Abstract:
This data set contains aerogravity data collected during the WISE/ISODYN project. This collaborative UK/Italian project collected ~ 61000 line km of new aerogeophysical data during the 2005/2006 austral summer, over the previously poorly surveyed Wilkes subglacial basin, Dome C, George V Land and Northern Victoria Land.
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.
Keywords:
Aerogeophysics, Aerogravity, Antarctica
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
| 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: 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. |
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| Creation Date: | 2020-07-01 |
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| Dataset Progress: | Planned |
| Dataset Language: | English |
| ISO Topic Categories: |
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| Parameters: |
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| Personnel: | |
| Name | PDC BAS |
| Role(s) | Metadata Author |
| Organisation | British Antarctic Survey |
| Name | Dr Tom A Jordan |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Dr Fausto Ferraccioli |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | E. Armadillo |
| Role(s) | Investigator |
| Organisation | DISTAV, University di Genova, Genoa, Italy |
| Name | E. Bozzo |
| Role(s) | Investigator |
| Organisation | DISTAV, Universita di Genova, Genoa, Italy |
| Parent Dataset: | N/A |
| Reference: | Main reference: Ferraccioli, F., Armadillo, A., Jordan, T.A., Bozzo, E. & Corr, H., 2009. Aeromagnetic exploration over the East Antarctic Ice Sheet: a new view of the Wilkes Subglacial Basin, Tectonophysics, 478, 62-77, doi:10.1016/j.tecto.2009.1003.1013. Processing references: Ferraccioli, F., Gambetta, M. & Bozzo, E., 1998. Microlevelling procedures applied to regional aeromagnetic data: an example from the Transantarctic Mountains (Antarctica), Geophysical Prospecting, 46, 177-196, https://doi.org/10.1046/j.1365-2478.1998.00080.x Ferraccioli, F., Jordan, T.A., Armadillo, A., Bozzo, E., Corr, H., Caneva, G., Robinson, C., Frearson, N. & Tabacco, I.E., 2007. Collaborative aerogeophysical campaign targets the Wilkes Subglacial Basin, the Transantarctic Mountains and the Dome C region. in The Italian-British Antarctic Geophysical and Geological Survey in Northern Victoria Land 2005-06-Towards the International Polar Year 2007-08., pp. 1-36, eds. Bozzo, E. & Ferraccioli, F. Terra Antartica Reports. Pilkington, M. & Thurston, B.J., 2001. Draping corrections for aeromagnetic data: line versus grid-based approaches, Exploration Geophysics, 32, 95-101.https://doi.org/10.1071/EG01095 Fremand, A. C., Bodart, J. A., Jordan, T. A., Ferraccioli, F., Robinson, C., Corr, H. F. J., Peat, H. J., Bingham, R. G., and Vaughan, D. G.: British Antarctic Survey's aerogeophysical data: releasing 25 years of airborne gravity, magnetic, and radar datasets over Antarctica, Earth Syst. Sci. Data, 14, 3379-3410, https://doi.org/10.5194/essd-14-3379-2022, 2022. |
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| Lineage: | 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 Lambert conic conformal with two standard parallels defined as follows: Latitude of false origin: -74.018118 Longitude of false origin: 179 Latitude of 1st standard parallel -72.66666666667 Latitude of 2nd standard parallel -75.33333333333 False easting 1444000 False northing 1123000 |
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| Temporal Coverage: | |
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| Start Date | 2005-12-04 |
| End Date | 2006-01-25 |
| Spatial Coverage: | |
| Latitude | |
| Southernmost | -74.39164 |
| Northernmost | -68.97639 |
| Longitude | |
| Westernmost | 138.76981 |
| Easternmost | 171.77913 |
| Altitude | |
| Min Altitude | N/A |
| Max Altitude | N/A |
| Depth | |
| Min Depth | N/A |
| Max Depth | N/A |
| Data Resolution: | |
| Latitude Resolution | N/A |
| Longitude Resolution | N/A |
| Horizontal Resolution Range | 30 meters - < 100 meters |
| Vertical Resolution | N/A |
| Vertical Resolution Range | N/A |
| Temporal Resolution | N/A |
| Temporal Resolution Range | N/A |
| Location: | |
| Location | Antarctica |
| Detailed Location | Wilkes Subglacial Basin |
| Sensor(s): |
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| Source(s): |
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| Distribution: | |
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| Distribution Media | Online Internet (HTTP) |
| Distribution Size | 340 MB |
| Distribution Format | ASCII |
| Fees | N/A |
| Data Storage: | This dataset constains 2 ASCII XYZ files: -WISE_ISODYN_GravByFlight.XYZ ~220MB - WISE_ISODYN_Auxilary_gravity_lines.XYZ ~128MB |