Metadata Report for BODC Series Reference Number 1172710

• 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

Public domain data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

Sea-Bird 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 CTD Screening

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 infeasible values
• Inconsistencies between related information. For example:
  • Deepest CTD data cycle is significantly greater than the depth of the sea floor.
  • Times of the cruise and the start/end of the data series.
  • Length of the record, number of data cycles, cycle interval, clock error and the period over which data were collected.
  • Parameters stated as measured and the parameters actually present in the data series.
• Originator's comments on instrument/sampling device performance and data quality.

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

Data cycles are inspected using depth series plots of all parameters. These presentations undergo screening to detect infeasible values within the data cycles themselves and inconsistencies when comparing 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 following types of irregularity, each relying on visual detection in the time series plot, are amongst those that may be flagged as suspect:

• Spurious data at the start or end of the record where the instrument was recording in air
• Obvious spikes occurring in the data due electrical problems
• Constant, or near-constant, data channels

If a large percentage of the data is affected by irregularities, deemed abnormal, then instead of flagging the individual suspect values, a caution may be documented.

The following types of inconsistency are detected automatically by software:

• Data points with values outside the expected range for the parameter, as defined by the BODC parameter usage vocabulary.

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

• Maximum and minimum values of parameters (spikes excluded).
• Anomalous readings due to the CTD package being bounced through temperature and/or salinity gradients.

This 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's making are not introduced.

Instrument description document for D318 CTD

CTD unit and auxiliary sensors

The CTD unit comprised a Sea-Bird Electronics (SBE) 9plus underwater unit, an SBE 11plus deck unit and an SBE 32 carousel 24 - position system; all of which were mounted on a National Marine Facilities (NMF) 24 way stainless steel frame. 10L Niskin bottles were attached to 12 of the carousel's 24 available rosette positions. These were attached in alternate positions on the rosette, with only the odd rosette positions being used. One SBE Digiquartz pressure sensor, two SBE 3P temperature sensors and two SBE 4C conductivity sensors were attached to the CTD. Three of the auxiliary voltage channels were used. Attached to these channels were an SBE 43 dissolved oxygen sensor, a Benthos Sonar Altimeter and a Chelsea Alphatracka MKII. Also attached to the SBE 9plus was an NMF 10 kHz pinger, which was used as a backup to the Benthos PSA and as a double-check on the proximity of the CTD to the seabed. The pressure sensor was located 34 cm below the bottom of the Niskin bottles, and 124 cm below the top of the Niskin bottles.

In addition to the sensors mentioned above, three stand-alone instruments were attached to the CTD. For both legs of the cruise an RDI Workhorse 300 kHz Lowered ADCP (downwards looking master) and an RDI Broadband 150 kHz Lowered ADCP (downwards looking slave) were attached to the main CTD unit. A Valeport MIDAS SVP 6000DB Sound Velocity Probe was also attached for the first leg (D318a), however this was removed for D318b. These instruments recorded their data internally, thus their data are not available in the CTD data files and their specifications have not been included in the table below.

Originator's processing document for D318 CTD data

Sampling strategy

A total of eight CTD casts were performed during the RSS Discovery cruise D318 which took place in the Gulf of Cadiz (for more information see the D318 cruise report). The cruise was split into two legs; D318a which took place from 17 April 2007 to 23 April 2007 and D318b which was conducted between 27 April 2007 and 14 May 2007. Five CTD casts were performed on the D318a leg, with the remaining three being performed on the D318b leg. The casts conducted during D318a number from cast 001-004a. Cast 004a was a performed as a repeat of cast 004, which was aborted so that the research crew could attempt to solve a spiking issue, which had been affecting the primary temperature sensor since cast002. This attempt was unsuccessful, however between D318a and D318b the cable connecting the temperature sensor was replaced, which fixed the problem for the casts performed during D318b (casts 005-007).

