of RAPID-AMOC:
- Reanalysis of the AMOC
- DYNamics and predictability of the Atlantic Meridional Overturning and Climate (DYNAMOC)
- Atlantic BiogeoChemical fluxes (ABC Fluxes)
Data Activity or Cruise Information
Cruise
Cruise Name | JC145 |
Departure Date | 2017-02-28 |
Arrival Date | 2017-04-08 |
Principal Scientist(s) | David Smeed (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 |