Date (Creation)

2021-06-30

Date (Revision)

2021-06-30

Date (Publication)

2021-06-30

Date (released)

2021-06-30

Edition

1.0

Unique resource identifier

https://doi.org/10.5285/c7ea5697-87e3-4529-a0dd-089a2ed638fb

Codespace

doi

Unique resource identifier

GB/NERC/BAS/PDC/01515

Codespace

https://data.bas.ac.uk/

Other citation details

Please cite this item as: Corr, H. (2021). Processed airborne radio-echo sounding data from the GRADES-IMAGE survey covering the Evans and Rutford Ice Streams, and ice rises in the Ronne Ice Shelf, West Antarctica (2006/2007) (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/c7ea5697-87e3-4529-a0dd-089a2ed638fb

Credit

No credit.

Status

Completed

Point of contact

Organisation name	Individual name	Electronic mail address	Role
British Antarctic Survey	Corr, Hugh		Author
NERC EDS UK Polar Data Centre		PDCServiceDesk@bas.ac.uk	Point of contact

Maintenance and update frequency

As needed

Maintenance note

Completed

Global Change Master Directory (GCMD) Science Keywords

• EARTH SCIENCE > Cryosphere > Glaciers/Ice Sheets > Glacier Elevation/Ice Sheet Elevation
• EARTH SCIENCE > Cryosphere > Glaciers/Ice Sheets > Glacier Thickness/Ice Sheet Thickness
• EARTH SCIENCE > Cryosphere > Glaciers/Ice Sheets > Glacier Topography/Ice Sheet Topography
• EARTH SCIENCE > Spectral/Engineering > Radar > Radar Imagery
• EARTH SCIENCE > Cryosphere > Glaciers/Ice Sheets

Theme

• Antarctic

• aerogeophysics

• ice thickness

• radar

• surface elevation

Place

• Ronne Ice Shelf Antarctica

GEMET - INSPIRE themes, version 1.0

• Elevation

Access constraints

Other restrictions

Other constraints

no limitations to public access

Access constraints

Other restrictions

Other constraints

no limitations

Use constraints

License

Other constraints

Open Government Licence v3.0

Use constraints

Other restrictions

Other constraints

This data is governed by the NERC Data Policy: https://www.ukri.org/who-we-are/nerc/our-policies-and-standards/nerc-data-policy/

Use constraints

Other restrictions

Other constraints

. Further by downloading this data the user acknowledges that they agree with the NERC data policy (), and the following conditions:

1. To cite the data in any publication as follows:

Corr, H. (2021). Processed airborne radio-echo sounding data from the GRADES-IMAGE survey covering the Evans and Rutford Ice Streams, and ice rises in the Ronne Ice Shelf, West Antarctica (2006/2007) (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/C7EA5697-87E3-4529-A0DD-089A2ED638FB

2. The user recognizes the limitations of data. Use of the data is at the users' own risk, and there is no warranty as to the quality or accuracy of any data, or the fitness of the data for your intended use. The data are not necessarily fully quality assured and cannot be expected to be free from measurement uncertainty, systematic biases, or errors of interpretation or analysis, and may include inaccuracies in error margins quoted with the data.

Use constraints

Other restrictions

Other constraints

None

Unique resource identifier

url

Codespace

url

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Spatial representation type

Text, table

Language

English

Character set

UTF8

Topic category

• Elevation
• Geoscientific information

Begin date

2006-12-29

End date

2007-01-30

Supplemental Information

It is recommended that careful attention be paid to the contents of any data, and that the author be contacted with any questions regarding appropriate use. If you find any errors or omissions, please report them to polardatacentre@bas.ac.uk.

Title

European Petroleum Survey Group (EPSG) Geodetic Parameter Registry

Date (Publication)

2008-11-12

Cited responsible party

Organisation name	Individual name	Electronic mail address	Role
European Petroleum Survey Group		EPSGadministrator@iogp.org	Publisher

Unique resource identifier

urn:ogc:def:crs:EPSG::3031

Version

6.18.3

Hierarchy level

Dataset

Statement

Methodology:

** Instrumentation and Processing:

Radar data were collected using the bistatic PASIN radar echo sounding system mounted on the BAS Twin Otter aircraft "Bravo Lima" and operating with a centre frequency of 150 MHz and using two interleaved pulses: a 4-microseconds, 10 MHz bandwidth linear chirp (deep sounding) and a 0.1-microseconds unmodulated pulse (shallow sounding).

Chirp compression was applied using a Blackman window to minimise sidelobe levels, resulting in a processing gain of 10 dB. The chirp data was processed using an coherent averaging filter (commonly referred to as unfocused Synthetic Aperture Radar (SAR) processing) along a moving window of length 15. This product is best used to assess the bed and internals in deep ice conditions. The pulse data was processed using an incoherent averaging filter along a moving window of length 25 and using a combination of the upper and lower channels. This data is best used to assess the internal structure and bed in shallow ice conditions.

The bed reflector was first automatically depicted on the chirp data using a semi-automatic picker in the PROMAX software package. All the picks were afterwards checked and corrected by hand if necessary. The picked travel time was then converted to depth using a radar wave speed of 168 m/microseconds and a constant firn correction of 10 m. Surface elevation is derived from radar altimeter for ground clearance < 750 m, and the PASIN system for higher altitudes.

** Coordinates and Positions:

The coordinates provided in the NetCDF for the surface and bed elevation for each radar trace are in longitude and latitude (WGS84, EPSG: 4326). The navigation attributes for the radar data in the NetCDF are in projected X and Y coordinates (Polar Stereographic, EPSG: 3031), as follows:

Latitude of natural origin: -71

Longitude of natural origin: 0

Scale factor at natural origin: 0.994

False easting: 0

False northing: 2082760.109

The coordinates in the SEGY data are also in projected X and Y coordinates (Polar Stereographic, EPSG: 3031), although note that these are in integer format due to the SEGY limitations (see section below).

Positions are calculated for the phase centre of the aircraft antenna. All positions (Longitude, Latitude and Height) are referred to the WGS1984 ellipsoid.

** Dataset:

Please note: Due to the unstable nature of SEGY-formatted data and its uncertain long-term future, as well as the issues documented below, we also provide the full radar data in NetCDF format. The dataset provided here consists of three parts: a NetCDF file per flightline, two SEGY files per flightline (one chirp and one pulse), and one quicklook PDF file per flightline. These are described in more details below.

- NetCDF: The NetCDF files contain the deep-sounding chirp and shallow-sounding pulse-acquired data in their processed form, as well as the associated metadata, navigational information (in both EPSG: 3031 and WGS84 EPSG: 4326), and the associated radar-related information for each trace (e.g. surface/bed elevation and picks, ice thickness, aircraft altitude, range to surface, time of trace) which are provided as separate attributes in the NetCDF file. The navigational position of each trace comes from the surface files, and the processed GPS files when no surface information was provided in the surface files. Note that for these, interpolation of the navigational data might have been required to match closely the Coordinated Universal Time (UTC) of each trace in the surface files. No data is shown as "-9999" throughout the files.

NetCDF attributes:

- 'traces': Trace number for the radar data (x axis)

- 'fast_time': Two-way travel time (y axis) (units: microseconds)

- 'x_coordinates': Cartesian x-coordinates for the radar data (x axis) (units: meters in WGS84 EPSG:3031)

- 'y_coordinates': Cartesian y-co...(53)

Data collection:

** Instrument:

Radar data were collected using the bistatic PASIN (Polarimetric radar Airborne Science Instrument) radar echo sounding system mounted on the BAS Twin Otter aircraft "Bravo Lima" and operating with a centre frequency of 150 MHz and using two interleaved pulses: a 4-microseconds, 10 MHz bandwidth linear chirp (deep sounding) and a 0.1-microseconds unmodulated pulse (shallow sounding). The Pulse Repetition Frequency was 15,635 Hz (pulse repetition interval: 64 microseconds).

** Antenna configuration:

8 folded dipole elements:

4 transmitters (port side)

4 receivers (starboard side)

Antenna gain: 11 dBi (with 4 elements)

Transmit power: 1 kW into each 4 antennae

Maximum transmit duty cycle: 10% at full power (4 x 1 kW)

** Radar receiver configuration:

Receiver vertical sampling frequency: 22 MHz (resulting in sampling interval of 45.4546 ns)

Receiver coherent stacking: 25

Receiver digital filtering: -50 dBc at Nyquist (11 MHz)

Effective PRF: 312.5 Hz (post-hardware stacking)

Sustained data rate: 10.56 Mbytes/second

Data quality:

- Trace spacing (post-processed data): ~20 m

- Vertical resolution: ~8.4 m

- Radar centre frequency: 150 MHz

- Radar bandwidth: 10 MHz

- Radar Receiver vertical sampling frequency: 22 MHz

- Absolute GPS positional accuracy: ~0.1 m (relative accuracy is one order of magnitude better). Banking angle was limited to 10 deg during aircraft turns to avoid phase issues between GPS receiver and transmitter.

Please note: The surface and bed pick information (surface and bed elevation, ice thickness, etc.) can also be found at: https://doi.org/10.5285/4efa688e-7659-4cbf-a72f-facac5d63998.The datasets found here have been considerably curated and improved, and thus can be considered the latest and full dataset .

Metadata

File identifier

c7ea5697-87e3-4529-a0dd-089a2ed638fb XML

Metadata language

English

Character set

UTF8

Hierarchy level

Dataset

Hierarchy level name

dataset

Date stamp

2021-06-30

Metadata standard name

ISO 19115 Geographic Information - Metadata

Metadata standard version

ISO 19115:2003(E)

Metadata author

Organisation name	Individual name	Electronic mail address	Role
NERC EDS UK Polar Data Centre		polardatacentre@bas.ac.uk	Point of contact