Metadata Report for BODC Series Reference Number 1759843

• 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

iSTAR RRS James Clark Ross Cruise JR20140126 (JR294, JR295) Underway Document

Cruise details

The cruise is part of the Ice Sheet Stability prgramme (iSTAR) which aims to investigate the ocean processes that are thought to enhance melting of the Pine Island Glacier in the Amundsen Sea. The cruise includes two NERC-funded ISTAR projects. ISTAR A, or Ocean2ice, supports a consortium led by UEA and addresses processes at the continental shelf break and on the continental shelf that affect the heat delivered to the ice shelf front, together with the subsequent fate of the ice shelf meltwater. The second is ISTAR B, led by BAS, which addresses the processes that affect the warm water once it has entered the ice shelf cavity.

The ship departed Punta Arenas, Chile, on 26 January 2014 and docked in Rothera on 8 March 2014 where the scientific crew desimbarked. The data submitted to BODC covers a period from 20 January 2014 to 04 March 2014, which includes the whole cruise period, plus transit from Punta Arenas and to Rothera. The extra days of data will not be included in the final file.

Delays in the planned work were mainly due to weather conditions rangin from stormy seas to fog and ice floes which prevented the ship from progressing at normal speed.

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

Ashtech GG24 receiver

The GG24 is an all-in-view Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) receiver that blends GPS and GLONASS into a single position solution. This receiver uses all available satellites from both systems to obtain the best position information.

The three-dimensional position and velocity are calculated when tracking any combination of five satellites. Up to five independent measurements are determined every second, with no interpolation or extrapolation from previous solutions.

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.

Kongsberg Seatex Seapath 200 GPS and Gyrocompass

The Seapath 200 is a highly accurate, real-time heading, attitude and position information system that integrates the best signal characteristics of Inertial Measurement Units (IMU) and Global Positioning System (GPS), using a differential GPS method to acquire this data.

The high-rate motion data is obtained from the Seatex MRU5 inertial sensor and two fixed baseline GPS carrier-phase receivers. The raw data is integrated in a Kalman filter in the Seapath Processing Unit. The IMU contains an accurate linear accelerometer and Bosch Coriolis force angular rate gyros (CFG).

This system is equipped to utilise up to six different DGPS reference stations, it checks for consistency within measurements from the different sensors to ensure reliability and rejects noisy data or reports its inaccuracy. The data is available through various output protocols, RS-232, RS-422 and Ethernet.

This instrument is no longer in production; the main characteristics are presented below, and the specification sheet can be accessed here Kongsberg Seatex Seapath 200 .

Specifications

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.

iSTAR RRS James Clark Ross Cruise JR20140126 (JR294, JR295) Underway Navigation Document

Content of data series

Instrumentation

The table below contains the navigation instruments used on board the ship and their main roles.

Data Processing Procedures

Originator's Data Processing

Surface hydrography, navigation and meteorological data were recorded throughout the cruise using an automated Matlab script. All data collection and processing was performed automatically by a procedure that triggers processing and then copies the resulting matlab dataset and figures to a shared drive. The main matlab script queries the SCS data streams provided by the JCR and imports the data into matlab, concatenating with data from previous previous days. The matlab script then proceeds to calculate additional variables before plotting each variable both as crude track maps and timeseries for rapid data visualisation and organising the data in a structure format.

The originator's file contains 5 substructures, flag (which contains a flag indicating potential issues with the raw data), clean (contains the raw data with all values flagged replaced by NaN), info (contains general file metadata), scripts (text conpies of the scripts for redeploying in future cruises) and raw (raw data with no quality control information.

One file, in matlab format, was submitted to BODC and contains all the variables for the three data types, Navigation, Meteorology and Surface Hydrography. Sampling frequency of the submitted data was of 60 seconds. Bathymetry data were not processed by the originator, so the raw data, was used instead.

Positioning instruments were located on the ship's monkey island, above the bridge, both the echosounder and swath were located on the ship's hull and the gyrocompass on the bridge.

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:

Oceanlogger.mat

The file also contain ship's speed, which was not transferred as it is a derived measurement. Ship's eastward and northward velocities were recalculated at BODC following standard procedures. Additionally the file contaied meteorological and surface hydrography parameters, which will be dealt with in the appropriate documentation.

ea600.ACO

em122.ACO

All 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.

MABNZZ01 is not included in the final file but it available upon request.

Position

A check was run on the position data and no gaps were identified. All data from 04 march 2014 16:08:59 hours to 04 March 2014 16:51:00 were null, so won't be included in the final file.

Ship's velocities

Ship's eastward and northward velocities were calculated from the main latitude and longitude channels. no issues were found with these channels.

Distance run

Distance run was calculated from the main latitude and longitude channels, starting from the beginning of the file.

Bathymetry

Bathymetry data from both the echosounder and multibeam were loaded and screened. GEBCO data were also loaded to provide guidance, but it was found to be almost entirely interpolated, thus it was decided to not use it as a guide to screening. In general the swath MBANSWCb exhibits better quality, however both channels were flagged for suspect data and users should use caution when interpreting the depth data channels.

Calibration

No information on calibrations against independent measurements were provided to BODC.

Quality control report

Several M flags were applied to MBANZZ01 when values were zero or considered improbable when screening against MBANSWCB.

M flags were also applied to MBANSWCB when improbable data was identified.

Problem report

No problems with the data were identified either by the originator or during BODC procedures.

Project Information

The Ice Sheet Stability (iSTAR) programme

Background and objectives

The iSTAR programme aims to measure the rate that ice is being lost from the West Antarctic ice sheet, and to improve our understanding of what might be driving this loss how it is changing over time. The rate of loss of water from ice in glaciers in the Antarctic (and Greenland) is more than the amount of water being deposited in these areas by precipitation. This has changed our understanding of these systems and the rate of ice loss is a matter of interest for sea level and climate research. Improving our understanding of the processes and impacts of changes to these systems is vital for better predictions for sea level rise in the future and will feed in to climate research. This programme combines scientific research of glaciers and the surrounding ocean environment (including how they impact each other). Research about the oceans was focused on the Amundsen Sea Sector of West Antarctica with instruments deployed from the research ship RRS James Clark Ross. Research about the ice was focused on Pine Island Glacier, Thwaites Glacier and Union Glacier with measurements taken during two expeditions across the ice. This programme was funded by the Natural Environment Research Council (NERC)

The programme is split in to four projects:

Ocean2ice: Processes and variability of ocean heat transport toward ice shelves in the Amundsen Sea Embayment (iSTAR A)

Ocean under ice: Ocean circulation and melting beneath the ice shelves of the south-eastern Amundsen Sea (iSTAR B)

Dynamic ice: Dynamical control on the response of Pine Island Glacier (iSTAR C)

Ice loss: The contribution to sea-level rise of the Amundsen Sea sector of Antarctica (iSTAR D)

Participants

The iSTAR research programme is managed by British Antarctic Survey (BAS) on behalf of NERC. Operational support, in the form of logistics planning and infrastructure, and Communication and Knowledge Exchange support are provided by BAS. There are four science projects and participants in these projects represent the following organisations:

• British Antarctic Survey
• National Oceanography Centre
• Newcastle University
• Scott Polar Research Institute
• University College London
• University of Bristol
• University of East Anglia
• University of Edinburgh
• University of Leeds
• University of Southampton
• University of St. Andrews
• University of Tasmania
• University of Washington

Fieldwork and data collection

A wide range of data parameters were collected for this programme. Physical and chemical measurements of the ocean close to and next to the ice shelf were made using instruments deployed from ship, on moorings, on autonomous platforms and seal tags. Measurements were also made of the glaciers and ice shelfs including radar and seismic surveys and ice cores. There were also meteorological and atmospheric measurements taken. For more information about the data collected on each of the four projects see the project web pages.

Data management

Data management for ocean data will be done by the British Oceanographic Data Centre whilst ice data will be managed by the Polar Data Centre.

For more information about iSTAR programme see the: iSTAR Programme Website

Ocean2ice: Processes and variability of ocean heat transport toward ice shelves in the Amundsen Sea Embayment (iSTAR A)

Background and objectives

Ocean2ice (otherwise referred to as iSTAR A) is a project that is part of NERC's Ice Sheet Stability programme. The project was designed to investigate how relatively warm water gets close to and beneath glaciers in the Antarctic and what impact this warm water has on the rate of ice melt at these sites. This research and collection of data will to feed in to climate and sea level forecasting and research. This project was funded by the Natural Environment Research Council.

Participants

The principal investigator for the Ocean2ice project is Professor Karen Heywood, University of East Anglia. Other participants in the project represent the following organisations:

• British Antarctic Survey
• National Oceanography Centre
• University of East Anglia
• University of Southampton
• University of St. Andrews

Fieldwork and data collection

Oceanographic data were collected from a wide range of instruments from the research ship RRS James Clark Ross between 26 January and 08 March 2014 in the Amundsen Sea. Data collected include measurements of the physical conditions (including temperature and salinity), current speeds and directions, chemical measurements of the water column (including oxygen and chlorophyll-a concentrations). A fleet of Seagliders (ocean robots that measure physical parameters including temperature, salinity and current speeds and directions) were also deployed to measure conditions close to the ice shelf. Moorings were deployed by the project and have measured conditions in the area over a couple of years. In addition Seal tags (small sensors glued to the fur of seals which fall off when the seals moult their fur) were deployed and transmit data back via satellite networks to scientists. These seal tag deployments give the scientists the rare opportunity to measure water properties below the ice shelf.

Data management

All data collected by the Ocean2ice project are to be submitted to the British Oceanographic Data Centre for careful storage, quality control, archiving and distribution to scientists, education, industry and the public.

For more information about Ocean2ice see the iSTAR A project page

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: