Long-range airborne geophysical measurements were carried out in the ICEGRAV campaigns (2010-2013), covering hitherto unexplored parts of interior East Antarctica and part of the Antarctic Peninsula. The airborne surveys provided a regional coverage of gravity, magnetic and ice-penetrating radar measurements for major Dronning Maud Land ice stream systems, from the grounding lines up to the Recovery Lakes drainage basin, and filled in major data voids in Antarctic data compilations.We present here the processed line aerogravity data collected using a LaCoste & Romberg air-sea gravity meter S83 mounted in the BAS aerogeophysically equipped Twin Otter aircraft.
Data are provided as XYZ ASCII line data.
Aerogeophysical, Antarctic, Gravity
|ISO Topic Categories:||
|Reference:||Exploring the Recovery Lakes region and interior Dronning Maud Land, East Antarctica, with airborne gravity, magnetic and radar measurements. Rene Forsberg, Arne V. Olesen, Fausto Ferraccioli, Tom A. Jordan, Kenichi Matsuoka, Andres Zakrajsek, Marta Ghidella and Jamin S. Greenbaum. Geological Society, London, Special Publications, 461, 20 September 2017, https://doi.org/10.1144/SP461.17
Hackney, R.I. & Featherstone, W.E., 2003. Geodetic versus geophysical perspectives of the gravity anomaly, Geophys. J. Int., 154, 35-43.
Holt, J.W., Richter, T.G., Kempf, S.D. & Morse, D.L., 2006. Airborne gravity over Lake Vostok and adjacent highlands of East Antarctica, Geochem. Geophys. Geosyst., 7, doi:10.1029/2005GC001177.
|Lineage:||The dataset available here includes all channels from raw through to filtered and upward continued free air anomalies. Only line sections with usable data are presented in the line by line database.
Raw data from L&R meter #S83 includes:
Channel names in brackets
Spring tension (ST) meter units
Cross coupling (CC) meter units
Raw beam position (RB) mV
Cross axis accelerometer output (XACC) mV
Long Axis accelerometer output (LACC) mV
Gravity processing steps were as follows:
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 40 mGal per second.
Beam velocity (Beam_vel) is derived from raw beam position (RB) assuming a centred difference approximation.
Relative gravity (rec_grav) = ((ST_real+CC)*0.9966)+(Beam_velocity*k_fac), k_fac=60/2.04, meter scale value =0.9966.
Still readings are in mGal (Still), and were calculated assuming a linear best fit to the drift of the airborne meter observed at the start and end of every flight. Tie absolute gravity values for the survey (Base) were derived from land gravity measurements adjacent to the survey aircraft tied back to the gravity base station at Rothera Research Station.
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)
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)
Final free air data (FAA_clip) was produced by manually masking turns, start and end of lines, and other regions of noisy data.
Note no levelling has been applied to the free air gravity data.
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
Lat Latitude WGS 1984
x x projected meters*
y y projected meters*
Height_WGS1984 Aircraft altitude (meters) in WGS 1984
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)
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 (mGal)
EotvosCor Eotvos correction (mGal)
LatCor Latitude correction (mGal)
FaCor Free air correction (mGal)
HaccCor Horizontal acceleration correction (mGal)
Free air Channels
Free_air Un-filtered free air anomaly (mGal)
FAA_clip Filtered free air anomaly masked (mGal)
*Projected coordinates (x and y) are in Weddell Lambert with two standard parallels defined as follows:
Latitude of false origin: -80
Longitude of false origin: -81
Latitude of 1st standard parallel -82
Latitude of 2nd standard parallel -78
False easting 26501
False northing 1977093
|Data Set Creator||Olesen, A., Ferraccioli, F., Forsberg, R., Jordan, T., Matsuoka, K., Zakrajsek, A., & Ghidella, M.|
|Data Set Title||Processed line aerogravity data over the Recovery Lakes region and interior Dronning Maud Land, East Antarctica (2013)|
|Data Set Publisher||UK Polar Data Centre, Natural Environment Research Council, UK Research & Innova|
|Other Citation Details||shortdoi:10/dpqb|
|Horizontal Resolution Range||30 meters - < 100 meters|
|Vertical Resolution Range||N/A|
|Temporal Resolution Range||N/A|
|Detailed Location||the Recovery Lakes region and interior Dronning Maud Land, East Antarctica|
|Distribution Media||Online Internet (HTTP)|
|Distribution Size||306 MB|
|Data Storage:||This dataset constains 1 ASCII XYZ file:
- ICEGRAV_Grav_ByFlight.XYZ ~306MB
|Use Constraints:||This data is covered by a UK Open Government Licence (http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/) Further by downloading this data the user acknowledges that they agree with the NERC data policy (http://www.nerc.ac.uk/research/sites/data/policy.asp), and the following conditions:
1. To cite the data in any publication as follows:
Olesen, A., Ferraccioli, F., Forsberg, R., Jordan, T., Matsuoka, K., Zakrajsek, A., & Ghidella, M. (2020). Processed line aerogravity data over the Recovery Lakes region and interior Dronning Maud Land, East Antarctica (2013) [Data set]. UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation. https://doi.org/10.5285/28E3B21F-BF4B-46A6-8559-F69D69C63A48
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.