Metadata Report for BODC Series Reference Number 771948
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
The quality of measurements obtained with the Satlantic ISUS UV in-situ nitrate sensor were considered highly unreliable by the data originators and it was suggested that these data should be dropped from the series. It was confirmed that these data were questionable following in-house screening at BODC. Since the data were not fit for future purpose the channel was deleted from the series.
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
Satlantic and MBARI In Situ Ultraviolet Spectrophotometer ISUS, ISUS V2 and ISUS V3
The ISUS series of instruments are submersible sensors that use ultraviolet absorption spectroscopy to measure in situ dissolved chemical species. Absorption spectra are measured by illuminating a sample of seawater with UV light and analysing the signal with a UV spectrometer. The calibration process embedded in the system creates a library of absorption spectra for the main absorbing species in this region of the spectrum. An optimization process adjusts the concentrations of the calibrated species spectra until the computed spectrum matches the measured one.
The original ISUS was developed by the Monterey Bay Aquarium Research Institute (MBARI) as a means of measuring nitrate, bromide and bisulfide in the ocean using in situ ultraviolet spectrometry, as described in Johnson and Coletti (2002). This prototype was superseded by the commercially available Satlantic MBARI-ISUS V2, which was developed jointly by MBARI and Satlantic, and was specifically designed to measure nitrate concentrations. The latest version is the Satlantic ISUS V3, which is also designed for nitrate measurements.
The ISUS V2 provides multiple interfaces and the data can be output in analog (for easy interface with CTD systems), digital telemetry (concentration only; the full spectral output is in ASCII or binary) or digital (stored on an internal flash card) format. This instrument can be powered internally or from external sources. The ISUS V3 has full USB capability and a Windows-based program to download files, setup schedules, log and view data. Specifications for the V2 and V3 are presented below and are the same for both models, unless otherwise stated.
Specifications
| Resolution | ± 0.05 µM |
| Accuracy | V2: ± 2 µM or 2% of reading, whichever is larger V3: ± 2 µM (0.028 mg l-1) or 10% of reading, whichever is larger |
| Range | V2: up to 2000 µM V3: 0.5 to 2000 µM (0.007 to 28 mg l-1) |
| Sample rate | 1 Hz |
| Depth rating | 1000 m (200 m optional for V3 only) |
| Operating temperature | V2: 0 to 35°C V3: 0 to 40°C |
| Path length | 1 cm |
| Wavelength range | 200 to 400 nm |
| Lamp type | Deuterium |
| Lamp life time | V2: 1000 hours to 50% intensity at 240 nm V3: 900 hours |
| Thermal compensation | 0 to 40°C (V3 only) |
| Salinity compensation | 0 to 40 psu (V3 only) |
References
Johnson, K.S. and Coletti, L.J., 2002. In situ ultraviolet spectrophotometry for high resolution and long-term monitoring of nitrate, bromide and bisulfide in the ocean. Deep-Sea Research I, 49, 1291-1305.
Further information can be found in the manual for the ISUS V2 and the manufacturer's specification sheet for theISUS V3.
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.
Benthos Programmable Sonar Altimeter (PSA) 916 and 916T
The PSA 916 is a submersible altimeter that uses the travel time of an acoustic signal to determine the distance of the instrument from a target surface. It provides the user with high resolution altitude or range data while simultaneously outputting data through a digital serial port. A wide beam angle provides for reliable and accurate range measurements under the most severe operational conditions. The instrument is electronically isolated to eliminate any potential signal interference with host instrument sensors. The PSA 916 is an upgrade of the PSA 900.
The standard model (PSA 916) has an operational depth range of 0 - 6000 m, while the titanium PSA 916T has a depth range of 0 - 10000 m. All other specifications for the two versions are the same.
