Metadata Report for BODC Series Reference Number 770693
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Open Data supplied by Natural Environment Research Council (NERC)
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Sea-Bird SBE 37-IMP MicroCAT
The SBE 37-IMP MicroCAT is a high accuracy conductivity and temperature recorder (pressure optional) with a built in Inductive Modem and integral Pump. Designed for moorings and other long-duration, fixed-site deployments, MicroCATs have non-corroding titanium housings rated for operation to 7000 meters or pressure sensor full scale-range.
The Inductive Modem provides reliable, low-cost, real-time data transmission. The Integral Pump runs for 1 second each time the MicroCAT samples, improving the conductivity response and giving improved anti-foul protection.
Communication with the MicroCAT is via a Surface Inductive Modem (SIM) to a computer or data logger. Commands and data are transmitted half-duplex between the SIM and the MicroCAT using DPSK (differential-phase-shift-keyed) telemetry. As a safe guard, the MicroCAT simultaneously backs up the data in its non-volatile internal memory as well as transmitting the data via telemetry.
The MicroCAT's aged and pressure-protected thermistor has a long history of exceptional accuracy and stability (typical drift is less than 0.002°C per year). Electrical isolation of the conductivity electronics eliminates any possibility of ground-loop noise.
|Conductivity (S/m)||Optional Pressure|
|Measurement Range||-5 to +35||0 to 7 (0 to 70 mS/cm)||0 to full scale range: 20 / 100 / 350 / 600 / 1000 / 2000 / 3500 / 7000 metres|
|Initial accuracy||0.002||0.0003||0.1% of full scale range|
|Typical Stability||0.0002||0.0003||0.05% of full scale range per year|
|Resolution||0.0001||0.00001||0.002% of full scale range|
|Data Storage||Temperature and conductivity: 6 bytes per sample |
Time: 4 bytes per sample
Pressure (optional): 5 bytes per sample
|Clock accuracy||5 seconds per month|
|Standard Internal Batteries||Nominal 10.6 Ampere-hour pack consisting of twelve AA lithium batteries. Provides sufficient capacity for more than 85,000 samples for a typical sampling scheme|
|Housing||Titanium pressure case rated at 7000 metres|
|Weight (without pressure)||In water: 3.1kg |
In air: 5.2kg
Further information can be found via the following link: Sea-Bird SBE 37-IMP MicroCAT Datasheet
RAPIDMOC Calibration Coefficients: Series 770693
|BODC Series identifier||770693|
|Instrument Serial number||4799|
|Deployment Cruise||FS Poseidon cruise PO343|
|Recovery Cruise||RRS Discovery cruise D324|
Pre and post cruise coefficients were averaged and applied as constant offsets to all three channels
Average conductivity applied? y
Average temperature applied? y
Average pressure applied? y
Pressure drift removal? n
Conductivity pressure correction redone? n
Skipped conductivity intervals: 
Skipped temperature intervals : 
Skipped pressure intervals : 
Number of additional C points skipped interactively: 
Number of additional C points skipped automatically: 
RAPIDMOC/MOCHA Sea-Bird MicroCAT data processing document
This document outlines the procedures undertaken to process and quality assure the MicroCAT data collected under the RAPIDMOC and MOCHA projects.
The raw data are downloaded from the instrument and converted to ASCII format. All processing is performed in Matlab.
Calculating calibration coefficients
Prior to deployment and on recovery, a CTD dip is performed with the MicroCATs strapped onto the CTD frame. This allows calibration of the MicroCAT data by comparing the MicroCAT data with the CTD data. As the MicroCATs adjustment is much slower than the CTD, data are only compared during bottle stops and after the sensors have adjusted. Bottle stops on these calibration dips last no less than 5 minutes.
Any discrepancy between the MicroCAT clock and the CTD clock is calculated and corrected if necessary.
An average offset (MicroCAT - CTD) is calculated for temperature, conductivity and pressure during the stable period of each bottle stop and interpolated onto the instrument deployment depths. For temperature and conductivity, an average of the offsets derived during the bottle stops is calculated for a specified pressure range where the data are stable (deep water). For pressure, the average offset interpolated to the deployment depth is used. If the calibration dip is shallower than the deployment depth, the offset is extrapolated to the deployment depth.
All the offsets are visually checked and adjusted if necessary.
The data are calibrated using the pre and post deployment calibration coefficients. The calibration can be applied as either
- A linear trend between the pre and post deployment coefficients
- A constant offset using the pre deployment coefficient
- A constant offset using the post deployment coefficient
- A constant offset using an average of the pre and post deployment coefficients
- A general linear trend using either the pre or post deployment coefficient
If required, a conductivity pressure correction can be applied. This is used if the pressure channel shows spurious data in a particular time interval. A drift in the pressure data can also be removed.
To aid the quality of the calibration, data from CTD casts performed near mooring locations on previous cruises are used as a reference and are visually compared with the MicroCAT data.