The casts undertaken during D318a were performed in conjunction with the deployment of moorings at sites located on the edge of the continental shelf. For the second leg the RSS Discovery was joined by the RV Poseidon. Casts 005-007 were performed in deeper water, as repeats of casts undertaken by the RV Poseidon, whose CTD cable was limited to depths of 2,000 m. During most casts the CTD profiles stretched from the surface to approximately five metres from the bottom. This was changed to 25 m above the seabed in cast 004a, due to the excessive CTD wire angles observed. There was no requirement for the science party to work so close to the bottom during cast 007, so the downcast was halted approximately 100 m from the sea bed. A total of 42 water bottle samples were taken during the cruise for the calibration of salinity samples. Samples were taken on all casts apart from the aborted cast 004.

Data Processing

The initial post cruise processing was carried out by National Marine Facilities (NMF) using the SeaBird Electronics SeaSoft data processing software (version 5.35). The raw (.dat) files were converted from binary to engineering units and ASCII (.cnv) files using the DATCNV program. SeaBird rosette data files (.ros), which contain five second scan ranges centered on the bottle firing times, were also generated during this process. ALIGNCTD was run to advance the oxygen four seconds, compensating for a time lag in the dissolved oxygen sensor. CELLTM was run using alpha = 0.03 and 1/beta = 7, to correct for conductivity errors induced by the transfer of heat from the conductivity cell to the seawater.

Five second bottle summaries comprising the data recorded during each bottle firing were produced by running BOTTLESUM. The DERIVE program was used to calculate salinity, sigma-theta, potential temperature, oxygen saturation and Chen-Millero sound velocities. Finally ASCIIOUT was run to export the data in 24 Hz ASCII format and SEAPLOT was used on the derived files to generate graphs (.wmf) of secondary temperature, salinity, density and sound velocity on the same 0-4000 metre scale.

Once the initial processing had been completed, further processing was carried out at the Proudman Oceanographic Laboratory (POL) by the data originator. All the channels were dropped apart from Julian day, pressure, depth, temperature and salinity. These were the only channels present in the final version of the dataset provided to BODC. Secondary temperature and salinity were provided instead of data from the primary sensors, due to the spiking in primary temperature which was observed during casts 002-004a. Previous attempts by NMF to solve this problem using WILDEDIT had proved unsuccessful. Finally, the upcast and surface soak were removed, and the data were processed into one metre depth bins, by the data originator.

Field Calibrations

Salinity

42 salinity samples were collected for the salinity calibrations. Six samples were collected from six depths during each CTD cast, except the aborted cast 004 which collected no salinity samples. The bottle samples were analysed using a Guildline Autosal 8400B salinometer (s/n 60839). The salinometer was operated in the constant temperature (CT) lab with a bath temperature of 24 °C. The ambient room temperature of the CT lab was 22-22.5°C. The temperature stability in the CT lab was very good and yielded trouble free salinometry. The CTD samples were taken and run using a Softsal PC by NMF. All samples were processed according to World Ocean Circulation Experiment (WOCE) standards and protocols. The calibration equation used for secondary salinity has been provided below.

Autosal salinity = (0.997908 x CTD secondary salinity) + 0.075656

R² = 0.999982

Pressure

While the CTD was sat on deck, the average reading from the pressure sensor was 1.2 dbar. Therefore, the pressure channel has had a 1.2 dbar offset applied to it by the data originator. Depth readings from the CTD also take this offset into account.

Processing of D318 CTD data by BODC

BODC received eight ASCII format CTD series, which were the seven completed casts plus the aborted cast 004. Only the downcast was provided and the Originator had binned the data at one metre intervals. In addition to these files, BODC have also received the post-cruise backup of these data from National Marine Facilities (NMF), which consisted of raw and processed versions of the data as well as some supplementary information. These data have not been processed by BODC but are available on request. Following standard BODC procedure, the binned data files were processed and reformatted to BODC internal format. The aborted cast was also transferred because communications with the Originator and inspection of the data revealed that the series contained usable data. The table below shows how the variables within the processed data files were mapped to 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, missing data by both setting the data to an appropriate value and setting the quality control flag.

References

Fofonoff, NP and Millard, RC. 1983. Algorithms for computations of fundamental properties of seawater. UNESCO Technical Papers in Marine Science, 44, p.53.

Project Information

Oceans 2025 Theme 3, Work Package 3.1: Global Impacts of Shelf Seas

At the margins of the shelf seas, steep shelf-slope bathymetry has impacts on ocean circulation and the transmission of signals around the ocean basins (Hughes and Meredith, 2006), while dense water formation and cascades at the shelf edge are thought to be important for water mass formation (Ivanov et al., 2004) and for the off-shelf transport of organic and inorganic carbon (e.g. Wollast and Chou, 2001).

In this Work Package, the Proudman Oceanographic Laboratory (POL) aim to quantify the water fluxes between the shelf and open ocean globally, including the development of methods to incorporate shelf effects into global models. Greater understanding of the whole carbon cycle will benefit from combining this work on down-slope fluxes of water (and its constituent dissolved carbon) with work in Oceans 2025 Theme 5 (down-slope transports of sediments and particulate carbon).

The specific objectives are:

• Quantify and predict dense-water formation, cascading, slope mixing, their effects in the ocean
• Determine constraints that the ocean margin imposes on adjacent ocean circulation and fields
• Quantify and predict shelf seas' contribution to global biogeochemical budgets:
  • Ocean-margin fluxes and budgets of P, N, C, production and CO2
  • The shelf-ocean carbon "pump" (Yool and Fasham, 2001) and its dependence on context
  • The shelf seas' role in large-scale transport, especially of freshwater and pollutants

More detailed information on this Work Package is available at pages 5 - 27 of the official Oceans 2025 Theme 3 document: Oceans 2025 Theme 3

Weblink: http://www.oceans2025.org/

Some data used in Work Package 3.1 were collected to complement work carried out on the European Union's Geophysical Oceanography (GO) project. For these data, linkage to the GO project documentation is provided

References:

Hughes CW. and Meredith MP., 2006. Coherent sea level fluctuations along the global continental slope. Phil Trans Roy Soc A, 364, 885-901.

Ivanov VV., Shapiro GI., Huthnance JM., Aleynik DL. and Golovin PN., 2004. Cascades of dense water around the world ocean. Progr in Oceanogr, 60(1), 47-98.

Wollast R. and Chou L., 2001. Ocean margin exchange in the northern Gulf of Biscay: OMEX I. An introduction. Deep Sea Res II 48, 2971-2978.

Yool A. and Fasham MJR., 2001. An examination of the 'continental shelf pump' in an open ocean general circulation model. Global Biogeochem Cycles, 15, 831-844.

Oceans 2025 Theme 3: Shelf and Coastal Processes

Over the next 20 years, UK local marine environments are predicted to experience ever-increasing rates of change - including increased temperature and seawater acidity, changing freshwater run-off, changes in sea level, and a likely increase in flooding events - causing great concern for those charged with their management and protection. The future quality, health and sustainability of UK marine waters require improved appreciation of the complex interactions that occur not only within the coastal and shelf environment, but also between the environment and human actions. This knowledge must primarily be provided by whole-system operational numerical models, able to provide reliable predictions of short and long-term system responses to change.

However, such tools are only viable if scientists understand the underlying processes they are attempting to model and can interpret the resulting data. Many fundamental processes in shelf edge, shelf, coastal and estuarine systems, particularly across key interfaces in the environment, are not fully understood.

Theme 3 addresses the following broad questions:

• How do biological, physical and chemical processes interact within shelf, coastal and estuarine systems, particularly at key environmental interfaces (e.g. coastline, sediment-water interface, thermocline, fronts and the shelf edge)?
• What are the consequences of these interactions on the functioning of the whole coastal system, including its sensitivity and/or resilience to change?
• Ultimately, what changes should be expected to be seen in the UK coastal environment over the next 50 years and beyond and how might these changes be transmitted into the open ocean?

