Metadata Report for BODC Series Reference Number 1918981

• 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 EM122 12kHz Multibeam Echosounder

The EM122 is designed to perform seabed mapping to full ocean depth with a high resolution, coverage and accuracy. Beam focusing is applied both during reception and transmission. The system has up to 288 beams/432 soundings per swath with pointing angles, which are automatically adjusted according to achievable coverage or operator defined limits.

This model uses both Continuous Wave and Frequency Modulated sweep pulses with pulse compression on reception, in order to increase the maximum useful swath width. The transmit fan is split in several individual sectors, with independent active steering, in order to compensate for the vessel movements.

In multiplying mode, two swaths per ping cycle are generated, with up to 864 soundings. The beam spacing is equidistant or equiangular and the transmit fan is duplicated and transmitted with a small difference in along track tilt, which takes into account depth coverage and vessel speed, to give a constant sounding separation along track. In high density mode, more than one sounding per beam can be produced, such that horizontal resolution is increased and is almost constant over the whole swath.

The EM122 transducers are modular linear arrays in a Mills cross configuration with separate units for transmit and receive. If used to deliver sub-bottom profiling capabilities with a very narrow beamwidth, this system is known as SBP120 Sub-Bottom Profiler.

The specification sheet can be accessed here Kongsberg EM122.

Specifications

EM122 versions

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.

Furuno GPS/WAAS Navigator GP32

The GP32 is an advanced GPS navigator with a Wide Area Augmentation System (WAAS) receiver which can receive up to 12 discrete GPS channels, all-in-view, and also has DGPS capabilities.

The WAAS applies correction data by means of geostationary satellites. The reference stations on earth monitor the GPS constellation and route GPS error data to the WAAS satellite via the master earth station.

This equipment is comprised of a compact unit designed for coastal activities with several display modes, e.g. Plotter, Nav Data, Steering, Highway, Speedometer and two other costumisable modes. The data can be viewed in WGS-84 or other geodetic systems.

Specifications

The equipment's specification sheet can be accessed Furuno GP32

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.

BAS_PSPE RRS James Clark Ross Cruise JR20110128 (JR244) Underway Navigation Instrumentation Document

The navigation instruments used to collect this data set are presented in the table below. Although several GPS systems were collecting data, only latitude and longitude from the Furuno is included in the final.

BAS_PSPE RRS James Clark Ross Cruise JR20110128 (JR244) Underway Navigation Processing Procedures Document

Originator's Data Processing

The processing procedures, throughout the cruise, consisted of data retrieval from the previous 24h and logging those into subdirectories on the ship's intranet system.

Navigation instruments were located on the ship's monkey island, above the bridge.

Data processing was carried out at BAS on selected data streams. The ship has four positioning systems, but as the Seatex GPS provides the input latitude and longitude for the multibeam positioning, it is considered as a primary source of data, so processing was carried out on this stream but not on the others. These procedures included:

• check for duplicate dates and times
• standardising time
• check for gaps in data
• check data against defined thresholds
• interpolation and flagging
• unit conversion

The originator sent two files with processed ship's heading and position data and bathymetry was retreived from the raw files.

Files delivered to BODC

BODC Data Processing

The files mentioned above were selected for data banking as they contain the best version of unprocessed position, heading and bathymetry. Data were banked at BODC following standard data banking procedures, including reduction through averaging, checking navigation channels for improbable values, working out speed over ground, and screening the data for anomalous values.

The originator's variables were mapped to appropriate BODC parameter codes as follows:

jr244_furuno_exactsec

The file also contained vn, ve, cmg, smg, dist_run and heading_av, however these parameters were not transferred as they were derived by the originator or could be extracted from a more accurate source.

jr244_gyro_exactsec

em120

Screening

All the reformatted data were visualised using the in-house EDSERPLO software. Improbable data were marked by adding an appropriate quality control flag, missing data by both setting the data to an appropriate value and applying the quality control flag.

Position

A check was run on the position data gaps were identified. These gaps were corrected by linear interpolation.

Ship's velocities

Ship's eastward and northward velocities were calculated from the main latitude and longitude channels.

Distance Run

Distance run was calculated from the main latitude and longitude channels, starting from the beginning of the cruise. The channel has several M flags but these were applied to the same cycles where ALATGP01 and ALONGP01 were flagged by the originator. The channel is regular with no jumps or gaps.

Bathymetry

Bathymetry data from both the echosounder and multibeam were loaded and screened. In general, the multibeam bathymetry has a better quality, however both periods exhibit some periods with suspect data. Both channels were flagged where data were considered improbable. Only the multibeam bathymetry data are included in the final file. Users should use caution when interpreting the bathymetric depth channel.

Project Information

Polar Science for Planet Earth (PSPE)

Introduction

The PSPE programme is the British Antarctic Survey strategic science framework that extends from April 2009 to March 2013. This programme was created to respond to the Natural Environment Research Council (NERC) strategy from 2007 to 2012, and contributes to a major environmental research programme, Living with Environmental Change (LWEC), which comprises a 10 year partnership between the UK's main organisations that fund, carry out and use environmental research and observations and will improve the country's tools and knowledge to build resilience, mitigate problems and adapt to environmental change.

The PSPE programme will focus on key questions that can be answered by research requiring access to the polar regions, developing research and long term monitoring and survey programmes in the Antarctic but also pursuing new bi-polar and Arctic research opportunities. The support given to the research programmes includes: investment in training, development of scientific skills and expertise, maintenance of the existing research infrastructures (research stations, ships, aircraft and laboratories), development of new techniques to collect, transfer, curate and visualize data from and relating to the polar regions.

PSPE consists of 6 programmes:

• Climate: atmospheric science and processes, including climate modelling
• Chemistry and past climate: quaternary climate including ice cores, lake, sediments, marine sediments and tropospheric chemistry
• Ecosystems: dynamics of polar ecosystems in response to the impacts of climate and fisheries
• Environmental Change and Evolution: the Earth system; geological to upper atmosphere, complexities and scales of interactions, controls on biological evolution
• Ice sheets: ice sheet evolution and flow, ice sheet changes and sea level rise
• Oceans: role of the polar oceans in controlling and influencing the Earth system

Data Availability

The data produced during this project are available to the academic community.

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: