Metadata Report for BODC Series Reference Number 1207730

• 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

RD Instruments- Ocean Surveyor 75kHz Vessel mounted ADCP.

¹ Ranges at 1 to 5 knots ship speed are typical and vary with situation.
² Single-ping standard deviation.
³ User's choice of depth cell size is not limited to the typical values specified.

Profile Parameters

• Velocity long-term accuracy (typical): ±1.0%, ±0.5cm/s
• Velocity range: -5 to 9m/s
• # of depth cells: 1 - 128
• Max ping rate: 0.7

Bottom Track

Maximum altitude (precision <2cm/s): 950m

Echo Intensity Profile

Dynamic range: 80dB
Precision: ±1.5dB

Transducer and Hardware

Beam angle: 30°
Configuration: 4-beam phased array
Communications: RS-232 or RS-422 hex-ASCII or binary output at 1200 - 115,200 baud
Output power: 1000W

Standard Sensors

Temperature (mounted on transducer)

• Range: -5° to 45°C
• Precision: ±0.1°C
• Resolution: 0.03°

Environmental

Operating temperature: -5° to 40°C (-5° to 45°C)*
Storage temperature: -30° to 50°C (-30° to 60°C)*

*later instruments have greater range.

Web Page

Further details can be found on the manufacturer's website or in the specification sheet

D351 Vessel Mounted ADCP Data Document

The following contains extracts from the D351 cruise report.

Originator's Protocol for Data Acquisition and Analysis

The RRS Discovery D351 funded by NERC was part of the Oceans 2025 programme. The programme ran for five years with the aim of improving our understanding of how our seas behave and how they are changing, and what that might mean not just for our oceans, but for society.

D351 departed on 11 May 2010 from the port of Reykjavík, Iceland and returned on the 28 May 2010 to the port of Govan, United Kingdom.

Sample collection

The RRS Discovery D351 was equipped with two hull mounted Ocean Surveyor broadband ADCPs. An RDI broadband 150 kHz ADCP is mounted in the hull 1.75 m to port of the keel, 33 m aft of the bow at the waterline, at an approximate depth of 5.3 m. A 75 kHz ADCP is also mounted in the hull, in a second well 4.15 m forward and 2.5 m to starboard of the 150 kHz well.

The RDI Ocean Surveyor 150 kHz Phased Array VMADCP was configured to sample over 120 second intervals with 96 bins of 4 m depth and a blank beyond transmit of distance of 4 m. The instrument is a broad-band phased array ADCP with 153.6 kHz frequency and a 30° beam angle.

The RDI Ocean Surveyor 75 kHz Phased Array VMADCP was configured to sample over 120 second intervals with 100 bins of 8 m depth and a blank beyond transmit of distance of 8 m. The instrument is a broad-band phased array ADCP with 76.8 kHz frequency and a 30° beam angle.

Data Processing Navigation

The ship's primary position instrument was the GPS Trimble 4000 system. The GPS 4000 system has sufficient precision to enable the calculation of ship's velocities to better than 1 cms^-1, and therefore below the instrumental limits (~ 1 cms^{- 1}) of the RDI ADCP systems.

Navigation and gyro data were transferred daily from the RVS format file streams to pstar navigation files.

• navexec0: transferred data from the RVS bestnav file to PSTAR, calculated the ships velocity, appended onto the absolute (master) navigation file and calculated the distance run from the start of the master file.

• gyroexec0: transferred data from the RVS gyronmea file to PSTAR, a nominal edit was made for directions between 0-360° before the file was appended to the master file.

• gps4exec0: transferred data from the RVS gps_4000 file to PSTAR, edited out pdop (position dilution of precision) greater than 7 and appended the new 24 hour file to a master file. The master file was averaged to create an additional 30 second file and distance run was calculated.

Data Processing VMADCP

Data were processed using the following scripts:

• s75exec0 and s150exec0: data read into Pstar format from the raw RDI binary format file; Water track velocities written into 'sur' files (75 kHz) or 'adp' files (150 kHz) and bottom track into 'sbt' files whilst in bottom track mode. Velocities scaled to cm/s and amplitudes by 0.45 into db. Time variable corrected to GPS time by combining the PC clock time and the PC-GPS. Bin depths adjusted to correct depths.

• s75exec1 and s150exec1: data edited according to status flags (velocity data replaced with absent data if variable '2+bmbad' was greater than 25%). Time of ensemble moved to the end of ensemble period.

• s75exec2 and s150exec2: merged data with Ashtech-a ghdg. ADCP velocities converted to speed and direction allowing heading correction to be applied. ADCP velocities returned to east and north components.

• s75exec3 and s150exec3: applied misalignment angle ø and scaling factor A.

• s75exec4 and s150exec4: merged ADCP data with the bestnav data. Ship's velocity calculated from spot positions and applied to ADCP velocity producing absolute velocity of the water. Time base of ADCP profiles shifted to the centre of the 2 minute ensemble by subtracting 60 seconds.

Calibration

Calibration was achieved by using bottom tracking data made available after departure from Reykjavík across the Icelandic continental shelf. Using long, straight and steady speed sections of standard 2 minute ensemble profiles over reasonably constant depths the following calibrations for misalignment angle, ø, and necessary amplification (tilt), A, were derived:

References

Read, J. F. (2010). 'The Extended Ellett Line 2010'. Cruise Report No. 50National Oceanography Centre, Southampton.

Processing by BODC of RRS Discovery Vessel Mounted ADCP data

The data arrived at BODC in daily PStar files representing the data collected from the vessel mounted ADCP during cruise D351. The data were reformatted to BODC's internal NetCDF format. The following table shows the mapping of variables within the PStar file 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.

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 10

Oceans 2025 is a strategic marine science programme, bringing marine researchers together to increase people's knowledge of the marine environment so that they are better able to protect it for future generations.

Theme 10: Integration of Sustained Observations in the Marine Environment spans all marine domains from the sea-shore to the global ocean, providing data and knowledge on a wide range of ecosystem properties and processes (from ocean circulation to biodiversity) that are critical to understanding Earth system behaviour and identifying change. They have been developed not merely to provide long-term data sets, but to capture extreme or episodic events, and play a key role in the initialisation and validation of models. Many of these SOs will be integrated into the newly developing UK Marine Monitoring Strategy - evolving from the Defra reports Safeguarding our Seas (2002) and Charting Progress (2005), thus contributing to the underpinning knowledge for national marine stewardship. They will also contribute to the UK GOOS Strategic Plan (IACMST, 2006) and the Global Marine Assessment.

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

Oceans 2025 Theme 10, Sustained Observation Activity 4: The Extended Ellett Line

The Ellett Line (begun in 1975 and since 1996 the Extended Ellett Line from Scotland to Iceland) crosses important north Atlantic Meridional Overturning Circulation (MOC) components and thus provides an additional contribution to understanding the north Atlantic response to climate change. Sustained Observation Activity (SO) 4 will repeat this section annually collecting a wide variety of physical and biogeochemical measurements, and will, to enhance the time variable component, make use of Argo floats and gliders. SO 4 will be implemented by physical, biological and chemical scientists at the National Oceanography Centre, Southampton (NOCS) and the Scottish Association for Marine Science (SAMS).

SO 4 formally contributes to the Department for Environment, Food and Rural Affairs (DEFRA)-funded Marine Environmental Change Network (MECN). Established in 2002 to coordinate and promote the collection and utilisation of marine time-series and long-term data sets, the goal of the network is to use long-term marine environmental data from around the British Isles and Ireland to separate natural fluctuations from global, regional and local anthropogenic impacts.

The specific deliverables for SO 4 are:

• A time series of the evolution of the hydrography of the northeast Atlantic, together with a more formal understanding of the causes of any changes observed
• An archived data set available to the international community via the British Oceanographic Data Centre (BODC)
• A platform for further scientific research

More detailed information on this Work Package is available at pages 15 - 16 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10

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

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: