Metadata Report for BODC Series Reference Number 2079754

• 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

Kongsberg Simrad EA500 bathymetric echosounder

The EA500 is a bathymetric echosounder that can be used in water as deep as 10,000 m. It features triple frequency operation with a separate digitiser for each channel and high transmitted power with an instantaneous dynamic range of 160 dB. The instrument can operate with several pulses in the water simultaneously and has bottom tracking capabilities. A wide range of transducers (single beam, split beam or side-looking) is available and the ping rate is adjustable up to 10 pings per second. The split beam operation measures the athwartships inclination angle of the seabed.

This instrument was introduced in June 1989 and and replaced by the EA 600 in 2000.

Specifications

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

Ashtech G12 Global Positioning System Receiver

The Ashtech G12 Global Positioning System (GPS) uses all-in-view tracking and 12 channels to provide real time three-dimensional positional measurements. It is Differential GPS (DGPS) ready, offering an accuracy of better than 40 cm, position latency better than 50 ms, and exact position latency to millisecond accuracy.

Specifications

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

Ashtech Global Positioning System receivers (ADU series)

The ADU series of Global Positioning System (GPS) receivers are designed to give real-time three-dimensional position and attitude measurements. Attitude determination is based on differential carrier phase measurements between four antennas connected to a receiver, providing heading, pitch and roll, along with three-dimensional position and velocity.

The ADU2 model receives information from 48 channels, while the upgraded model (ADU5) uses 56 channels. The ADU5 also features a unique Kalman filter with user selectable dynamic modes to match operating conditions. It also incorporates signals from Satellite Based Augmentation Systems (SBAS) and features an embedded 2-channel 300 kHz beacon receiver for easy differential GPS (DGPS) operations.

Specifications

Further details can be found in the manufacturer's specification sheets for the ADU2 andADU5.

Chernikeeff Aquaprobe Mk5 Electromagnetic Speed Log

The Aquaprobe Mk5 EM Speed Log operates on the principle that a conductor (such as water) passing through an electromagnetic field will create a voltage whose magnitude increases as the speed of the conductor increases. The EM log includes one or two hull-mounted transducers, which generate an electromagnetic field and measure the voltage created by the flow of water through that field, thereby deducing the speed of the vessel through the water.

The EM log has the options of single or twin transducers, single or dual axis speed measurements and gate-valved (retractable) hull fitting or fixed transducers. The microprocessor calibration control ensures a high accuracy through the entire speed range.

Specifications

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

D346 Underway Navigation Instrumentation

The following scientific navigational and bathymetric systems were fitted.

The RRS Discovery has a variety of GPS receivers: the Trimble 4000, which is a differential GPS; the Ashtech ADU2; and the Ashtech G12 - integrated into the Fugro SeaSTAR 9200-G2 navigation system. The ship also uses a gyrocompass and Chernikeeff Electromagnetic (EM) log to measure ship heading and speed.

Fugro SeaSTAR 9200-G2 Receiver

The SeaSTAR 9200-G2 is a dual frequency (L1/L2) receiver that incorporates global positioning system (GPS) and global navigation satellite system (GLONASS) reception capability while tracking the Fugro L-Band satellite broadcast of Differential Global Satellite Navigation System (DGSNS) corrections. These corrections can also be received via internet, as a backup.

The SeaSTAR 9200-G2 can be used in conjunction with other services as HP (GPS network solution), XP (GPS or orbit and clock solution) and G2 (Composite GPS/GLONASS orbit and clock solution). These are also dual frequency carrier phase solutions, which allows for a decimeter level accuracy.

The 72 channels received by the SeaSTAR include GPS- L1 C/A code and L1/L2/L2C full cycle carrier, GLONASS- L1/L2 full cycle carrier, Satellite Based Augmentation System (SBAS) and the Fugro L-Band service.

Specifications

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

Trimble 4000DS Global Positioning System receiver

The Trimble 4000DS Differential Surveyor is similar to the 4000RS (a Maxwell-based receiver that is oriented toward precision positioning applications. It is intended for use as a DGPS base station, generating RTCM-104 corrections). The 4000Ds can apply RTCM-104 corrections to the satellite data it receives in order to generate accurate position fixes in real time.

RAPID Cruise D346 Underway Navigation, Meteorology and Sea Surface Hydrography Series

Cruise details

Cruise D346 occupied a hydrographic section at a nominal latitude of 24.5°N in the Atlantic Ocean during January - February 2010 on RRS Discovery. The primary objective of this cruise was to measure ocean physical, chemical and biological parameters in order to establish regional budgets of heat, freshwater and carbon, and to infer decadal variability.

Content of data series

Instrumentation

Sea surface hydrography (HIUWAY)

The instruments used to collect this data set are presented in the table below:

Near surface temperature was measured with a SBE 38 probe located in the forward hold on the starboard side, measuring the temperature of water 6-7 metres below the surface. The seawater intake projects about 0.5 metres below the hull.

A SBE45 MicroTSG is fitted in the wet lab and the non-toxic supply runs from this intake. Samples were taken every four hours from the non-toxic supply on the upstream side of the SBE 45 in order to calibrate the conductivity data.

Meteorology (HIMET)

The instruments used to collect this data set are presented in the table below:

All instruments are located on the foremast in order to obtain the best exposure.

Navigation and bathymetry (HIPLAT)

The RRS Discovery has three GPS receivers: the Trimble 4000, which is a differential GPS; the Ashtech and the GPS G12. The ship also uses a gyrocompass and Chernikeeff Electromagnetic (EM) log to measure speed and heading.

Bathymetric depth data were obtained using a Simrad EA500 hydrographic echosounder and a Precision Echosounding transducer (PES) mounted in a 'Fish'.

Data processing procedures

Sea surface hydrography (HPUWAY)

Originator's processing

Data were taken from the ship's TECHSAS streams and formatted into MSTAR netCDF format. All times were defined as seconds from 00:00:00 01/01/2010.

The hydrography measurements were performed by a number of instruments in the ship's flow through system and a temperature sensor (SBE38) located near the flow through intake. A SBE45 MicroTSG was used in the wet lab, measuring the temperature and conductivity of the water pumped up through the ship's flow through system.

Salinity data were calibrated by calibrating the conductivity channel and then deriving salinity. Discrete bottle conductivities were compared with the TSG conductivities.

BODC processing

All 1 second sea surface hydrographic data were transferred from an MSTAR format into a BODC internal format (a netCDF subset) to allow use of the in-house visualisation tool (EDSERPLO). All hydrography parameters were matched against BODC codes as presented in the table above. Reformatting and data calibration was carried out, and is discussed below. Each data channel was visually inspected and any spikes or periods of dubious data flagged as suspect with an 'M'. The capabilities of the screening software allows comparative screening checks between channels.

All parameters were screened in EDSERPLO and suspect data were flagged.

• Temperature

  The hull temperature data were calibrated at BODC using CTD temperature data. The offset (CTD temperature - Underway temperature) was examined to see if it varied with time or temperature. Outliers, with high standard deviations, were identified and discarded. A significant correlation was found to exist between the offset and CTD temperature or time. Therefore the data correction is in the form of a regression equation (n = 129, standard deviation = 0.01361 with a P value of 0.000):

  Regression equation:

  Offset = -0.0805 + 0.00338 * CTD temperature

  Therefore:

  Calibrated underway temperature = (1.003391 * underway temperature) - 0.0807730

  with an R² value of 0.0%

• Salinity

  Salinity data were calibrated at BODC using 193 discrete TSG samples collected during the cruise. The offset (discrete TSG samples - underway salinity) was examined to determine if it varied with salinity or time. Outliers with high standard deviations were identified and removed. A significant correlation and trend existed between the offset and discrete TSG samples (n = 182, standard deviation = 0.004995, with a P value of 0.001) and so a regression equation was applied to calibrate this data:

  Regression equation:

  offset = 0.140 - 0.00381 * TSG discrete bottle samples

  Therefore

  Calibrated underway salinity = (0.996204 * underway salinity) + 0.139556

  with an R² value of 0.0%

• Beam attenuation

  Raw transmissometer data were converted to beam attenuation using the formulae:

  c=-1/0.25 x ln(tr)

  where

  Tr=(Vsig-0.060)/(4.731-0.060)

• Fluorescence

  Fluorescence data were converted from raw voltages using the formulae:

  CHL (µg/l) = 12.4 x (Output - 0.055)

  No other processing methods were carried out by BODC.