Specifications
| Transmit frequency | 200 kHz |
| Transmit pulse width | 250 µs |
| Beam pattern | 14° conical |
| Pulse repetition rate | internal selection: 5 pps external selection: up to 5 pps- user controlled |
| Range | 100 m full scale 1.0 m guaranteed minimum 0.8 m typical |
| Range | 1 cm for RS232 output 2.5 cm for analog output |
| Operating depth | 6000 m (PSA 916) or 10000 m (PSA 916T) |
Further details can be found in the manufacturer's specification sheets for the PSA 916 and the PSA 916T.
Instrument Description
CTD Stainless Steel Unit and Auxiliary Sensors
| Instrument/Sensor | Serial Number | Manufacturer's Calibration Date | Comments |
|---|---|---|---|
| Sea-Bird 911plus CTD | 0636 | ||
| Sea-Bird SBE 9plus Digiquartz primary pressure sensor | 83008 | 13 May 2005 | |
| Sea-Bird SBE 3 primary1 temperature sensor | 4383 | 1 May 2007 | Vane-mounted |
| Sea-Bird SBE 3 secondary1 temperature sensor | 4782 | 12 April 2007 | CTD-mounted |
| Sea-Bird SBE 4 primary1 conductivity sensor | 2164 | 1 May 2007 | Vane-mounted |
| Sea-Bird SBE 4 secondary1 conductivity sensor | 3258 | 27 March 2007 | CTD-mounted |
| Sea-Bird SBE 43 oxygen sensor | 0619 | 5 October 2006 | |
| Benthos PSA-916T altimeter | 1040 | repaired December 2006 | |
| Chelsea Aquatracka Mk III (chlorophyll a) fluorimeter | 088095 | 4 January 2007 | |
| Chelsea Alphatracka Mk II (25cm, 660 nm) transmissometer | 161-2642-002 | 4 September 1996 | |
| 2π PML (Chelsea) PAR sensor (down-welling) | 09 | 23 March 2005 | removed from casts greater than 1000 m |
| Satlantic ISUS nitrate sensor | 60 | removed from casts greater than 1000 m 25 July 2007 (Laboratory calibration) | |
| Sea-Bird SBE 32 carousel | 32-37898-0518 | ||
| Ocean Test Equipment water bottles (20 L) | 32-37898-0518 | positions 1-24 | |
| RDI Workhorse Monitor 300 kHz ADCP (master) | 5415 | ||
| RDI Workhorse Monitor 300 kHz ADCP (slave) | 9414 |
1The primary temperature and conductivity sensor pair (described here) are referred to as secondary sensors in all files produced from Sea-Bird Software processing. The names were swapped during NOCS PSTAR processing where the Sea-Bird named, secondary sensors became the primary sensor pair.
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.
Aquatracka fluorometer
The Chelsea Instruments Aquatracka is a logarithmic response fluorometer. It uses a pulsed (5.5 Hz) xenon light source discharging between 320 and 800 nm through a blue filter with a peak transmission of 420 nm and a bandwidth at half maximum of 100 nm. A red filter with sharp cut off, 10% transmission at 664 nm and 678 nm, is used to pass chlorophyll-a fluorescence to the sample photodiode.
The instrument may be deployed either in a through-flow tank, on a CTD frame or moored with a data logging package.
Further details can be found in the manufacturer's specification sheet.
Chelsea Technologies Group ALPHAtracka and ALPHAtracka II transmissometers
The Chelsea Technologies Group ALPHAtracka (the Mark I) and its successor, the ALPHAtracka II (the Mark II), are both accurate (< 0.3 % fullscale) transmissometers that measure the beam attenuation coefficient at 660 nm. Green (565 nm), yellow (590 nm) and blue (470 nm) wavelength variants are available on special order.
The instrument consists of a Transmitter/Reference Assembly and a Detector Assembly aligned and spaced apart by an open support frame. The housing and frame are both manufactured in titanium and are pressure rated to 6000 m depth.
The Transmitter/Reference housing is sealed by an end cap. Inside the housing an LED light source emits a collimated beam through a sealed window. The Detector housing is also sealed by an end cap. A signal photodiode is placed behind a sealed window to receive the collimated beam from the Transmitter.
The primary difference between the ALPHAtracka and ALPHAtracka II is that the Alphatracka II is implemented with surface-mount technology; this has enabled a much smaller diameter pressure housing to be used while retaining exactly the same optical train as in the Mark I. Data from the Mark II version are thus fully compatible with that already obtained with the Mark I. The performance of the Mark II is further enhanced by two electronic developments from Chelsea Technologies Group - firstly, all items are locked in a signal nulling loop of near infinite gain and, secondly, the signal output linearity is inherently defined by digital circuitry only.
Among other advantages noted above, these features ensure that the optical intensity of the Mark II, indicated by the output voltage, is accurately represented by a straight line interpolation between a reading near full-scale under known conditions and a zero reading when blanked off.
For optimum measurements in a wide range of environmental conditions, the Mark I and Mark II are available in 5 cm, 10 cm and 25 cm path length versions. Output is default factory set to 2.5 volts but can be adjusted to 5 volts on request.
Further details about the Mark II instrument are available from the Chelsea Technologies Group ALPHAtrackaII specification sheet.
Chelsea Technologies Photosynthetically Active Radiation (PAR) Irradiance Sensor
This sensor was originally designed to assist the study of marine photosynthesis. With the use of logarithmic amplication, the sensor covers a range of 6 orders of magnitude, which avoids setting up the sensor range for the expected signal level for different ambient conditions.
The sensor consists of a hollow PTFE 2-pi collector supported by a clear acetal dome diverting light to a filter and photodiode from which a cosine response is obtained. The sensor can be used in moorings, profiling or deployed in towed vehicles and can measure both upwelling and downwelling light.
Specifications
| Operation depth | 1000 m |
| Range | 2000 to 0.002 µE m-2 s-1 |
| Angular Detection Range | ± 130° from normal incidence |
| Relative Spectral Sensitivity | flat to ± 3% from 450 to 700 nm down 8% of 400 nm and 36% at 350 nm |
Further details can be found in the manufacturer's specification sheet.
BODC Processing
The data arrived at BODC in PSTAR format files representing all of the stainless steel CTD casts taken during the cruise. These were reformatted to the internal NetCDF format using standard BODC data banking procedures. The following table shows how the variables within the .2db files were mapped to appropriate BODC parameter codes:
| Originator's Variable | Units | Description | BODC Parameter Code | Units | Comment |
|---|---|---|---|---|---|
| press | decibar | Pressure (spatial co-ordinate) exerted by the water column | PRESPR01 | decibar | |
| temp | deg C | Temperature (ITS-90) of the water column (primary sensor) | TEMPS901 | deg C | |
| cond | mS cm-1 | Conductivity of the water column (primary sensor) | CNDCST01 | S m-1 | Conductivity ÷ 10 |
| temp2 | deg C | Temperature (ITS-90) of the water column (secondary sensor) | TEMPS902 | deg C | |
| cond2 | mS cm-1 | Conductivity of the water column (secondary sensor) | CNDCST02 | S m-1 | Conductivity ÷ 10 |
| alt | m | Height above seabed in the water column | AHSFZZ01 | m | |
| oxygen | µmol Kg-1 | Calibrated (independent samples) dissolved oxygen concentration measured with Sea-Bird SBE 43 sensor | DOXYSC01 | µmol L-1 | |
| t2-t1 | deg C | Temperature difference between sensors (temp2 - temp) | Not transferred - not environmental measurement | ||
| c2-c1 | deg C | Conductivity difference between sensors (cond2 - cond) | Not transferred - not environmental measurement | ||
| ptemp | deg C | Temperature of CTD internal electronics | Not transferred - not environmental measurement | ||
| fluor | µg L-1 | Calibrated (manufacturer) concentration of chlorophyll a by in-situ fluorimeter | CPHLPM01 | mg m-3 | µg L-1 = mg m3 |
| nitrate | µmol | Calibrated (laboratory) concentration of dissolved nitrate by in-situ UV sensor | Dropped due to unreliability | ||
| trans | % | Transmittance of the water column by transmissometer | POPTDR01 | % | |
| lat | deg | Latitude north by GPS receiver | Not transferred | ||
| lon | deg | Longitude east by GPS receiver | Not transferred | ||
| PAR | W m-2 | Photosynthetically active radiation in the water column (down-welling) by 2π radiometer | DWIRPP01 | W m-2 | |
| UPAR | W m-2 | Photosynthetically active radiation in the water column (up-welling) by 2π radiometer | UWIRPP01 | W m-2 | In-house screening showed sensor was not present on CTD, therefore channel was deleted |
| flag | None | Not transferred - unknown flag channel | |||
| salin | psu | Calibrated (independent samples) salinity of the water column (primary) | PSALCC01 | psu | Derived from pressure, primary temperature and conductivity |
| salin2 | psu | Calibrated (independent samples) salinity of the water column (secondary) | PSALCC02 | psu | Derived from pressure, secondary temperature and conductivity |
| potemp | deg C | Potential temperature with respect to the surface (primary) | Not transferred - derived | ||
| potemp2 | deg C | Potential temperature with respect to the surface (secondary) | Not transferred - derived | ||
| sigma0 | kg m-3 | Potential density with respect to the surface | Not transferred - calculated at BODC | ||
| sigma2 | kg m-3 | Potential density with respect to 2000 m | Not transferred - derived |
Four new channels were generated from the originator's parameters during transfer and are described below:
| BODC Parameter Code | Units | Description | Comment |
|---|---|---|---|
| OXYSSC01 | % | Saturation of oxygen {O2} in the water column [dissolved phase] by Sea-Bird SBE 43 sensor and calibration against sample data and computation from concentration using Benson and Krause algorithm2 | |
| SIGTPR01 | Kg m-3 | Sigma-theta of the water column by CTD and computation from salinity and potential temperature using UNESCO algorithm1 | Computed from pressure, primary potential temperature and primary salinity |
| SIGTPR02 | Kg m-3 | Sigma-theta of the water column by CTD and computation from salinity and potential temperature using UNESCO algorithm1 | Computed from pressure, secondary potential temperature and secondary salinity |
| TOKGPR01 | L Kg-1 | Conversion factor (volume to mass) for the water column by CTD and computation of density reciprocal from pressure, primary temperature and primary salinity |
The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, missing data by both setting the data to an appropriate value and setting the quality control flag.
References
1Fofonoff N.P. and Millard R.C., Jr. (1983). Algorithms for computations of fundemental properties of seawater. UNESCO Technical Papers in Marine Science No. 44., 53pp.
2Benson, B.B. and Krause D., Jr. (1984). The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere. Limnology and Oceanography, 29:620-632.
Originator's Data Processing
Sampling Strategy
A total of 84 CTD stations1 were carried out during the cruise in the areas of the Extended Ellett Line and Icelandic Basin. From these, a total of 92 CTD downcast profiles of 2 decibar data were collected2, of which, 75 profiles were obtained using the instruments associated to the stainless steel CTD. Using this unit, 21 profiles of data were collected as part of CTD survey 1 (C1), 3 as part of CTD survey 2 (C2), 16 as part of SeaSoar survey 1 (S1), 30 as part of SeaSoar survey 2 (S2) and 6 profiles of data were collected in the area of the Extended Ellett Line. General information regarding CTD sampling strategy can be found in the cruise report from p137.
1Please note that a total of 84 CTD 'profiles' were reported to have been carried out during the cruise on p137 of the cruise report, however, this actually refers to the number of CTD stations visited during the cruise.
2Please note that the collection of 94 profiles was attempted during the cruise but data were corrupted from cast 16220A and the CTD malfunctioned during cast 16295A. Therefore, only 92 profiles of data were collected.
