Processed line aerogravity data over Northern Palmer Land, Antarctic Peninsula (2002/03 season)

Over 20,000 km of new aerogravity data were acquired over Palmer Land during the 2002-2003 Antarctic campaign. Profile lines were oriented E-W with N-S tie lines. Line spacing was 5 km, tie lines were 25 km apart and nominal flight altitude was 2800 m. Differential, carrier phase, kinematic GPS processing methods provided the vertical and horizontal accelerations, which dominate the raw aerogravity signal. Levelled airborne gravity data have mean accuracies of 3 mGal.

We present here the processed line aerogravity data collected using Lacoste and Romberg air-sea gravity meter S83.

Data are provided as XYZ ASCII line data.

Date (Creation): 2020-06-30

Date (Revision): 2020-06-30

Date (Publication): 2020-06-30

Date (released): 2020-06-30

Edition: 1.0

Unique resource identifier: https://doi.org/10.5285/5388db62-4a5e-4072-9b01-3a65785d80a0

Codespace: doi

Unique resource identifier: GB/NERC/BAS/PDC/01359

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

Other citation details: Please cite this item as: Jones, P., & Ferraccioli, F. (2020). Processed line aerogravity data over Northern Palmer Land, Antarctic Peninsula (2002/03 season) (Version 1.0) [Data set]. UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation. https://doi.org/10.5285/5388db62-4a5e-4072-9b01-3a65785d80a0

Credit: No credit.

Status: Completed

Point of contact

Organisation name	Individual name	Electronic mail address	Role
British Antarctic Survey	Jones, P.C.		Author
British Antarctic Survey	Ferraccioli, Fausto		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

Place

Northern Palmer Land Antarctica
Antarctic Peninsula Antarctica

GEMET - INSPIRE themes, version 1.0

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Other constraints: Open Government Licence v3.0

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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/

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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:

Jones, P. C., & Ferraccioli, F. (2020). Processed line aerogravity data over Northern Palmer Land, Antarctic Peninsula (2002/03 season) (Version 1.0) [Data set]. UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation. https://doi.org/10.5285/5388DB62-4A5E-4072-9B01-3A65785D80A0

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.

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Spatial representation type: Text, table

Language: English

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Geoscientific information

Begin date: 2002-12-26

End date: 2003-01-13

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

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Organisation name	Individual name	Electronic mail address	Role
NERC EDS UK Polar Data Centre		PDCServiceDesk@bas.ac.uk	Distributor

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OnLine resource

Protocol	Linkage	Name
WWW:LINK-1.0-http--link	https://ramadda.data.bas.ac.uk/repository/entry/show?entryid=5388db62-4a5e-4072-9b01-3a65785d80a0	Get Data

Hierarchy level: Dataset

Statement: Methodology:

SPARC airborne gravity data and details of survey design and data processing are presented in Ferraccioli et al (2006).

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

Faa Un-filtered free air anomaly

FAAup Upward continued free air anomaly to altitude 2800 m

*Projected coordinates (x and y) are in Polar stereographic defined as follows:

Latitude of natural origin: -71

Longitude of natural origin: 0

Scale factor at natural origin -75.33333333333

False easting 0

False northing 2...(4)

Metadata

File identifier: 5388db62-4a5e-4072-9b01-3a65785d80a0 XML

Metadata language: English

Character set: UTF8

Hierarchy level: Dataset

Hierarchy level name: dataset

Date stamp: 2020-06-30

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

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