Metadata Report for BODC Series Reference Number 1047256
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
Public domain 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.
The recommended acknowledgment is
"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."
Narrative Documents
Sea-Bird Dissolved Oxygen Sensor SBE 43 and SBE 43F
The SBE 43 is a dissolved oxygen sensor designed for marine applications. It incorporates a high-performance Clark polarographic membrane with a pump that continuously plumbs water through it, preventing algal growth and the development of anoxic conditions when the sensor is taking measurements.
Two configurations are available: SBE 43 produces a voltage output and can be incorporated with any Sea-Bird CTD that accepts input from a 0-5 volt auxiliary sensor, while the SBE 43F produces a frequency output and can be integrated with an SBE 52-MP (Moored Profiler CTD) or used for OEM applications. The specifications below are common to both.
Specifications
Housing | Plastic or titanium |
Membrane | 0.5 mil- fast response, typical for profile applications 1 mil- slower response, typical for moored applications |
Depth rating | 600 m (plastic) or 7000 m (titanium) 10500 m titanium housing available on request |
Measurement range | 120% of surface saturation |
Initial accuracy | 2% of saturation |
Typical stability | 0.5% per 1000 h |
Further details can be found in the manufacturer's specification sheet.
OC421 CTD instrument description
CTD unit and auxiliary sensors
A Sea-Bird 911 plus system was used on cruise OC421 (coupled with a Sea-Bird 917 plus for in-situ recording). This was mounted on a stainless steel rosette frame, equipped with 24 water sampling bottles (23 bottles had a 10 litre capacity, the remaining one had 4 litre capacity). Further details regarding the full CTD package can be found below:
Sensor | Serial Number | Comments |
---|---|---|
Digiquartz Pressure Sensor | 94763 | - |
Primary Sea-Bird Temperature Sensor | 4502 | - |
Secondary Sea-Bird Temperature Sensor | 4507 | Not included in final WHOI data set. |
Primary Sea-Bird Conductivity Sensor | 3089 | - |
Secondary Sea-Bird Conductivity Sensor | 3093 | Not included in final WHOI data set. |
Sea-Bird SBE 43 Oxygen Sensor | 0772 | - |
Wetlabs ECO-AFL/FL Fluorometer | 0304 | Not included in final WHOI data set. |
Wetlabs C-Star Transmissometer | 0854 | Not included in final WHOI data set. |
Altimeter | 997 | Not included in final WHOI data set. |
Sea-Bird Electronics SBE 911 and SBE 917 series CTD profilers
The SBE 911 and SBE 917 series of conductivity-temperature-depth (CTD) units are used to collect hydrographic profiles, including temperature, conductivity and pressure as standard. Each profiler consists of an underwater unit and deck unit or SEARAM. Auxiliary sensors, such as fluorometers, dissolved oxygen sensors and transmissometers, and carousel water samplers are commonly added to the underwater unit.
Underwater unit
The CTD underwater unit (SBE 9 or SBE 9 plus) comprises a protective cage (usually with a carousel water sampler), including a main pressure housing containing power supplies, acquisition electronics, telemetry circuitry, and a suite of modular sensors. The original SBE 9 incorporated Sea-Bird's standard modular SBE 3 temperature sensor and SBE 4 conductivity sensor, and a Paroscientific Digiquartz pressure sensor. The conductivity cell was connected to a pump-fed plastic tubing circuit that could include auxiliary sensors. Each SBE 9 unit was custom built to individual specification. The SBE 9 was replaced in 1997 by an off-the-shelf version, termed the SBE 9 plus, that incorporated the SBE 3 plus (or SBE 3P) temperature sensor, SBE 4C conductivity sensor and a Paroscientific Digiquartz pressure sensor. Sensors could be connected to a pump-fed plastic tubing circuit or stand-alone.
Temperature, conductivity and pressure sensors
The conductivity, temperature, and pressure sensors supplied with Sea-Bird CTD systems have outputs in the form of variable frequencies, which are measured using high-speed parallel counters. The resulting count totals are converted to numeric representations of the original frequencies, which bear a direct relationship to temperature, conductivity or pressure. Sampling frequencies for these sensors are typically set at 24 Hz.
The temperature sensing element is a glass-coated thermistor bead, pressure-protected inside a stainless steel tube, while the conductivity sensing element is a cylindrical, flow-through, borosilicate glass cell with three internal platinum electrodes. Thermistor resistance or conductivity cell resistance, respectively, is the controlling element in an optimized Wien Bridge oscillator circuit, which produces a frequency output that can be converted to a temperature or conductivity reading. These sensors are available with depth ratings of 6800 m (aluminium housing) or 10500 m (titanium housing). The Paroscientific Digiquartz pressure sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.
Additional sensors
Optional sensors for dissolved oxygen, pH, light transmission, fluorescence and others do not require the very high levels of resolution needed in the primary CTD channels, nor do these sensors generally offer variable frequency outputs. Accordingly, signals from the auxiliary sensors are acquired using a conventional voltage-input multiplexed A/D converter (optional). Some Sea-Bird CTDs use a strain gauge pressure sensor (Senso-Metrics) in which case their pressure output data is in the same form as that from the auxiliary sensors as described above.
Deck unit or SEARAM
Each underwater unit is connected to a power supply and data logging system: the SBE 11 (or SBE 11 plus) deck unit allows real-time interfacing between the deck and the underwater unit via a conductive wire, while the submersible SBE 17 (or SBE 17 plus) SEARAM plugs directly into the underwater unit and data are downloaded on recovery of the CTD. The combination of SBE 9 and SBE 17 or SBE 11 are termed SBE 917 or SBE 911, respectively, while the combinations of SBE 9 plus and SBE 17 plus or SBE 11 plus are termed SBE 917 plus or SBE 911 plus.
Specifications
Specifications for the SBE 9 plus underwater unit are listed below:
Parameter | Range | Initial accuracy | Resolution at 24 Hz | Response time |
---|---|---|---|---|
Temperature | -5 to 35°C | 0.001°C | 0.0002°C | 0.065 sec |
Conductivity | 0 to 7 S m-1 | 0.0003 S m-1 | 0.00004 S m-1 | 0.065 sec (pumped) |
Pressure | 0 to full scale (1400, 2000, 4200, 6800 or 10500 m) | 0.015% of full scale | 0.001% of full scale | 0.015 sec |
Further details can be found in the manufacturer's specification sheet.
OC421 CTD data processing
Sampling Strategy
A total of 17 CTD casts were performed during the cruise, extending from the Line W mooring array, south, across the Gulf Stream. Data were obtained at 24 Hz resolution by a Sea-Bird Electronic Model 11 plus CTD Deck Unit and transferred to a personal computer equipped with Sea-Bird processing software.
Originator data processing
Processing was carried out after each cast using Sea-Bird Electronics SeaSoft data conversion software. The table below summarises the Sea-Bird programs that were used to process the data:
Sea-Bird program | Summary of processing step |
---|---|
DATCNV | Conversion of raw (binary) files to engineering units and ASCII (.CNV) |
ROSSUM | Generation of Sea-Bird bottle data files (.BTL) with information on pressure and other readings logged at bottle firing time |
ALIGNCTD | Advances the conductivity by approximately 0.073 seconds relative to pressure |
WILDEDIT | Marks anomalous data points (first pass 2.0 standard deviations, second pass 20 standard deviations) |
CELLTM | Compensates for the effects of the thermal mass of the conductivity cell using Sea-Bird recommended values: alpha = 0.03 and 1/beta=7 |
FILTER | Smoothes out response time issues in the sensors. Run on conductivity and pressure with time constants of approximately 0.03 and 0.15 seconds respectively |
LOOPEDIT | Marks scans where the CTD was moving less than a minimum velocity of 0.1 m s-1 in order to remove scans where the ship's heave caused the CTD package to travel backwards |
DERIVE | Computes oxygen from the oxygen current, temperature and pressure |
BINAVG | Averages the data into 2 dbar pressure bins |
DERIVE | Computes salinity |
STRIP | Removes unwanted columns of data from the .CNV files |
TRANS | Changes the .CNV ASCII format to binary |
SPLIT | Generates upcast and downcast files of data |
Field calibrations
Pressure
Sea surface pressure bias was observed at the end of each cast to ensure that drift was not a significant issue. Pressure bias ranged between 0.2 and -0.4 dbar, but no corrections were made.
Conductivity
The primary conductivity sensor data were compared with concurrent discrete bottle conductivities to find the best fit for calibration purposes. Full details of this are available in the WHOI CTD calibration report.
Temperature
A history of the temperature sensor calibration was used to create a bias, which was then applied to the primary temperature channel data. No further details are known.
Oxygen
Calibration of the oxygen sensor data was performed last, due to a weak dependence on CTD pressure, temperature and conductivity. Sensor data were compared with concurrent discrete bottle oxygen measurements to find a suitable fit. The precise details of the calibration procedure are also documented in the WHOI CTD calibration report.
Data dissemination
(WOCE Standard) ASCII, HydroBase and netCDF formatted versions of each CTD cast were uploaded to the Line W project website with no access restrictions applied.
BODC processing
WOCE formatted versions of each cast were downloaded (during May 2008) from the Line W website data download area for inclusion in the RAPID WAVE data archive. Copies of these archived files were reformatted to BODC's internal netCDF format. WOCE warning flags, if present in the originator's files, were mapped to BODC quality control flags. The following table shows the mapping of variables within the data files to appropriate BODC parameter codes:
Originator's variable | Units | Description | BODC parameter code | Units | Comments |
---|---|---|---|---|---|
CTDPRS | dB | Pressure exerted by the water column | PRESPR01 | dB | - |
CTDTMP | °C | Temperature of the water column by CTD | TEMPCC01 | °C | - |
CTDSAL | - | Practical salinity of the water column | PSALCC01 | - | - |
CTDOXY | µmol/kg | Dissolved oxygen concentration of the water column | DOXYSC01 | µmol/l | Unit conversion applied during BODC reformatting process (see below) |
The unit conversion of oxygen was performed as follows:
µmol/l = µmol/kg * ((potential density + 1000)/1000)
potential density was calculated in accordance with Fofonoff and Millard (1983), having first converted temperature from ITS-90 to IPTS-68.
The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag.
Detailed metadata and documentation were compiled and linked to the data.
References
Fofonoff, P. and Millard, R.C. Jr., UNESCO 1983. Algorithms for computation of fundamental properties of seawater, 1983. UNESCO Technical Papers in Marine Science. No. 44.
Project Information
Line W Project
Introduction
Line W is a U.S-led initiative to monitor the North Atlantic Ocean's deep western boundary current. The programme is funded through the U.S National Science Foundation and has been active since October 2001. It brings together scientists from Woods Hole Oceanographic Institution (WHOI) and Lamont-Doherty Earth Observatory (LDEO). Between 2004 and 2010, scientists from the RAPID WAVE project (a component of the U.K's RAPID Climate Change Programme) also collaborated with Line W. This U.K element was funded by the Natural Environment Research Council (NERC) and brought additional instrumentation (predominantly bottom pressure landers) to the mooring array. The contact details of the principal collaborators involved with Line W are noted below.
Users of these data are referred to the Line W Project Website for more information. The following text has been taken from the website.
Scientific Rationale
Located on the continental slope south of New England (near 40°N, 70°W) Line W is one component of a long-term climate observing system that is positioned to quantify variability in the deep limb of the Atlantic meridional overturning circulation (MOC). Combining an array of moored instruments with shipboard observations, Line W is designed to directly measure the time dependence of volume transport, advection of property anomalies, and propagation of topographic Rossby waves and boundary waves in the equatorward flowing deep western boundary current (DWBC). These measurements are key to clarifying the deep ocean response to variability in high-latitude air-sea exchanges and, ultimately, the ocean's role in global climate variability through changes in its transport of heat and freshwater.
Instrumentation
Types of instruments and measurements:
- Moored Profilers (temperature, salinity, velocity)
- Current meters (VACMs) with Temperature/Conductivity sensors and upward-looking ADCP
- Shipboard measurements: CTD, CFCs, salinity, dissolved oxygen, I129, LADCP, ADCP
The full array of instruments was installed April 2004 with servicing as follows:
- Annual spring turnaround for profilers
- 2-year turnaround for VACMs
- Twice yearly shipboard measurements
Contacts
Collaborator | Organisation | Project |
---|---|---|
Dr. John M. Toole | Woods Hole Oceanographic Institution, U.S | Line W |
Dr. Ruth Curry | Woods Hole Oceanographic Institution, U.S | Line W |
Dr. Terry Joyce | Woods Hole Oceanographic Institution, U.S | Line W |
Prof. William M. Smethie Jr. | Lamont-Doherty Earth Observatory, U.S | Line W |
Prof. Chris W. Hughes | National Oceanography Centre, U.K | RAPID WAVE |
Dr. Miguel Angel Morales Maqueda | National Oceanography Centre, U.K | RAPID WAVE |
Dr. Shane Elipot | National Oceanography Centre, U.K | RAPID WAVE |
Prof. Ric Williams | Department of Earth and Ocean Sciences, University of Liverpool, U.K | RAPID WAVE |
Prof. David Marshall | Department of Atmospheric, Oceanic and Planetary Physics, University of Oxford, U.K | RAPID WAVE |
RAPID Western Atlantic Variability Experiment (WAVE)
Introduction
The RAPID WAVE project began in 2004 as an observational component of the U.K Natural Environment Research Council's RAPID Climate Change Programme in the western North Atlantic Ocean. In 2008, funding to continue RAPID WAVE was secured through the continuation programme, RAPID-WATCH, which is due to end in 2014.