Data Processing
Raw CTD files were initially processed through Sea-Bird software (SBEDataProcessing-Win32) using a modified protocol from Discovery cruise D306. The resulting files were then processed through NOCS Unix scripts into PSTAR format using slightly modified versions of execs used on cruise D306. Separate NOCS Unix scripts were used for stainless steel unit casts and titanium unit casts. Full processing details can be found in the cruise report from p138.
Field Calibrations
CTD salinity and oxygen were calibrated following the protocol described for salinity in the cruise report (p149, p150-151). Values obtained from the stainless steel CTD were calibrated using independent salinity and oxygen bottles samples, collected via the unit's OTE bottle rosette. Bottle samples were determined using an autosalinometer for salinity and the Winkler titration for oxygen. Further information regarding the collection and measurement of bottle samples can be found in the cruise report from p172 for salinity and p198 for oxygen. Prior to calibration, data points outside 2 standard deviation's of the mean offset (bottle value minus CTD value) were removed. The mean offset was found to vary for different periods of the cruise. Therefore, the cruise was split into two periods of calibration for salinity and three periods for oxygen. These were pre- and post-station 16224 for salinity and stations 16195-16202, 16203-16240 and 16243-16287 for oxygen. Due to time constraints, not all of the independent bottle samples had been processed at the time of writing the cruise report and revised calibrations are as below:
Stainless steel CTD
- Salinity (primary sensor)
- calibrated salinity = (-0.0752 + 1.0022) multiplied by raw (for casts 16195A to 16222A)
calibrated salinity = (0.3462 + 0.9904) multiplied by raw (for casts 16224A to 16287A)
where 'raw' is CTD primary salinity
- Salinity (secondary sensor)
- calibrated salinity = (-0.1914 + 1.0056) multiplied by raw (for casts 16195A to 16222A)
calibrated salinity = (0.2754 + 0.9926) multiplied by raw (for casts 16224A to 16287A)
where 'raw' is CTD secondary salinity
- Oxygen
- calibrated = (-13.0507 + 1.1583) multiplied by raw (for casts 16195A to 16202A)
calibrated oxygen = (-12.4329 + 1.1370) multiplied by raw (for casts 16203A to 16240A)
calibrated oxygen = (-8.6379 + 1.1346) multiplied by raw (for casts 16243A to 16287A)
where 'raw' is CTD oxygen
Project Information
Oceans 2025 - The NERC Marine Centres' Strategic Research Programme 2007-2012
Who funds the programme?
The Natural Environment Research Council (NERC) funds the Oceans 2025 programme, which was originally planned in the context of NERC's 2002-2007 strategy and later realigned to NERC's subsequent strategy (Next Generation Science for Planet Earth; NERC 2007).
Who is involved in the programme?
The Oceans 2025 programme was designed by and is to be implemented through seven leading UK marine centres. The marine centres work together in coordination and are also supported by cooperation and input from government bodies, universities and other partners. The seven marine centres are:
- National Oceanography Centre, Southampton (NOCS)
- Plymouth Marine Laboratory (PML)
- Marine Biological Association (MBA)
- Sir Alister Hardy Foundation for Marine Science (SAHFOS)
- Proudman Oceanographic Laboratory (POL)
- Scottish Association for Marine Science (SAMS)
- Sea Mammal Research Unit (SMRU)
Oceans2025 provides funding to three national marine facilities, which provide services to the wider UK marine community, in addition to the Oceans 2025 community. These facilities are:
- British Oceanographic Data Centre (BODC), hosted at POL
- Permanent Service for Mean Sea Level (PSMSL), hosted at POL
- Culture Collection of Algae and Protozoa (CCAP), hosted at SAMS
The NERC-run Strategic Ocean Funding Initiative (SOFI) provides additional support to the programme by funding additional research projects and studentships that closely complement the Oceans 2025 programme, primarily through universities.
What is the programme about?
