Date (Creation)

2020-07-01

Date (Revision)

2020-07-01

Date (Publication)

2020-07-01

Date (released)

2020-07-01

Edition

1.0

Unique resource identifier

https://doi.org/10.5285/81b419c4-0055-435a-9bed-f583f64bd25a

Codespace

doi

Unique resource identifier

GB/NERC/BAS/PDC/01361

Codespace

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

Other citation details

Please cite this item as: Jordan, T., Ferraccioli, F., Armadillo, E., & Bozzo, E. (2020). Processed line aerogravity data over Wilkes Subglacial Basin region (2005/06 season) (Version 1.0) [Data set]. UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation. https://doi.org/10.5285/81b419c4-0055-435a-9bed-f583f64bd25a

Credit

No credit.

Status

Completed

Point of contact

Organisation name	Individual name	Electronic mail address	Role
British Antarctic Survey	Jordan, Tom		Author
British Antarctic Survey	Ferraccioli, Fausto		Author
DISTAV, University di Genova, Genoa, Italy	Armadillo, Egidio		Author
DISTAV, Universita di Genova, Genoa, Italy	Bozzo, Emanuele		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 > Solid Earth > Geodetics/Gravity > Gravity

Theme

• Aerogeophysics

• Aerogravity

• Antarctica

Place

• Wilkes Subglacial Basin Antarctica

GEMET - INSPIRE themes, version 1.0

• Geology

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:

Jordan, T., Ferraccioli, F., Armadillo, E., & Bozzo, E. (2020). Processed line aerogravity data over Wilkes Subglacial Basin region (2005/06 season) (Version 1.0) [Data set]. UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation. https://doi.org/10.5285/81B419C4-0055-435A-9BED-F583F64BD25A

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.

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

url

Codespace

url

Association Type

Cross reference

Unique resource identifier

url

Codespace

url

Association Type

Cross reference

Spatial representation type

Text, table

Language

English

Character set

UTF8

Topic category

• Geoscientific information

Begin date

2005-12-04

End date

2006-01-25

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:

WISE-ISODYN aerogeophysics data presented in (Ferraccioli et al., 2009), further details on basic data acquisition are described in (Ferraccioli et al., 2007). The dataset available here includes channels from raw through to filtered and upward continued free air anomalies, where data was recoverable. Data processing steps are outlined below

Processing steps:

1/ Calculate observed gravity.

True spring tension (ST_real) is calculated from the posted spring tension (ST) correcting for the fact that for this survey the true spring tension approaches the posted value at 38 mGal per second.

Beam velocity (Beam_vel) is derived from raw beam position (RB) assuming a centred difference approximation.

Relative gravity (rec_grav) = (Spr_tens_real + ((beam_vel) * k_fac) + CC) * scale_value, k_fac = 30, meter scale value = 0.9966.

Still readings (Still) are in mGal and were calculating assuming a 2nd order best fit to the approximately linear drift of the meter observed at the tie down points.

Airborne absolute gravity values (Abs_grav) = Rec_grav - Still + Base

2/ Corrections to derive free air anomalies (disturbances).

Vertical acceleration (VaccCor) is calculated as 2nd derivative of flight altitude (Height_WGS1984), with a 3 point mean filter applied after differencing to reduce short wavelength noise.

Eotvos correction (EotvosCor) follows (Harlan, 1968).

Latitude correction (LatCor) = 978.03185(1+0.005278895 sin2Lat- 0.000023462 sin4Lat) (IUGG 1967).

Free air correction (FaCor) = 0.3086*Height_WGS1984. NOTE subsequent free air values are defined as gravity disturbances in geodesy, as they are referred to the ellipsoid (Hackney and Featherstone, 2003).

Horizontal acceleration correction (HaccCor). For this survey the approximation of (Swain, 1996) was used, assuming a damping factor of 0.707, and a platform period of 4 minutes.

3/ Free air anomaly and filtering.

Free air anomaly (Free_air) = Abs_grav-VaccCor+EotvosCor+FaCor-LatCor-(0.5*HaccCor)

Filtered free air anomaly (FAA_filt) used 9 km 1/2 wavelength space domain kernel filter (Holt et al., 2006).

Final free air data (FAA_clip) was produced by manually masking turns, start and end of lines, and other regions of noisy data.

Upward continued free air anomaly (Faacont) was produced by upward continuing free air data from the collected flight altitude to 2800 m.

Channel description:

Basic Channels

Date UTC date (YYYY/MM/DD)

Time UTC time (HH:MM:SS.SS)

FlightID Sequential flight number and survey ID e.g. W12

Line_name Line Number e.g. LW200.1:12

Lon Longitude WGS 1984, for processing see readme

Lat Latitude WGS 1984, for processing see readme

x x projected meters*

y y projected meters*

Height_WGS1984 Aircraft altitude (meters) in WGS 1984, for processing see location data page

Raw gravity Channels

ST Spring Tension (meter units)

CC Cross Coupling (meter units)

RB Raw beam position (Mv)

XACC Cross axis accelerometer (Mv)

LACC Long axis accelerometer (Mv)

Still Airborne meter still reading value (mGal)

Base Absolute gravity reference, from land gravity (mGal)

Calculation Channels

St_real True Spring tension value (meter units)

Beam_vel Gravity meter beam velocity (Mv/sec)

Rec_grav Recalculated relative gravity (mGal)

Abs_grav Calculated absolute gravity (mGal)

VaccCor Vertical acceleration correction

EotvosCor Eotvos correction

LatCor Latitude correction

FaCor Free air correction

HaccCor Horizontal acceleration correction

Free air Channels

Free_air Un-filtered free air anomaly (mGal)

FAA_filt Filtered free air anomaly (mGal)

FAA_clip Free air anomaly excluding turns/and climbs.

FAA_3750m Free air gravity anomaly upward continued to a uniform elevation of 3750 m.

*Projected coordinates (x and y) are in Lam...(4)

Metadata

File identifier

81b419c4-0055-435a-9bed-f583f64bd25a XML

Metadata language

English

Character set

UTF8

Hierarchy level

Dataset

Hierarchy level name

dataset

Date stamp

2020-07-01

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