Metadata Report for BODC Series Reference Number 1115384
Metadata Summary
Problem Reports
Data Access Policy
Narrative Documents
Project Information
Data Activity or Cruise Information
Fixed Station Information
BODC Quality Flags
Metadata Summary
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Problem Reports
No Problem Report Found in the Database
RAPID Cruise D324 Sea Surface Hydrography Data Quality Notes
Hydrography data have been flagged between 14:49 12/10/2007 and 20:05 14/10/2007. During this period Discovery was moored in Tenerife and some of the data collected by the surfmet system may be unrealistic.
Users should be aware that the beam attenuation channel appears suspect for much of the series.There are lots of very low values present and occasions where steps can be seen in the data. Additionally. the trends in the data bear little relation to those seen in the chlorophyll channel. Obvious spikes have been flagged suspect but the whole channel should be regarded as suspect.
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
Falmouth Scientific Inc. OEM CT sensor
The OEM CT sensor is designed to provide high accuracy conductivity and temperature measurements in a package that can be readily integrated into user systems. The CT sensor relies on an inductively coupled conductivity sensor, with a large inside diameter that eliminates the need for pumps. A high grade Platinum Resistance Thermometer is used to measure temperature.
Sensor specifications are given in the table below. Since 2009 this instrument has been manufactured by Teledyne RD Instruments as a Citadel CT-EK Sensor. More information about the instrument can be found on the Teledyne Citadel specification sheet.
Sensor Specifications
| Instrument Parameter | Small CT Cell Conductivity | Large CT Cell Conductivity | Temperature | |
|---|---|---|---|---|
| Range | 0 to 70 mS cm-1 | 0 to 70 mS cm-1 | -2 to 35 degrees C | |
| Accuracy | ±0.020 mS cm-1 | ±0.010 mS cm-1 | ±0.050 degrees C | |
| Stability | ±0.005 mS cm-1 mo-1 | ±0.003 mS cm-1 | ±0.005 degrees C mo-1 | |
| Response | 20 cm @ 1 m s-1 | 15 cm @ 1 m s-1 | 20 seconds internal, 1 second external |
| Power Input | 50 mW @ 6 VDC, voltage range 6 - 14 VDC |
|---|---|
| Logic | 2 0 - 5 VDC control lines |
| Output Impedance | 500 ohms |
WET Labs WETStar Fluorometers
WET Labs WETStar fluorometers are miniature flow-through fluorometers, designed to measure relative concentrations of chlorophyll, CDOM, uranine, rhodamineWT dye, or phycoerythrin pigment in a sample of water. The sample is pumped through a quartz tube, and excited by a light source tuned to the fluorescence characteristics of the object substance. A photodiode detector measures the portion of the excitation energy that is emitted as fluorescence.
Specifications
By model:
| Chlorophyll WETStar | CDOM WETStar | Uranine WETStar | Rhodamine WETStar | Phycoerythrin WETStar | |
|---|---|---|---|---|---|
| Excitation wavelength | 460 nm | 370 nm | 485 nm | 470 nm | 525 nm |
| Emission wavelength | 695 nm | 460 nm | 530 nm | 590 nm | 575 nm |
| Sensitivity | 0.03 µg l-1 | 0.100 ppb QSD | 1 µg l-1 | - | - |
| Range | 0.03-75 µg l-1 | 0-100 ppb; 0-250 ppb | 0-4000 µg l-1 | - | - |
All models:
| Temperature range | 0-30°C |
|---|---|
| Depth rating | 600 m |
| Response time | 0.17 s analogue; 0.125 s digital |
| Output | 0-5 VDC analogue; 0-4095 counts digital |
Further details can be found in the manufacturer's specification sheet, and in the instrument manual.
WETLabs C-Star transmissometer
This instrument is designed to measure beam transmittance by submersion or with an optional flow tube for pumped applications. It can be used in profiles, moorings or as part of an underway system.
Two models are available, a 25 cm pathlength, which can be built in aluminum or co-polymer, and a 10 cm pathlength with a plastic housing. Both have an analog output, but a digital model is also available.
This instrument has been updated to provide a high resolution RS232 data output, while maintaining the same design and characteristics.
Specifications
| Pathlength | 10 or 25 cm |
| Wavelength | 370, 470, 530 or 660 nm |
| Bandwidth | ~ 20 nm for wavelengths of 470, 530 and 660 nm ~ 10 to 12 nm for a wavelength of 370 nm |
| Temperature error | 0.02 % full scale °C-1 |
| Temperature range | 0 to 30°C |
| Rated depth | 600 m (plastic housing) 6000 m (aluminum housing) |
Further details are available in the manufacturer's specification sheet or user guide.
RAPID Cruise D324 Sea Surface Hydrography Instrumentation
| Sensor | Serial number | Last calibration date |
|---|---|---|
| FSI OCM housing conductivity sensor | 1376 | Not calibrated |
| FSI OTM housing temperature sensor | 1374 | 02/05/2007 |
| FSI OTM remote temperature sensor | 1401 | 01/09/2004 |
| Wetlabs C-star transmissometer | CST-114R | June 2007 |
| Wetlabs fluorometer | WS3S-246 | June 2007 |
Seawater was continually pumped from the hull of the ship (at a depth of about 5 m) through the various underway sensors on-deck (known as ship's non-toxic supply). An outlet from this, situated in the ship's wet laboratory, was used to collect the calibration samples for the underway sensors.
RAPID Cruise D324 Sea Surface Hydrography Data Processing
Data Processing Procedures
Originator's processing
Data from the surfmet system were transferred daily from the ship's computer system and calibrated to give along track surface properties such as sea surface temperature. Four executable programs were run daily to process the data. The first program transferred the data from RVS to PSTAR format, while subsequent programs calculated salinity.
Further information on originator's processing can be obtained in the D324 cruise report.
BODC processing
The data were transferred from PSTAR format into BODC internal format (a netCDF subset) to allow use of the in-house visualisation tool (EDSERPLO). Reformatting and data calibration was carried out, and is discussed in the individual instrument sections below. The following table shows the mapping of variables from the originator's files to standardised BODC parameters, along with unit conversions where applicable.
| Parameter | Units | BODC Parameter code | Units | Comments |
|---|---|---|---|---|
| Latitude | ° (+ve N) | ALATGP01 | ° (+ve N) | - |
| Longitude | ° (+ve E) | ALONGP01 | ° (+ve E) | - |
| Attenuance | Volts | ATTNUN25 | m-1 | Generated at BODC |
| Conductivity | mmho/cm | CNDCSG01 | Sm-1 | Unit conversion: /10. Channel dropped from final series. |
| Chlorophyll-a concentration | CPHLUMTF | mg m-3 | Generated at BODC | |
| Fluorescence | FVLTWS01 | Volts | Channel dropped from final series. | |
| Salinity | PSALSG01 | dimensionless | Calibrated against discrete sample data by originator's | |
| Sea surface temperature | °C | TEMPHG01 | °C | Calibrated against surface CTD data at BODC |
| Temperature of conductivity measurement | °C | TMESSG01 | °C | Channel dropped from final series. |
| Transmissometer voltage | Volts | TVLTDZ01 | Volts | Channel dropped from final series. |
-
Salinity
Salinity data were calibrated at BODC, with discrete TSG samples collected during the cruise, using linear correction. 49 data points were used to derive a constant offset correction, which was applied to the data from 11:35 05/10/2007 until 14:00 30/10/2007 of the form:
Strue = Smeasured -0.16935.
A linear correction was then derived using 32 data points and was applied to the data from 14:00 30/10/2007 until 19:22 08/11/2007 of the form:
Strue = 0.68069 x Smeasured + 12.0156 with an r2 value of 86.2%.
-
Temperature
The hull temperature data were verified at BODC using CTD temperature data. Note, the CTD measurements have not been verified against an independent source. The offset (Underway temperature- CTD temperature) was examined to see if it varied with time or temperature. Outliers, with high standard deviations, were identified and discarded.
No significant correlation was established between offset and CTD temperature or time. The mean offset of the data is +0.0067. This is within the stated accuracy of the sensor and therefore no adjustment to the temperature data is required.
-
Beam attenuation
Raw transmissometer data were converted to beam attenuance using manufacturer's coefficients in the formulae:
c = -1/0.25 x ln(Tr)
where
Tr = (Vsig-0.060)/(4.653-0.060)
-
Fluorescence
Fluorescence data were converted from raw voltages using manufacturer's coefficients in the formulae:
CHL (µg/l) = 15.1 x (Output - 0.080)
References
Cunningham, S.A. and et al, .Rayner, D. (ed.) (2008) RRS Discovery Cruise D324, 06 Oct-09 Nov 2007. RAPID Mooring Cruise Report. Southampton, UK, National Oceanography Centre Southampton, 141pp. (National Oceanography Centre Southampton Cruise Report, 34)
Project Information
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.
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)
Data Activity or Cruise Information
Cruise
| Cruise Name | D324 |
| Departure Date | 2007-10-06 |
| Arrival Date | 2007-11-09 |
| Principal Scientist(s) | Stuart A Cunningham (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 |