Oceans 2025 sets out to address some key challenges that face the UK as a result of a changing marine environment. The research funded through the programme sets out to increase understanding of the size, nature and impacts of these changes, with the aim to:
- improve knowledge of how the seas behave, not just now but in the future;
- help assess what that might mean for the Earth system and for society;
- assist in developing sustainable solutions for the management of marine resources for future generations;
- enhance the research capabilities and facilities available for UK marine science.
In order to address these aims there are nine science themes supported by the Oceans 2025 programme:
- Climate, circulation and sea level (Theme 1)
- Marine biogeochemical cycles (Theme 2)
- Shelf and coastal processes (Theme 3)
- Biodiversity and ecosystem functioning (Theme 4)
- Continental margins and deep ocean (Theme 5)
- Sustainable marine resources (Theme 6)
- Technology development (Theme 8)
- Next generation ocean prediction (Theme 9)
- Integration of sustained observations in the marine environment (Theme 10)
In the original programme proposal there was a theme on health and human impacts (Theme 7). The elements of this Theme have subsequently been included in Themes 3 and 9.
When is the programme active?
The programme started in April 2007 with funding for 5 years.
Brief summary of the programme fieldwork/data
Programme fieldwork and data collection are to be achieved through:
- physical, biological and chemical parameters sampling throughout the North and South Atlantic during collaborative research cruises aboard NERC's research vessels RRS Discovery, RRS James Cook and RRS James Clark Ross;
- the Continuous Plankton Recorder being deployed by SAHFOS in the North Atlantic and North Pacific on 'ships of opportunity';
- physical parameters measured and relayed in near real-time by fixed moorings and ARGO floats;
- coastal and shelf sea observatory data (Liverpool Bay Coastal Observatory (LBCO) and Western Channel Observatory (WCO)) using the RV Prince Madog and RV Quest.
The data is to be fed into models for validation and future projections. Greater detail can be found in the Theme documents.
Oceans 2025 Theme 2: Marine Biogeochemical Cycles
Marine biogeochemical cycles are the key processes that control the cycling of climate-active gases within the surface ocean; the main transport mechanisms governing the supply of nutrients from deeper waters across the pycnocline; and the flux of material to deep water via the biological carbon pump. The broad aim of this Theme is to improve knowledge of major biogeochemical processes in the surface layer of the Atlantic Ocean and UK shelf seas in order to develop accurate models of these systems. This strategic research will result in predictions of how the ocean will respond to, and either ameliorate or worsen, climate change and ocean acidification.
Theme 2 comprises three Research Units and ten Work Packages. Theme 2 addresses the following pivotal biogeochemical pathways and processes:
- The oceans and shelf seas as a source and sink of climate-active gases
- The importance of the carbon and nitrogen cycles in the regulation of microbial communities and hence export and biogenic gas cycling
- The biological pump and export of carbon into the ocean's interior
- Processes that introduce nutrients into the euphotic zone
- The direct impact of a high CO2 world (acidification) on mixed-layer biogeochemical cycles and feedbacks to the atmosphere via sea/air gas fluxes and the biological pump
- The indirect impact of a high CO2 world (increased stratification and storminess) on the supply of nutrients to the surface layer of the ocean and hence on the biological carbon pump and air-sea gas fluxes
- Cellular processes that mediate calcification in coccolithophores and how these are impacted by environmental change with a focus on elevated CO2 and ocean acidification
- Inter- and intra-specific genetic diversity and inter-specific physiological plasticity in coccolithophores and the consequences of rapid environmental change
The official Oceans 2025 documentation for this Theme can be found using the following link: Oceans 2025 Theme 2
Oceans 2025 Theme 2, Work Package 2.5: Physical Processes and the Supply of Nutrients to the Euphotic Zone
The emphasis behind this Work Package is to gain a better understanding of the ocean's biological carbon pump (OBP), an important process in the global carbon cycle. Small changes in its magnitude resulting from climate change could have significant effects, both on the ocean's ability to sequester CO2 and on the natural flux of marine carbon. This work package is concerned with the effect of physical processes and circulation on nutrient supply to the euphotic zone. Many physical pathways influence nutrient supply, such as winter overturning, Ekman pumping, small-scale turbulent mixing and mesoscale ageostrophic circulations, (of which, eddy pumping is but one example). Increased stratification will change patterns of winter overturning and dampen small-scale mixing. Shifts in wind patterns will perturb Ekman pumping. Changes in gradients of ocean heating and wind-forcing will alter the distribution of potential energy released through baroclinic instability of eddies and fronts. The combined effect of change on total nutrient supply will therefore be complex. Such physically-mediated changes, coupled to changes in aeolian dust deposition, may profoundly alter upper ocean plankton communities, biogeochemical cycling and carbon export.
This Work Package will be primarily coordinated by the National Oceanography Centre, Southampton (NOC). Specific objectives are:
- To determine the relative importance of mechanisms affecting nutrient supply to the photic zone by quantifying them in the three major biomes of the North Atlantic
- To establish how representative process studies are for the basin scale and thus define operators to scale up the individual process study results
- To determine the sensitivity to future climate change of the mechanisms sustaining total nutrient supply to the photic zone over the three major biomes of the North Atlantic
Aspects of this work will link to Oceans 2025 Theme 9 and 10, and Theme 2 WP 2.6.
More detailed information on this Work Package is available from pages 13-15 of the official Oceans 2025 Theme 2 document: Oceans 2025 Theme 2
Weblink: http://www.oceans2025.org/
Oceans 2025 Theme 5: Continental Margins and the Deep Ocean
The deep ocean and the seafloor beneath it are the largest yet least known environments on our planet. They profoundly influence the way in which the Earth reacts to climate change, provide vital resources, and can cause natural catastrophes (with significant risks to the UK). A better understanding of the biodiversity and resource potential of the deep ocean, its geophysics and its complex interactions with the global carbon cycle are all urgently required.
The overall aim of Theme 5 is to deliver coordinated, multidisciplinary research on the functioning of the deep ocean from the photic zone to the sub-seabed, encompassing biology, physics, geology, chemistry and mathematical modelling. Such an integrated deep-sea programme is unique in the UK and will ensure the provision of knowledge essential for underpinning UK policy in conserving marine biodiversity, controlling the effects of global change, managing ocean resources in a sustainable manner, and mitigating the effects of geohazards.
The specific objectives of Theme 5 are:
- To understand the processes controlling the vertical flux of carbon between the base of the photic zone and the seabed and to quantify this flux.
- To quantify fluxes of carbon and fluids from the sub-seabed into the deep ocean and their contribution to global carbon budgets.
- To determine how the carbon flow interacts with deep-ocean pelagic and benthic communities in the open ocean and on the continental slope.
- To investigate how benthic ecosystems on continental margins and in the deep ocean respond to spatial and temporal variation in environmental parameters.
- To understand the causes, frequency and predictability of submarine geohazards.
- To apply scientific knowledge to the sustainable management of the ocean and its resources.
Theme 5 combines two Research Units, on Continental Margins and on the Biochemistry of the Deep Ocean. Ultimately the science of the two activities will be combined, but because the methods of study and the resources needed are largely different, the work has been planned within two groups.
In Continental Margins, the physical processes regulating the transport of sediment is investigated as well as the transport of hydrocarbons and aqueous fluids from the seafloor. The effect of both of these major processes on the landscape ecology of the continental slope will be assessed. In addition, the causes, mechanisms and frequency of submarine geohazards will be studied, particularly those that potentially could have a devastating effect on coastal communities, such as earthquake and landslide-induced tsunamis. Carbon flux from the geosphere into the ocean will be assessed. The information will be used to advise on whole ecosystem management strategies, including policy issues relating to Marine Protected Areas and international treaties on the development of open ocean resources.
In Biogeochemistry of the Deep Ocean, the flux of particles through the 'twilight zone' in order to reduce the large uncertainties in our knowledge of the magnitude of the downward flux in various biogeochemical provinces of the global ocean will be studied. The twilight zone is a large biogeochemical reactor influencing the supply of nutrients to the euphotic zone and the fate of materials consigned to the deep seafloor. Theme 5 will study how zooplankton and microbes repackage and breakdown particles, and how these processes influence carbon transfer. Direct observations and experimental approaches will provide data to drive stoichiometric models of heterotrophic OM utilisation. The impact on the deep-sea benthos of repackaged OM, and the of part of surface production that by-passes twilight zone processes, will be assessed by analysing global patterns and through ROV in situ experimentation. Proven modelling expertise in upper ocean systems will be extended to benthic ecosystems utilising the information generated by bentho-pelagic coupling observations and experimental approaches.
The official Oceans 2025 documentation for this Theme is available from the following link: Oceans 2025 Theme 5
Weblink: http://www.oceans2025.org/
Oceans 2025 Theme 5, Work Package 5.7: Twilight zone dynamics
The surface ocean has been partitioned into discrete functional provinces with particular biogeochemical characteristics. In the Atlantic between 50° N and 50° S, Longhurst (1998) identified six provinces based on physical forcing and primary production. Links between these contrasting production regimes and the underlying deep ocean have not been studied in any detail. Some conceptual approaches, e.g. the bifurcation model, show how surface water production might relate to export, but this is complicated by evidence for strong decoupling between the magnitude of production and particulate export.
Physical dynamics of twilight zone (TZ). We will combine the latest technology and observational techniques to tackle the physically driven pathways to, from and through the deep ocean. On transects, we will test the hypotheses that the TZ is dominated by 3D eddy transports stirring the TZ and exchanging water across the permanent thermocline, while below there is a more quiescent weakly stratified environment dominated by slow mode barotropic flows, interrupted by topographic features over which increased velocity shear leads to enhanced diffusive mixing.
Particle flux through the twilight zone. Our understanding of deep ocean biogeochemistry, community structure and function can be improved by reducing uncertainties in the magnitude of downward flux, and how this changes with depth, region and time. In addition to carbon, this improved understanding must include all limiting elements and the wide variety of complex organic molecules that support life in the deep ocean. Large uncertainties in published data make such quantification a major challenge.
Twilight zone biogeochemistry. For comparison with the microbial community, we will address the role of zooplankton in the TZ by measuring biomass and size spectra using a video plankton camera system and laser optical plankton counter, verified with physical samples from closing nets. Community energy demand will be estimated from the size spectra and allometric relationships to quantify the role of zooplankton in TZ C flux.
Modelling the twilight zone system. For the TZ zone, our modelling approach will focus on particles and their utilisation by zooplankton and bacteria, and on comparing model output with data. Particulate OM will be divided into size classes corresponding to the size spectra of sinking particles, which has consequences for their depth penetration into the ocean. Production and consumption of dissolved OM will also be represented. Both C and N will be included as model currencies, using appropriate stoichiometric models of heterotrophic OM utilisation. Ecosystem models will be tested and analysed in 1D using ecosystem testbeds (Theme 9). The most appropriate will then be used in 3D using the Harvard Ocean Prediction System model, focussed on the fine-scale survey work proposed around the PAP site. Pelagic biology, which provides the export flux, will be developed in this model as part of Theme 2 then extended to the TZ to determine the relationship between TZ processes and variability in the euphotic zone. Climate sensitivity (wind forcing, heating) tests will also be undertaken to examine their impact on export.
More detailed information on this WP is available on page 14-16 of the official Oceans 2025 Theme 5 document: Oceans 2025 Theme 5
Weblink: http://www.oceans2025.org/
References:
Longhurst, A.R. (1998) Ecological Geography of the Sea, Academic Press, 398pp
Data Activity or Cruise Information
Cruise
| Cruise Name | D321 (D321A) |
| Departure Date | 2007-07-24 |
| Arrival Date | 2007-08-23 |
| Principal Scientist(s) | John T Allen (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 |
