Metadata Report for BODC Series Reference Number 1903908

• 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

Bathymetry

The single beam echo sounder readings were very noisy and the channel experienced a large drop out in signal between 07/12/2017 10:52:00 - 16/12/2017 17:13:00. The data should be used with caution.

RRS James Clark Ross cruise JR17001 Navigation quality control report

Bathymetry

The single beam bathymetry channel (MBANZZ01) and multi beam bathymetry (MBANSWCB) were compared along with the GEBCO depth channel as a reference source (MBANGB08). Both channels were noisy, however, the multi-beam bathymetry channel was a shorter time series, therefore the single beam echo sounder was the most complete channel.

Navigation channels

There is a gap of 88 minutes in the latitude and longitude channels from 12/12/2017 03:43:00 to 12/12/2017 05:10:00. There were no other sources of navigation available to use, so the gap was filled by linear interpolation. The eastward and northward velocities, and distance run channels were derived from the latitude and longitude channels. Any data derived from interpolated values, have been flagged appropraitely.

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 EA600 Single Beam Echosounder

The EA600 is a single beam echosounder with full ocean depth capability designed for bathymetric surveys. It measures water depth by monitoring the travel time of an acoustic signal that is transmitted from the ship, reflected off the seabed and received back at the ship.

The main components of the system are hull-mounted transducers linked to general purpose transceivers (GPTs). Up to four GPTs, each controlling one or more transducers, may be operated simultaneously. The GPT generates a signal, which is transmitted into the water column as an acoustic pulse by the transducer array, and the returning echo is recorded by the GPT. GPTs are in turn linked to a combined display and processor, where adjustments (such as sound-speed corrections) may be applied to the data. Available frequencies span from 12 to 710 kHz, and each GPT may operate at a separate frequency. A variety of transducers is available for water depths up to 11,000 m.

The EA600 stores all data internally but has a USB port which allows the possibility of connecting a CD-ROM/DVD drive to read and write the data. All echo data can be stored as files: bitmap, sample, depth or sidescan data.

In deeper waters, the EA600 supports a multipulse function, allowing for a higher pinger rate. While on passive mode, the pinger is normally attached to a device, with the purpose of tracking and displaying its current depth.

The EA600 replaced the EA500 in 2000.

Specifications

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

Kongsberg Seatex Seapath 320+ Precise Heading, Attitude and Positioning Sensor

The Seapath 320+ is a navigational system that combines two Global Navigation Satellite System (GNSS) receivers with a MRU 5+ inertial sensor to provide high resolution and accuracy positional data. The inertial sensor employs linear accelerometers and unique microelectromechanical systems (MEMS)-type angular rate gyros to provide 0.01 RMS pitch and roll accuracy. The GNSS receivers can use multiple satellite constellations (GPS, GLONASS and Galileo, when available), and combine data from these to improve heading and positional measurements. In case of missing data from one GNSS receiver, the other receiver provides position and velocity, and the inertial sensor provides heading from its internal rate sensors.

The main characteristics are presented below, and the specification sheet can be accessed here Kongsberg Seatex Seapath 320+ .

Specifications

RRS James Clark Ross cruise JR17001 navigation instrumentation

The following scientific navigational and bathymetric systems were fitted.

Sperry Marine MK-37 Gyrocompass

A family of instruments that contain a controlled gyroscope which seeks and aligns itself with the meridian and points to true north. They use the properties of the gyroscope in combination with the rotation of the earth and the effect of gravity. The effects of varying speed and latitude are compensated for by the use of manually operated controls. Models MOD I, MOD O, MOD D, MOD D/E are all with an analog output Step or/and Syncro. MOD VT is the latest model with NMEA Data output as well.

Further specifications for MOD VT can be found in the manufacturer's specification document.

Further information for MOD D/E can be found in the user manual.

RRS James Clark Ross Cruise JR17001 Navigation and Bathymetry Processing Procedures Document

Originator's Data Processing

The navigation and bathymetric data were measured by several different instruments and the data were logged by the NOAA SCS software on a timescale dependent on the instrument. Data were stored in comma separated ACO format. The SCS data streams (ashtech [nav/ash], ea600 [sim], anemometer [met/surfmet], oceanlogger [ocl], gyro [nav/gyros], seatex-gll [nav/seapos], em122 [em122], seatex-hdt [nav/seahead]) were processed onboard. The SCS underway data streams for navigation, meteorological parameters and thermosalinograph were read in and processed on a daily basis using Mexec v3.1. Processing included some automatic removal of out-of-range values, despiking, and averaging.

Two bathymetry streams were available via SCS: the ea600 single-beam echo sounder, and the centre beam of the em122 multibeam (swath) system. The EA600 data were frequently bad because the automatic bottom detector failed to detect the correct return. To maximise use of other acoustic instruments, the EM122 swath echosounder was turned off for much of the SR1b section (for later CTD stations, it was only turned on briefly when coming on station to get a good depth fix), and was not logged there nor in other areas where swath bathymetry had been collected previously.

Following the daily processing, bad data were selected and flagged from the EA600 and the EM122 centre beam. This flagging was interactive, based partially on comparison between the EA600 and EM122, when both were available, as well as with historic bathymetry data. The full swath data are reported but not cleaned or otherwise quality-controlled aboard the ship.

NetCDF files containing the data were generated by the originator in Mexec.

The following files were provided.

• bst: complete navigation file at half-minute intervals.
• em122: water depth from centre-beam of em122.
• ea600: ea600, corrected by Carter Area.

The table below shows the original files delivered to BODC that contained the data in the final data series, along with start and end dates and times of each file.

BODC Data Processing

The NetCDF files were provided by the originator to BODC. These files were transferred into internal BODC format using established BODC data banking procedures. The data were averaged to 60 second intervals. The originators files contained many parameters that were not transferred because they were not relevant to the final data set and several channels were derived by BODC.

The table below provides a description of the originators channels transferred, along with the BODC parameter codes, units assigned and derived variables.

Navigation channels

A check was run on the latitude and longitude channels to identify gaps in the channel. Two gaps in the navigation channels were identified at the start and end of the file and were trimmed off the data streams at the end of processing. The gaps identified are shown below.

• Gap 1 Start: 2017/11/19 00:00:00 End: 2017/11/20 23:58:59 Duration: 2880 minutes
• Gap 2 Start: 2017/12/12 03:43:00 End: 2017/12/12 05:10:00 Duration: 88 minutes
• Gap 3 Start: 2017/12/19 15:56:59 End: 2017/12/21 23:58:59 Duration: 3363 minutes

Distance Run

Distance run was derived using the seatex latitude and longitude channels using the BODC Matlab utility 'disrun'.

Ship velocities

The ship's north and east velocities were derived using the seatex latitude and longitude channels, using the BODC Matlab routine 'velcal'.

Bathymetry

Bathymetry data were screened independently as well as against GEBCO bathymetry measurements. Bathymetry data from the EA600 single-beam echo-sounder were deemed to be the longer time series. The multi-beam echo-sounder was switched on later and turned off earlier than the single-beam and so is a shorter time series of data.

Calibration

No sample calibrations were applied to these data.

Project Information

Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA)

The Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA) is a £8.4 million, five year (2016-2021) research programme funded by the Natural Environment Research Council (NERC). The aim of the research is to to advance the understanding of, and capability to predict, the Southern Ocean's impact on climate change via its uptake and storage of heat and carbon. The programme will significantly reduce uncertainties concerning how this uptake and storage by the ocean influences global climate, by conducting a series of unique fieldwork campaigns and innovative model developments.

Background

ORCHESTRA represents the first fully-unified activity by NERC institutes to address these challenges, and will draw in national and international partners to provide community coherence, and to build a legacy in knowledge and capability that will transcend the timescale of the programme itself.

It brings together science teams from six UK research institutions to investigate the role that the Southern Ocean plays in our changing climate and atmospheric carbon draw-down. It is led by British Antarctic Survey, in partnership with National Oceanography Centre, British Geological Survey, Plymouth Marine Laboratory, the Centre for Polar Observation and Modelling and the Sea Mammal Research Unit.