All variables in specified time intervals can be set to dummy values if the data are suspect and it is also possible to apply an offset to a subsection of a particular channel, if required. Interactive despiking can be carried out on the temperature and conductivity data, if present, by selecting data based on a T-S plot. Automatic despiking can also be performed using the option to exclude data outside the 6σ area.
The last stage of the processing is to grid the data onto a pressure field and visually check against historical data. This enables the calibrations to be checked and adjusted if necessary. On occasion, comparison of the time series with historical data and series from nearby instruments highlights the need for removal of a drift from one or more data channels. This is accomplished by removing a linear trend from the appropriate channel(s) and may affect the entire series or a subsection thereof. If a trend has been removed it will be noted in the 'RAPIDMOC Calibration Coefficients' section of the documentation.
Data are received after quality checks have been made and calibrations have been applied. The data files are submitted in ASCII format as one file per instrument.
Once the submitted data files are safely archived, the data undergo reformatting and banking procedures:
The data files are transferred into a common format, a NetCDF subset.
Standard parameter codes are assigned that accurately describe the data (see Parameter mapping section below).
Unit conversions are applied, if necessary, so that units are standardised (see Parameter mapping section below).
Salinity is derived using UNESCO 1983 polynomial.
The data are screened visually and any spikes or instrument malfunctions can be clearly labelled with quality control flags.
Comprehensive documentation is prepared describing the collection, processing and quality of each data series.
Detailed metadata and documents are loaded to the database and linked to each series so that the information is readily available to future users.
The following describes the parameters contained in the originator's files and their mapping to BODC parameter codes:
|Identifier||Unit||Definition||BODC parameter code||Units||Unit conversion||Comments|
|YY||year||Year||AADYAA01||days||-||Combined with MM and DD to form a date and transferred|
|MM||month||Month||AADYAA01||days||-||Combined with MM and DD to form a date and transferred|
|DD||day||Day||AADYAA01||days||-||Combined with MM and DD to form a date and transferred|
The following describes the parameters derived by BODC and their mapping to BODC parameter codes:
|BODC parameter code||Units||Variables||Definition||Units||Equation||Comments|
|UNESCO 1983 polynomial for salinity||-|
Rapid Climate Change (RAPID) Programme
Rapid Climate Change (RAPID) is a £20 million, six-year (2001-2007) programme of the Natural Environment Research Council (NERC). The programme aims to improve our ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.
- To establish a pre-operational prototype system to continuously observe the strength and structure of the Atlantic Meridional Overturning Circulation (MOC).
- To support long-term direct observations of water, heat, salt, and ice transports at critical locations in the northern North Atlantic, to quantify the atmospheric and other (e.g. river run-off, ice sheet discharge) forcing of these transports, and to perform process studies of ocean mixing at northern high latitudes.
- To construct well-calibrated and time-resolved palaeo data records of past climate change, including error estimates, with a particular emphasis on the quantification of the timing and magnitude of rapid change at annual to centennial time-scales.
- To develop and use high-resolution physical models to synthesise observational data.
- To apply a hierarchy of modelling approaches to understand the processes that connect changes in ocean convection and its atmospheric forcing to the large-scale transports relevant to the modulation of climate.
- To understand, using model experimentation and data (palaeo and present day), the atmosphere's response to large changes in Atlantic northward heat transport, in particular changes in storm tracks, storm frequency, storm strengths, and energy and moisture transports.
- To use both instrumental and palaeo data for the quantitative testing of models' abilities to reproduce climate variability and rapid changes on annual to centennial time-scales. To explore the extent to which these data can provide direct information about the thermohaline circulation (THC) and other possible rapid changes in the climate system and their impact.
- To quantify the probability and magnitude of potential future rapid climate change, and the uncertainties in these estimates.
Overall 38 projects have been funded by the RAPID programme. These include 4 which focus on Monitoring the Meridional Overturning Circulation (MOC), and 5 international projects jointly funded by the Netherlands Organisation for Scientific Research, the Research Council of Norway and NERC.
The RAPID effort to design a system to continuously monitor the strength and structure of the North Atlantic Meridional Overturning Circulation is being matched by comparative funding from the US National Science Foundation (NSF) for collaborative projects reviewed jointly with the NERC proposals. Three projects were funded by NSF.
A proportion of RAPID funding as been made available for Small and Medium Sized Enterprises (SMEs) as part of NERC's Small Business Research Initiative (SBRI). The SBRI aims to stimulate innovation in the economy by encouraging more high-tech small firms to start up or to develop new research capacities. As a result 4 projects have been funded.
Monitoring the Meridional Overturning Circulation at 26.5N (RAPIDMOC)
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
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)
|Start Date (yyyy-mm-dd)||2006-10-07|
|End Date (yyyy-mm-dd)||2007-11-06|
|Organization Undertaking Activity||National Oceanography Centre, Southampton|
|Country of Organization||United Kingdom|
|Originator's Data Activity Identifier||EBH4#4|
|Platform Category||subsurface mooring|
RAPID Moored Instrument Rig EBH4#4
This rig was deployed as part of the Eastern Boundary (EB) array of the RAPIDMOC project.
|Deployment Cruise||FS Poseidon PO343|
|Recovery Cruise||RRS Discovery cruise D324|
This rig was anchored by 600 kg of railway wheels and was kept erect by groups of sub-surface floats attached along the mooring.
Instruments deployed on the rig
|602 m||Sea-Bird SBE37 IMP MicroCAT (#4470)|
|706 m||Sea-Bird SBE37 IMP MicroCAT (#4799)|
|835 m||Sea-Bird SBE37 IMP MicroCAT (#4800)|
|Principal Scientist(s)||Torsten Kanzow (National Oceanography Centre, Southampton)|
Complete Cruise Metadata Report is available here
Fixed Station Information
|Station Name||Eastern Boundary Array|
|Latitude||25° 51.60' N|
|Longitude||18° 43.98' W|
|Water depth below MSL|
RAPIDMOC Eastern Boundary (EB) Array
The Eastern Boundary Array defines a box in which moorings are deployed at the eastern side of the North Atlantic as part of the RAPIDMOC project. The box region has latitudinal limits of 23.5° N to 29° N and longitudinal limits of 12° W to 25.5° W. Moorings have occupied this region since 2004 and are typically deployed for 6 to 18 months.
Moored data summary
A description of the data types can be found at the bottom of this document.
|Year||Cruise ID||Number of moorings||Data types (number of instruments)|
|2004||D277, PO319||11||BPR (7), CM (10), MCTD (32)|
|2005||CD170,CD177||15||ADCP (1), BPR (4), CM (4), MCTD (71), IES (2), MMP (1)|
|2006||D304, PO343, PO345||24||BPR (6), CM (4), MCTD (78), MMP (1)|
|2007||D324||13||BPR (3), MCTD (53), IES (2)|
|2008||D334||14||BPR (3), CM (2), MCTD (44), IES (1)|
|2009||D344||14||BPR (4), CM (2), MCTD (44)|
|2011||D359, JC064||22||BPR (12), CM (18), MCTD (80), IES (1)|
|2012||D382||9||BPR (6), CM (10), MCTD (50)|
Cruise data summary
During the cruises to service the moored array, a variety of data types are collected. The table below is a summary of these data. The number of CTD profiles performed on these cruises within the box region defined above is also included. Trans-Atlantic hydrographic CTD sections have also been performed since 2004 and are included in the table.
|Cruise ID||Cruise description||Data types||Number of CTD profiles performed within the box region|
|D277||Initial array deployment||MET, NAV, SADCP, SURF||-|
|D279||Hydrographic section||CTD, DIS, LADCP, MET, NAV, SADCP, SURF||21|
|CD170||Array service||BATH, CTD, DIS, MET, NAV, SADCP, SURF||4|
|CD177||Array service||BATH, CTD, DIS, MET, NAV, SADCP, SURF||6|
|D304||Array service||CTD, DIS, MET, NAV, SADCP, SURF||8|
|PO343||Array service||CTD, DIS, MET, NAV, SADCP, SURF||5|
|PO345||Array service||CTD, DIS, MET, NAV, SADCP, SURF||4|
|D324||Array service||CTD, DIS, MET, NAV, SADCP, SURF||5|
|D334||Array service||CTD, DIS, MET, NAV, SADCP, SURF||15|
|D344||Array service||CTD, DIS, MET, NAV, SADCP, SURF||5|
|D346||Hydrographic section||CTD, DIS, LADCP, MET, NAV, SADCP, SURF||22|
|D359||Array service||CTD, DIS, MET, NAV, SADCP, SURF||4|
|JC064||Array service||CTD, DIS, MET, NAV, SADCP, SURF||5|
|D382||Array service||CTD, DIS, MET, NAV, SADCP, SURF||5|
Data type ID and description
|Data type ID||Description|
|ADCP||Acoustic Doppler Current Profiler|
|BPR||Bottom Pressure Recorder|
|DIS||Discrete water bottle samples|
|IES||Inverted Echo Sounder|
|LADCP||Lowered Acoustic Doppler Current Profiler|
|MCTD||Moored Conductivity-Temperature-Depth sensor|
|MMP||McLane Moored Profiler - profiling CTD and current meter|
|SADCP||Shipborne Acoustic Doppler Current Profiler|
|SURF||Sea surface data|
Other Cruises linked to this Fixed Station (with the number of series) - CD170 (52) CD177 (31) D277 (39) D304 (57) D324 (61) D334 (44) D344 (48) D346 (22) D359 (44) D382 (5) JC064 (46) PO343 (9) PO345 (30)
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
|<||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.)|
|E||End of CTD Down/Up Cast|
|G||Non-taxonomic biological characteristic uncertainty|
|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|
|O||Improbable value - user quality control|