The RAPID WAVE team brings together scientists at the National Oceanography Centre in Liverpool. Between 2004 and 2010, the RAPID WAVE team also contributed to the Line W mooring array, joining colleagues from the U.S. Line W is a U.S-led initiative used to monitor the North Atlantic Ocean's deep western boundary current whilst being funded through the U.S National Science Foundation and has been active since October 2001. It brings together scientists from Woods Hole Oceanographic Institution (WHOI) and Lamont-Doherty Earth Observatory (LDEO). Users of these data are referred to the Line W Project Website for more information.
In 2007, further collaboration was established with scientists at the Bedford Institute of Oceanography (BIO). This arrangement was formalised and continues under RAPID-WATCH. Smaller scale collaboration with scientists at the Instituto Espanol de Oceanografia (IEO) during RAPID-WATCH saw additional RAPID WAVE observational work in the eastern North Atlantic Ocean. This work commenced in 2009 as part of the RAPID WAVE RAPIDO campaign.
Scientific Rationale
The primary aim of the RAPID WAVE project is to develop an observing system that will identify the propagation of overturning signals, from high to low latitudes, along the western margin of the North Atlantic. It specifically aims to monitor temporal changes in the Deep Western Boundary Current and reveal how coherent the changes are along the slope. Ultimately it is envisaged that this will enable scientists to develop a better understanding of larger-scale overturning circulation in the Atlantic, and its wider impacts on climate.
Fieldwork
The fieldwork aspect of the project was to deploy arrays of Bottom Pressure Recorders (BPRs) and CTD moorings along specified satellite altimeter groundtracks off the eastern continental slope of Canada and the United States. In 2004, fieldwork focused on three array lines. Line A was established heading south west from the Grand Banks, whilst the Line B array ran south east on the continental slope of Nova Scotia. The third line, Line W, was an established hydrographic array on the continental slope of New England, serviced by Woods Hole Oceanographic Institute (WHOI), to which RAPID WAVE contributed BPR instrumentation.
The original intention was that each array would be serviced by a cruise every two years. However, following a very poor return rate of instrumentation during the first servicing cruise of Lines A and B in 2006, this plan was modified significantly, and the decision made to abandon work on Line A. In 2007, additional logistical support from Canada's Bedford Institute of Oceanography (BIO) enabled Line B to be serviced again after just one year of deployment, with a much improved recovery record.
The transition from RAPID to RAPID-WATCH funding marked significant changes to the RAPID WAVE observational system. Line B was abandoned and a joint array with BIO, known as the RAPID Scotia Line, to the south west was developed. This line receives annual servicing by BIO, with cruise participation from the RAPID WAVE team.
The servicing of RAPID WAVE BPRs on Line W remained a biennial activity during the RAPID and RAPID-WATCH programmes.
A small number of BPR deployments have also taken place off the coast of Spain as part of the RAPIDO element of RAPID WAVE.
Instrumentation
Types of instruments and measurements:
- Moored BPRs
- Moored CTD/CT loggers
- Moored current meters (RAPID-WATCH)
- Moored ADCPs (RAPID-WATCH)
- Shipboard measurements: CTD, underway, salinity, LADCP, ADCP
Contacts
Collaborator | Organisation | Project |
---|---|---|
Prof. Chris M. Hughes | National Oceanography Centre, U.K | RAPID WAVE |
Dr. Miguel Angel Morales Maqueda | National Oceanography Centre, U.K | RAPID WAVE |
Dr. Shane Elipot | National Oceanography Centre, U.K | RAPID WAVE |
Dr. John M. Toole | Woods Hole Oceanographic Institution, U.S | Line W |
Dr. Igor Yashayaev | Bedford Institute of Oceanography, Canada | - |
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.
Scientific Objectives
- 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.
Projects
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.
Data Activity or Cruise Information
Cruise
Cruise Name | OC421 |
Departure Date | 2006-04-05 |
Arrival Date | 2006-04-15 |
Principal Scientist(s) | John M Toole (Woods Hole Oceanographic Institution Department of Physical Oceanography) |
Ship | RV Oceanus |
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 |