Within Oceans 2025, Theme 3 will develop the necessary understanding of interacting processes to enable the consequences of environmental and anthropogenic change on UK shelf seas, coasts and estuaries to be predicted. Theme 3 will also provide knowledge that can improve the forecasting capability of models being used for the operational management of human activities in the coastal marine environment. Theme 3 is therefore directly relevant to all three of NERC's current strategic priorities; Earth's Life-Support Systems, Climate Change, and Sustainable Economies

The official Oceans 2025 documentation for this Theme is available from the following link: Oceans 2025 Theme 3

Weblink: http://www.oceans2025.org/

Geophysical Oceanography

This project was funded by the European Union (EU) as part of Framework 6 - New and Emerging Science and Technologies (NEST) programme. The project ran from 01 February 2006 to 30 September 2009. There were eight scientific institutions involved in the project:

• University of Durham
• Proudman Oceanographic Laboratory (POL)
• Helmholtz Centre for Ocean Research Kiel (IFM-GEOMAR)
• French Research Institute for Exploitation of the Sea (IFREMER)
• Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA)
• The Spanish National Research Council (CSIC)
• University of Western Brittany
• University of Lisbon

Research aims

The primary aims of Geophysical Oceanography (GO) project were to provide a calibration between seismic images of water structure and conventional oceanographic measurements, in addition to testing various seismic acquisition systems and novel geometries for seismic imaging of water structure. In particular, this project examined internal waves and their interaction with the continental slope, while using extensive marine geophysical knowledge acquired over the past 4 decades to evaluate longer term changes in the ocean structure.

Fieldwork

Research for GO was conducted during RSS Discovery cruise D318, which was split into two legs, D318a and D318b. The research was conducted between 17 April 2007 and 14 May 2007 in the Gulf of Cadiz. For leg D318b, RSS Discovery was joined by RV Poseidon cruise PO350 (funded under a separate grant from the German research council with project partners IFM-GEOMAR). Some of the fieldwork provided data for Natural Environment Research Council (NERC) Oceans 2025 Theme 3 Work Package 3.1 as well as for GO. These data have been tagged accordingly below.

GO fieldwork objectives

The primary objectives of the GO project were:

• To evaluate and improve new research methods in the developing field of seismic oceanography by exploiting the opportunity of two-ship operations between RSS Discovery and RV Poseidon
• To study the internal wave field and mixing processes in the Gulf of Cadiz and demonstrate quantitative links between seismic and oceanographic measurements.

The main objectives of cruise D318 were:

• To collect a co-located and co-incident seismic reflection and physical oceanography calibration dataset including:
• Seabed measurements of both oceanographic and seismic data
• Conventional CTD casts
• Seismic multichannel reflection data
• Underway oceanographic data measurements

The main objective of cruise PO350 was:

• To obtain accurate hydrographic and ocean current data to combine with seismic measurements collected by the RSS Discovery

D318 measurements

• CTD casts
• Moorings
• STABLE (Sediment Transport And Boundary Layer Equipment)
• One 75 KHz ADCP
• Two 150 KHz ADCP
• One 600 KHz ADCP
• Three lines of Vemco miniloggers
• XBT casts (NERC Oceans 2025 data)
• XCTD casts (NERC Oceans 2025 data)
• High resolution seismic data acquisition devices
• SEDERA Generator Injector (GI) airgun
• 600 m SERCEL streamer
• Low resolution seismic data acquisition devices
• Bolt 1500LL Airgun
• 2400 m SERCEL streamer

PO350 measurements

• CTD casts
• Lowered ADCP casts - LADCP was attached to the CTD rosette
• One 300kHz LADCP
• One 1200kHz LADCP
• Vessel-Mounted ADCP measurements
• XBT casts
• Deployment and recovery of several Ocean Bottom Hydrophones (OBH) - used to record the seismic signals from RSS Discovery
• Vertical seismic profiler (VSP) casts
• Two autonomous gilders

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

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:

SeaDataNet Quality Control Flags

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