Meteorology (HPMET)

Originator's processing

Meteorological data were taken from the ship's TECHSAS streams and formatted into MSTAR netCDF format. All times were defined as seconds from 00:00:00 01/01/2010.

Wind data were collected using a Gill Windsonic anemometer which was located on the ship's foremast. This instrument measured apparent wind speed and direction during the cruise.

Speed made good and course made good are calculated and, along with corrected heading and distance run, merged onto the same time stamps as the wind data from the anemometer. Wind speed and direction were corrected on board by the Originator to remove the effects of ship movement.

Port and starboard PAR and TIR sensors on the foremast and air pressure from the barometer in the main lab were logged to a separate TECHSAS file. These were then reformatted into MSTAR netCDF. Manufacturer's calibrations were applied to convert the data into physical units.

Humidity and air temperature were recorded using a Vaisala HMP45A probe located on the starboard side of the foremast. All data were logged using the TECHSAS system.

BODC processing

All 1 second meteorological data were transferred from an MSTAR format a into BODC internal format (a netCDF subset) to allow use of the in-house visualisation tool (EDSERPLO). Reformatting and data calibration was carried out, and is discussed below. Each data channel was visually inspected and any spikes or periods of dubious data flagged as suspect. The capabilities of the screening software allows comparative screening checks between channels.

All parameters were screened in EDSERPLO and suspect data were flagged.

Records from the port and starboard PAR and solar radiation channels were each merged into a single channel by taking the maximum of the port or starboard sensor value at every cycle to minimise shading effects.

Navigation and bathymetry (HPPLAT)

Originator's processing

Bathymetry data were taken from the ship's TECHSAS streams and formatted into MSTAR netCDF format. All times were defined as seconds from 00:00:00 01/01/2010. Depths from the echosounder were visualised and bad data replaced with NaNs. A Carter correction was then applied.

All navigational data were downloaded from the TECHSAS system. Data from the Ashtech GPS was used to correct the heading given by the gyro compass. The differences were calculated and then cleaned to produce a correction. This was then applied to the heading from the gyro compass.

BODC processing

All 1 second navigational data were transferred from an MSTAR format into a BODC internal format (a netCDF subset) to allow use of the in-house visualisation tool (EDSERPLO). Reformatting and data calibration was carried out, and is discussed below. Each data channel was visually inspected and any spikes or periods of dubious data flagged as suspect. The capabilities of the screening software allows comparative screening checks between channels.

All parameters were screened in EDSERPLO and suspect data were flagged.

Navigation was checked for gaps and improbable ship speeds at BODC. No improbable speeds were found and so no interpolation was required.

Distance run was recalculated using the clean latitude and longitude at BODC.

References

King, B.A., McCarthy, G., Hamersley, D.R.C. (ed.) (2012) RRS DiscoveryCruise D346, 05 Jan - 19 Feb 2011. The 2010 transatlantic hydrography section at 24.5 ° N. Southampton, UK, National Oceanography Centre, Southampton, 177pp. (National Oceanography Centre Southampton Cruise Report, 97-120).

Data quality report

Sea surface hydrography (HQUWAY)

Transmissometer: Noise is present in the transmissometer channel, mainly occurring between 18 January 2010 00:08:00 and 27 January 2010 21:44:00. There is also some uncertainty over the units assigned to this parameter by the Originator. The Originator provided these data to BODC with a unit of millivolts, however, further investigation shows that these original data might actually have been supplied in volts. These data should therefore be used with caution at the discretion of the user.

All other channels are of good quality with erroneous points marked suspect.

Meteorology (HQMET)

Negative solar radiation and PAR irradiance that occur at night have been flagged suspect.

Navigation and bathymetry (HQPLAT)

All channels are of good quality with erroneous points marked suspect.

BODC quality control flags

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

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 1: Climate, Ocean Circulation and Sea Level

Through fieldwork, analysis and modelling, Theme 1 will provide detailed knowledge of how the Atlantic, Arctic and Southern Oceans are responding to, and driving, climate change. In combination with geodetic studies, it will also improve our ability to predict global sea level and UK land movements in the century ahead.

The official Oceans 2025 documentation for this Theme is available from the following link: Oceans 2025 Theme 1

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

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: