Metadata Report for BODC Series Reference Number 1081214
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 Quality Report
Secondary Fluorometer (WETLabs)
The data originator considers the data from the secondary fluorometer to be bad throughout the whole profile for casts 2 to 14, inclusive. These data have been flagged suspect. In addition, BODC has flagged the data in cast 1 as suspect since the profile does not agree well with the data from the primary fluorometer.
Irradiance
The data originator considers the irradiance data from casts 2 to 12, inclusive, to be bad throughout the profile. These data have been flagged suspect.
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
LI-COR LI-193 Spherical Quantum Sensor
The LI-193 Underwater Spherical Quantum Sensor measures irradiance over the photosynthetically active radiation (PAR) spectral range (400-700 nm). The instrument measures photon flux from all directions, which is often termed photosynthetic photon flux fluence rate (PPFFR) or quantum scalar irradiance. This measurement is particularly important when studying phytoplankton, which utilize radiation from all directions for photosynthesis.
The LI-193 can operate down to 350 m and is fitted with a blue-enhanced silicon photovoltaic detector. Two versions of the instrument are available (193SA and 193SB). These use different connector types for the underwater cable, but the sensors operate in the same manner.
Sensor Specifications
| Absolute Calibration | ± 5 % in air traceable to NBS. |
|---|---|
| Sensitivity | Typically 7 µA per 1000 µmol s-1 m-2 |
| Linearity | Maximum deviation of 1 % up to 10,000 µmol s-1 m-2. |
| Stability | < ± 2 % change over a 1 year period. |
| Response Time | 10 µs. |
| Temperature Dependence | ± 0.15 % per °C maximum. |
| Angular Response | < ± 4% error up to ± 90° from normal axis. |
| Azimuth | < ± 3 % error over 360 ° at 90 ° from normal axis. |
| Detector | High stability silicon photovoltaic detector (blue enhanced). |
| Sensor Housing | Corrosion resistant metal with acrylic diffuser for both saltwater and freshwater applications with an injection moulded, impact resistant, acrylic diffuser. Units have been tested to 500 psi (3400 kPa) (350 meters). |
| Weights | 142 g |
| Cable | Requires 2222UWB Underwater Cable |
Further information can be found in the manufacturer's specification sheet and instruction manual.
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.
HUD08037 Leg1 CTD Instrumentation
CTD unit and auxiliary sensors
The CTD system used on cruise HUD08037 Leg1 was the Sea-Bird 9 plus. The header information in the original CTD data files indicates that the CTD was fitted with the following scientific sensors:
| Sensor | Serial Number | Last calibration date |
|---|---|---|
| Primary Temperature Sensor | 032298 | 16 January 2008 |
| Primary Conductivity Sensor | 1873 | 16 January 2008 |
| Pressure-Digiquartz | 69009 | 25 February 2008 |
| Secondary Temperature Sensor | 031423 | 22 January 2008 |
| Secondary Conductivity Sensor | 1125 | 22 January 2008 |
| Primary Sea-Bird SBE 43 oxygen sensor | 430042 | 10 February 1997 |
| Secondary Sea-Bird SBE 43 oxygen sensor | 430133 | 21 January 2006 |
| Chelsea Aquatracka Mk III (chlorophyll a) fluorometer | 088172 | 10 February 1997 |
| Wetlabs Fluorometer | WSCD-987P | 18 August 2003 |
| Licor 193SA PAR sensor | SPQA2711-LI-193SA | 17 June 1999 |
| SBE35 Temperature Sensor | unknown | unknown |
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.
Chelsea Technologies Group Aquatracka MKIII fluorometer
The Chelsea Technologies Group Aquatracka MKIII is a logarithmic response fluorometer. Filters are available to enable the instrument to measure chlorophyll, rhodamine, fluorescein and turbidity.
It uses a pulsed (5.5 Hz) xenon light source discharging along two signal paths to eliminate variations in the flashlamp intensity. The reference path measures the intensity of the light source whilst the signal path measures the intensity of the light emitted from the specimen under test. The reference signal and the emitted light signals are then applied to a ratiometric circuit. In this circuit, the ratio of returned signal to reference signal is computed and scaled logarithmically to achieve a wide dynamic range. The logarithmic conversion accuracy is maintained at better than one percent of the reading over the full output range of the instrument.
Two variants of the instrument are available, both manufactured in titanium, capable of operating in depths from shallow water down to 2000 m and 6000 m respectively. The optical characteristics of the instrument in its different detection modes are visible below:
| Excitation | Chlorophyll a | Rhodamine | Fluorescein | Turbidity |
|---|---|---|---|---|
| Wavelength (nm) | 430 | 500 | 485 | 440* |
| Bandwidth (nm) | 105 | 70 | 22 | 80* |
| Emission | Chlorophyll a | Rhodamine | Fluorescein | Turbidity |
| Wavelength (nm) | 685 | 590 | 530 | 440* |
| Bandwidth (nm) | 30 | 45 | 30 | 80* |
* The wavelengths for the turbidity filters are customer selectable but must be in the range 400 to 700 nm. The same wavelength is used in the excitation path and the emission path.
The instrument measures chlorophyll a, rhodamine and fluorescein with a concentration range of 0.01 µg l-1 to 100 µg l-1. The concentration range for turbidity is 0.01 to 100 FTU (other wavelengths are available on request).
The instrument accuracy is ± 0.02 µg l-1 (or ± 3% of the reading, whichever is greater) for chlorophyll a, rhodamine and fluorescein. The accuracy for turbidity, over a 0 - 10 FTU range, is ± 0.02 FTU (or ± 3% of the reading, whichever is greater).
Further details are available from the Aquatracka MKIII specification sheet.
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.
HUD08037 Leg1 CTD Originator Processing
Sampling Strategy
A total of 12 CTD casts were performed during cruise HUD08037 Leg1. Niskin bottles were attached to the CTD frame and used to collect water samples at selected depths on stations throughout the cruise. Nine of these casts were performed at the RAPID mooring sites and, consequently, data from these stations were incorporated into the UK RAPID WAVE dataset.
Data Processing
Following the completion of each CTD cast the data were processed using SBE Seasave v7.14c software.
The WILDEDIT program was run to remove any large pressure spikes and FILTER was run on the pressure channel. The program ALIGNCTD was run to advance the oxygen measurements by 8 seconds and regress conductivity measurements by 0.01 seconds. CELLTM was then run on the data, followed by DERIVE to produce salinity data, SPLIT, LOOPEDIT (which was run with a minimum CTD velocity of 0.05 m/s), WILDEDIT and BINAVG to produce 1db bin averaged .ODF files.
Calibrations
Oxygen values were calibrated by the data originator by adding a polynomial function of pressure, oxygen and temperature to its values at all pressure levels.
Discrete salinity data from each leg of the cruise were used by the data originator to calibrate CTD salinity data. Salinity samples taken from the CTD bottles were merged with reprocessed CTD data at bottle trip depths with the data originator running a script to determine the required corrections for CTD conductivity and salinity channels. Due to a significant drop in water sample data quality between the first and second legs of the cruise, casts contributing to the RAPID WAVE dataset were calibrated independently from non-RAPID data. These corrections were applied to data in the relevant .ODF files, with additional corrections being applied by adding a polynomial function of pressure at all pressure levels.
References
Cruise Report for The Hudson Mission HUD 2008-037
HUD08037 Leg1 CTD Processing undertaken by BODC
19 CTD casts spanning all three legs of the cruise were submitted to BODC for inclusion in the RAPID WAVE dataset. These were supplied as 38 .ODF files containing 1 db bin averaged data, split into up and down profiles for each cast. In total, nine of the casts were from the first leg of the cruise.
The downcasts were reformatted to BODC's internal (.qxf) format, a subset of NetCDF. The data originator reported no difference in data quality between primary and secondary conductivity data, but secondary oxygen sensor data were preferred. Data from the secondary sensors were therefore preferentially retained in the BODC banked dataset and the primary temperature, salinity and oxygen channels were dropped.
The following table shows the mapping of variables within the originator ASCII files to appropriate BODC parameter codes for channels contained in the RAPID WAVE banked series.
| Originator's Variable | Units | BODC Parameter Code | Units | Comments |
|---|---|---|---|---|
| PRES_01 | dbar | PRESPR01 | dbar | - |
| TEMP_02 | °C | TEMPCC01 | °C | Checked against data from SBE35. It should be noted that temperature was recorded on the ITS-68 scale. |
| PSAL_02 | - | PSALCC01 | - | Calibrated by data originator using discrete water samples from the CTD bottles. |
| FC_01 | ug l-1 | CPHLPM01 | mg m-3 | - |
| FWETLABS_01 | mg m-3 | CPHLPM02 | mg m-3 | - |
| DOXY_02 | ml l-1 | DOXYSU01 | µmol l-1 | Data converted from ml l-1 to µmol l-1 by multiplying by 44.658 |
| PSAR_01 | MicroEinsteins per square metre per second | SCIRR4PI | MicroEinsteins per square metre per second | - |
| - | - | POTMCV01 | °C | Channel derived at BODC |
| - | - | SIGTPR01 | kg m-3 | Channel derived at BODC |
The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, and missing data marked by both setting the data to an appropriate value and setting the quality control flag.
Project Information
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- 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 | HUD08037 Leg1 |
| Departure Date | 2008-09-28 |
| Arrival Date | 2008-10-06 |
| Principal Scientist(s) | Erica J Head (Bedford Institute of Oceanography) |
| Ship | CCGS Hudson |
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 |
