Metadata Report for BODC Series Reference Number 888107

• 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

Problem Reports

No Problem Report Found in the Database

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

Instrument Description

CTD Unit and Auxiliary Sensors

See the Cruise Report for more details on the sensors.

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:

Further details can be found in the manufacturer's specification sheet.

BODC Processing

The data arrived at BODC in 11 Ascii files, representing eleven of the twelve CTD casts taken during the cruise. One of the ctd files had been accidentally overwritten on board the ship thus was unavailable for archiving. These eleven files were reformatted to the internal QXF format using BODC transfer function 401. The following table shows how the variables were mapped to the appropriate BODC parameter codes.

The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag.

BODC also hold original SeaBird files of this data, which are available on request.

Originator's Data Processing

Sampling Strategy

A total of twelve CTD stations were completed during CE0716, four deep casts for both SBE Microcat calibration and acoustic release tests, three to 2500m in a triangle around the PAP site and 5 in support of near surface bottle sample measurements.

Data Processing

During the first CTD profile, a problem became apparent when unrealistic temperature and salinity values were registered, most notably in salinity. The sensor was changed and at the second attempt values were still not realistic. Subsequent investigations revealed that incorrect calibration coefficients for the temperature had been input into the CTD configuration file prior to the survey. These coefficients were corrected and the CTD performed well thereafter. The raw data were re-processed post-cruise to obtain the correct calibration data for the Microcats.

An initial view of the CTD data on-board revealed that it was clean with no obvious irregularities in any measurements.

The data were processed by Martin White, University of Ireland, Galway, using his own routines, rather than the SeaBird software. The temperature and conductivity data were run through a 121 point median filter (about 5 seconds in time) before salinity was calculated. Then the salinity was run through the same filter before density was calculated.

Then the equivalent of loop edit was run before the 1 db averages were calculated.

General Data Screening carried out by BODC

BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.

Header information is inspected for:

• Irregularities such as unfeasible values
• Inconsistencies between related information, for example:
  • Times for instrument deployment and for start/end of data series
  • Length of record and the number of data cycles/cycle interval
  • Parameters expected and the parameters actually present in the data cycles
• Originator's comments on meter/mooring performance and data quality

Documents are written by BODC highlighting irregularities which cannot be resolved.

Data cycles are inspected using time or depth series plots of all parameters. Currents are additionally inspected using vector scatter plots and time series plots of North and East velocity components. These presentations undergo intrinsic and extrinsic screening to detect infeasible values within the data cycles themselves and inconsistencies as seen when comparing characteristics of adjacent data sets displaced with respect to depth, position or time. Values suspected of being of non-oceanographic origin may be tagged with the BODC flag denoting suspect value; the data values will not be altered.

The following types of irregularity, each relying on visual detection in the plot, are amongst those which may be flagged as suspect:

• Spurious data at the start or end of the record.
• Obvious spikes occurring in periods free from meteorological disturbance.
• A sequence of constant values in consecutive data cycles.

If a large percentage of the data is affected by irregularities then a Problem Report will be written rather than flagging the individual suspect values. Problem Reports are also used to highlight irregularities seen in the graphical data presentations.

Inconsistencies between the characteristics of the data set and those of its neighbours are sought and, where necessary, documented. This covers inconsistencies such as the following:

• Maximum and minimum values of parameters (spikes excluded).
• The occurrence of meteorological events.

This intrinsic and extrinsic screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC making are not introduced.

Project Information

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

Porcupine Abyssal Plain (PAP) Observatory

Scientific Rationale

During the past decade, the intention has been to observe changes in rate and state variables within the entire water column and benthos, for a wide range of biogeochemically significant features in the centre of the Porcupine Abyssal Plain. The site appears to satisfy many of the conditions for simplicity; it lies well away from regions where physical gradients are strong and is in the middle of one of the biogeochemical provinces. The seabed is very flat over large areas (4800m depth) and there is no evidence of significant advective supply of material. Below the upper mixed layer, currents are generally northerly and of low velocity. The depth of winter mixing is large and variable (300-800m) and this facilitates research into the effects of the most important driving force on upper ocean biogeochemistry: nutrient supply. There is a substantial data base from previous programs on which to build: the PAP site is about 350Km to the northeast of the site of the JGOFS North Atlantic Bloom Experiment in 1989 (see Deep Sea Research volume 40 1-2) and the continuing work by IFM, Kiel. It was the focus of the EU BENGAL program from 1998-2001 (See Progress in Oceanography volume 50 1-4) and is at the northern boundary of the French POMME program. Ships of opportunity contribute significantly with frequent transects by the Continuous Plankton Recorder since 1949 and PCO2 transects under the EU program CAVASSOO. It was a focus of the then SOC Deacon Divison core research program BICEP which draws the link between upper ocean processes and the deep ocean benthos where there has been a major biological regime shift in the mid 1990's.

At the beginning of the project in 2002, three moorings were deployed at the PAP site with the intention of recovering and redeploying each of them annually.

The three moorings deployed comprised the following:

• A titanium frame positioned in the eutrophic zone carrying the Fluorimeter Nitrate analyser, CO2 sensor, and temperature, salinity and pressure sensor. Below this at 150m were ADCPs, measuring direction and speed of the current.
• A mooring with a surface buoy communicating in near real-time, via satellites, sending temperatures and salinities from up to 12 sensors positioned at depths of between 10m and 1000m.
• A mooring with sediment traps and current meters.

References

Billett, D.S.M., Bett B.J., Reid, W.D.K., Boorman, B. and Priede, M. Long-term change in the abyssal NE Atlantic: The 'Amperima Event' revisited. Deep Sea Research II; PAP special volume (Submitted)

Hartman. S., Larkin. K. E., Lampitt, R. S, Koeve, W., Yool, A., Körtzinger, A., Hydes, D.J. (This volume) Seasonal and inter-annual biogeochemical variations at PAP (49°N, 16.5°W) 2003-2005. Deep Sea Research II; PAP special volume (Submitted)

Gooday, A et al. Long term change in foraminiferans Deep Sea Research II, PAP special volume (Submitted)

Martin, A.P., Lucas, M.I., Painter, S.C., Pidcock, R., Prandke H., Prandke,H., Stinchcombe, M.C. (2008) The supply of nutrients due to vertical turbulent mixing: a study at the Porcupine Abyssal Plain study site (49°50'N 16°30'W) in the northeast Atlantic. Deep Sea Research II, PAP special volume (Submitted)

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 - 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.

Data Activity or Cruise Information

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Porcupine Abyssal Plain (PAP) Observatory

The Porcupine Abyssal Plain (PAP) observatory is a site at which moorings were deployed in the Northeastern Atlantic, as part of the ANIMATE (Atlantic Network of Interdisciplinary Moorings and Time-series for Europe), MERSEA (Marine Environment and Security for the European Area), EuroSITES, Oceans2025, Fix03 and CLASS projects. The PAP site is centred at latitude 49° N and longitude 16.5° W. Moorings have occupied this region since 2002 and are typically deployed for 12 months.

Please note: Near Real Time data is only stored at BODC where delayed mode data were not recovered. All near real time data can be found at the OceanSites GDA and through IFREMER.

Data summary

Status Indicators

Related Fixed Station activities are detailed in Appendix 1

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Appendix 1: Porcupine Abyssal Plain (PAP)

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.