The oceans around Antarctica play a critical a key role in drawing down and storing large amounts of carbon and vast quantities of heat from from the atmosphere. Due to its remoteness and harsh environment, the Southern Ocean is the world's biggest data desert, and one of the hardest places to get right in climate models. The ORCHESTRA programme will make unique and important new measurements in the Southern Ocean using a range of techniques, including use of the world-class UK research vessel fleet, and deployments of innovative underwater robots. The new understanding obtained will guide key improvements to the current generation of computer models, and will enhance greatly our ability to predict climate into the future.

The scope of the programme includes interaction of the Southern Ocean with the atmosphere, exchange between the upper ocean mixed layer and the interior and exchange between the Southern Ocean and the global ocean.

Further details are available on the ORCHESTRA page.

Participants

Six different organisations are directly involved in research for ORCHESTRA. These institutions are:

• British Antarctic Survey (BAS)
• National Oceanography Centre (NOC)
• Plymouth Marine Laboratory (PML)
• British Geological Survey (BGS)
• Centre for Polar Observation and Modelling (CPOM)
• Sea Mammal Research Unit (SMRU)

GO-SHIP are a third party organisation that, although not directly involved with the programme, will conduct ship based observations that will also be used by ORCHESTRA.

Research details

Three Work Packages have been funded by the ORCHESTRA programme. These are described in brief below:

• Work Package 1: Interaction of the Southern ocean with the atmosphere
  WP1 will use new observations of surface fluxes and their controlling parameters in order to better constrain the exchanges of heat and carbon loss across the surface of the Southern Ocean.

• Work Package 2: Exchange between the upper ocean mixed layer and the interior.
  This work package will combine observationally-derived data and model simulations to determine and understand the exchanges between the ocean mixed layer and its interior.

• Work Package 3: Exchange between the Southern Ocean and the global ocean .
  This WP will use budget analyses of the hydrographic/tracer sections to diagnose the three-dimensional velocity field of the waters entering, leaving and recirculating within the Southern Atlantic sector of the Southern ocean.

• Fieldwork and data collection

  The campaign consists of 12 core cruises on board the NERC research vessels RRS James Clark Ross and RRS James Cook and will include hydrographic/tracer sections conducted across Drake Passage (SR1b), the northern Weddell Sea/Scotia Sea (A23), the northern rim of the Weddell Gyre (ANDREXII) and across the South Atlantic (24S). Section I6S will be performed by GO-SHIP Project Partners. Measurements will include temperature, salinity, dissolved oxygen, velocity, dissolved inorganic carbon, total alkalinity, inorganic nutrients, oxygen and carbon isotopes, and underway meteorological and surface ocean observations including pCO₂.

  Tags will be deployed on 30 Weddel seals and these will provide temperature and salinity profiles that can be used alongside the Argo data.

  Autonomous underwater ocean gliders will conduct multi-month missions and will deliver data on ocean stratification, heat content, mixed layer depth and turbulent mixing over the upper 1 km, with previously-unobtainable temporal resolution. These gliders will be deployed in the Weddell Gyre and the ACC.

  Field campaigns with the MASIN meteorological aircrafts will be conducted flying out of Rothera and Halley research stations and the Falkland Islands. These campaigns will deliver information on key variables relating to air-sea fluxes (surface and air temperature, wind, humidity, atmospheric CO₂, radiation, turbulent fluxes of heat, momentum and CO₂), in different sea ice conditions and oceanic regimes.

  Eart Observation datasets will be used to inform the programme on the properties of the ocean, sea ice and atmosphere and on interactions between them.

  A cluster of 6 deep ocean moorings in the Orkney Passage will collect year round series of AABW temperatre and transport. This work connects to the NERC funded project Dynamics of the Orkney Passage Outflow (DYNOPO).

  The UK Earth System model (UKESM) and underlying physical model will be used to conduct analyses of heat and carbon uptake and transport by the Southern Ocean and their links to wider climate on decadal timescales.

  An eddy-resolving (1/12°) sector model of the ocean south of 30°S with 75 vertical levels, will be built using the NEMO model coupled to the Los Alamos sea ice (CICE) model. The improvements on the ocean boundary layer will be based from the results from the NERC-funded OSMOSIS project and the inclusion of tides.

  20-5 year runs of an adjoint model will be conducted to determine how key forcings and model states affect the uptake and subduction of heat and carbon by the ocean.

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: