Date (Creation)

2021-10-12

Date (Revision)

2021-10-12

Date (Publication)

2021-10-12

Date (released)

2021-10-12

Edition

1.0

Unique resource identifier

https://doi.org/10.5285/0cb61583-3985-4875-b141-5743e68abe35

Codespace

doi

Unique resource identifier

GB/NERC/BAS/PDC/01571

Codespace

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

Unique resource identifier

NE/L013770/1

Codespace

award

Other citation details

Please cite this item as: Corr, H., Robinson, C., Jordan, T., Nicholls, K., & Brisbourne, A. (2021). Processed airborne radio-echo sounding data from the FISS 2016 surveys covering the Filchner and Halley Ice Shelves, and the English Coast (western Palmer Land), West Antarctica (2016/2017) (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/0cb61583-3985-4875-b141-5743e68abe35

Credit

No credit.

Status

Completed

Point of contact

Organisation name	Individual name	Electronic mail address	Role
British Antarctic Survey	Corr, Hugh		Author
British Antarctic Survey	Robinson, Carl		Author
British Antarctic Survey	Jordan, Tom		Author
British Antarctic Survey	Nicholls, Keith		Author
British Antarctic Survey	Brisbourne, Alex		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 > Cryosphere > Glaciers/Ice Sheets
• EARTH SCIENCE > Spectral/Engineering > Radar

Theme

• Antarctic

• aerogeophysics

• ice thickness

• radar

• surface elevation

Place

• Filchner Ice Shelf Antarctica

• English Coast of western Palmer Land Antarctica

• Halley 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., Robinson, C., Jordan, T., Nicholls, K., & Brisbourne, A. (2021). Processed airborne radio-echo sounding data from the FISS 2016 surveys covering the Filchner and Halley Ice Shelves, and the English Coast (western Palmer Land), West Antarctica (2016/2017) (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/0CB61583-3985-4875-B141-5743E68ABE35

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

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

url

Codespace

url

Association Type

Larger work citation

Unique resource identifier

url

Codespace

url

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

2016-12-15

End date

2017-01-22

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 new bistatic PASIN-2 radar echo sounding system mounted on the BAS Twin Otter aircraft "VP-FBL" and operating with a centre frequency of 150 MHz and using a 4-microseconds, 13 MHz bandwidth linear chirp.

The three surveys all varied slightly in terms of radar configuration, with FISS being configured as a 12-element swath radar, Halley configured as three distinct antenna groups with different gains to cater for the awkward Brunt ice, and the English Coast configured as a polarimetric radar. More information on the antennae configuration can be found in the 'Data Collection' section further down this page. Note that flights F02-18 were flown as part of the FISS survey, flights F19-23 were flown over the Halley Ice Shelf, and flights F25-31 were flown over the English Coast (western Palmer Land).

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 a coherent averaging filter (commonly referred to as unfocused Synthetic Aperture Radar (SAR) processing) with Doppler beam sharpening to enhance the signal to clutter ratio of the bed echo and improve visualisation. The received chirp of 4 microseconds, 13 MHz bandwidth data was compressed, filtered, and decimated from the original trace acquisition rate of 125 Hz to 5Hz, equivalent to ~11m in along-track spacing. The chirp data is best suited to assess the bed and internals in deep ice conditions. The coherent pulse-data (0.1-microseconds) was processed using a coherent averaging filter. 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. Where possible, the ice surface location within the radargrams was calculated using lidar measurements of surface elevation. In areas where lidar data was not available, the location of the surface reflection was picked directly from the radargram. The origin of the elevation measurement can be found in the 'surface_source_layerData' variable in this NetCDF, and is composed of either: 0 = LIDAR, 1 = interpolated LIDAR for gaps ~55 m, 2 = radar.

Note: Flights F21-22 and F31 contain no bed/surface pick or elevation information (such as surface/bed elevation/aircraft elevations, ice thickness, etc). Flights F19-20 and F30 contain bed/surface pick but no elevation data. Note also that flight F31 only contain the shallow-sounding pulse data.

** 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.

Note: The PriNumber in both chirp and pulse SEGY differs, however the trace number and time of each trace is the same for both radar variables. We have therefore provided 2x NetCDF variables for the PriNumber in case this is nee...(80)

Data collection:

** Instrument:

Radar data were collected using the bistatic PASIN-2 (Polarimetric radar Airborne Science Instrument 2) radar echo sounding system mounted on the BAS Twin Otter aircraft "VP-FBL" and operating with a centre frequency of 150 MHz and using a pulse-coded waveform at an effective acquisition rate of 312.5 Hz and a bandwidth of 13 MHz. The Pulse Repetition Frequency was 15,625 Hz (pulse repetition interval: 64 microseconds).

** Antenna configuration:

8 transmitters (4x port side and 4x starboard side)

12 receivers (8x wings and 4x belly)

Transmit power: 1 kW into each antennae

Maximum transmit duty cycle: 10% at full power

FISS: 12x channel swatch radar (8x transmit, 12x receive)

Halley: Similar to FISS but with 30dB attenuation in the receive path for the starboard antennae to accommodate for varying ice conditions around the Brunt Ice Shelf.

English Coast: Full polarimetric mode

** Waveform details

FISS: Five waveforms, 4uS Tukey port, 4us Tukey starboard, 4uS Tukey (180deg out of phase) port, 4 uS Tukey (180deg out of phase) starboard, 1 uS Tukey antenna 1 (port).

Halley: Five waveforms, 4uS Tukey port, 4uS Tukey starboard, 4 uS Tukey (180deg out of phase) port, 4 uS Tukey (180deg out of phase) starboard, 1 uS Tukey antenna 1 (port). Starboard 30dB attenuation on RX.

English Coast: Five waveforms, 4uS Tukey port, 4uS Tukey starboard, 4 uS Tukey (180deg out of phase) port, 4 uS Tukey (180deg out of phase) starboard, 1 uS Tukey antenna 1 (port). Port antennas rotated.

** 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: 125 Hz (post-hardware stacking)

Sustained data rate: 10.56 Mbytes/second

Data quality:

- Average spacing between radar traces: 11 m

- Line spacing: ~3.5-km (English Coast)

- Radar centre frequency: 150 MHz

- Radar bandwidth: 13 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 degrees during aircraft turns to avoid phase issues between GPS receiver and transmitter.

Note: The SEGY and bed pick files for the English Coast section of the FISS 2016/17 surveys can also be found at: https://doi.org/10.5285/e07d62bf-d58c-4187-a019-59be998939cc. However note that the SEGY data found there is not georeferenced. The datasets found here have been considerably curated and improved, and thus can be considered the latest and full dataset .

Metadata

File identifier

0cb61583-3985-4875-b141-5743e68abe35 XML

Metadata language

English

Character set

UTF8

Hierarchy level

Dataset

Hierarchy level name

dataset

Date stamp

2021-10-12

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