Abstract:
The ESA PolarGap airborne gravity, lidar/radar and aeromagnetic survey was carried out in Antarctica in the field season 2015/16.
The purpose of the 2015/16 ESA PolarGAP airborne survey of the South Pole region was to fill the gap in satellite gravity coverage, enabling construction of accurate global geoid models. Additional radar flights over the Recovery Lakes for the Norwegian Polar Institute (NPI) were carried out as part of the same survey. In conjunction with the primary datasets aeromagnetic data was collected opportunistically, to provide new insights into the subglacial geology.
Data were collected using a caesium magnetometer system, and have been corrected to total field values following the approach laid out by the SCAR ADMAP working group (http://admap.kopri.re.kr/ADMAP-2_SCR_27Aug13.pdf).
The aircraft used was the BAS aerogeophysicaly equipped twin otter VP-FBL.
Data are available as an ASCII table (.csv).
Keywords:
Aerogeophysics, Aeromagnetics, Antarctica, Magnetics, South Pole, geophysics
| Access Constraints: | None |
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| 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: https://doi.org/10.5270/esa-8ffoo3e - PolarGap: "Filling the GOCE polar gap in Antarctica and ASIRAS flight around South Pole" 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. |
| Creation Date: | 2021-11-11 |
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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 | Mr Carl Robinson |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Dr Kenichi Matsuoka |
| Role(s) | Investigator |
| Organisation | Norvegian Polar Institute |
| Name | Dr Arne V Olesen |
| Role(s) | Investigator |
| Organisation | Technical University of Denmark |
| Name | Dr Rene Forsberg |
| Role(s) | Investigator |
| Organisation | Technical University of Denmark |
| Name | Dr Fausto Ferraccioli |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Parent Dataset: | N/A |
| Reference: | Processing references: Shenwary, G.S., Kohistany, A.H., Hussain, Sardar, Ashan, Said; Mutty, A.S.; Daud, M.A.; Wussow, M.W., Sweeney, R.E., Phillips, J.D., Lindsay, C.R., Kucks, R.P., Finn, C.A., Drenth, B.A., Anderson, E.D., Abraham, J.D.; Liang, R.T., Jarvis, J.L., Gardner, J.M., Childers, V.A., Ball, D.C., and Brozena, J.M., 2011, Aeromagnetic surveys in Afghanistan-An updated website for distribution of data: U.S. Geological Survey Open-File Report 2011-1055, 8 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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| Quality: | After the basic processing presented here the standard deviation of the crossover errors was 52 nT, after preliminary levelling the crossover error was 25 nT. Data resolution: The radial design of the survey makes defining a specific resolution problematic. Line spacing at the survey edges was 90 km, reducing towards South Pole. The provided data is sampled at 1Hz, along track which equates to a ~60m along track sample spacing. The true usable resolution of this dataset is proportional to the depth to source, which averages to 2900 m across the survey. |
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| Lineage: | The raw aeromagnetic data was initially corrected for DC offsets due to aircraft procedures, such as pumping fuel from so called 'tip tanks'. Most of these corrections were in turns, but logistical considerations meant such corrections on lines were unavoidable. Due to the unusual radial survey design normal compensation for aircraft dynamics was not possible. However, visual comparison between recorded fluxgate and total field data on the aircraft suggested most dynamic noise had a frequency of <15 seconds (~900m). The tip corrected data was therefore filtered with a 15 second low pass filter to remove dynamic noise prior to decimation from 10Hz to 1Hz to enhance the efficiency of data processing. The total field magnetic data was corrected for the core field using the 2015 IGRF, implemented in the Geosoft software package. The base-station correction for diurnal variations was derived from multiple base-station observations. Base station data at the PolarGAP field camps (Thiel Mountains and FD83) was collected using total-field sensors, with additional fluxgate magnetometer data from the Polar Experiment Network for Geospace Upper atmosphere Investigations (PENGUIn) at South Pole and other remote field sites. All base station data was converted into total field values, and each station corrected to have a zero mean across the survey period. The theoretical base station value at the aircraft was calculated using an inverse distance weighting scheme to merge base station observations (Shenwary et al 2011). This incorporates the base station corrections from all available base stations weighted by their distance to the survey aircraft. This technique provided a smooth transition between different base stations, and ensures the most 'local' base station dominates the correction. As short wavelength diurnal variations observed at a base station are often not fully representative of those occurring at large distances from the base station, the base station corrections were filtered with either a 60 or 30 minute low-pass filter. The base station data is also provided for reference. After base station correction preliminary levelling of the 30 minute base station corrected magnetic data was carried out. This included minimising internal crossovers and discrepancies with other surveys in the region. In general the preferred levelling method removed a 0, or 1st order trend revealed by errors at a number of intersections. Where residual line to line discrepancies remained, more complex spline levelling was applied. Further improvement of the dataset by more detailed levelling may be possible. The aeromagnetic data set includes the following channels: Line: Sequential survey flight number from P03 to P39: decimals denote line breaks. Lon: Longitude DDD.DDDDDDDD Lat: Latitude DD.DDDDDDDD Elev: Elevation on the WGS1984 ellipsoid Date: Date YYYY/MM/DD Time: Time (UTC) HH:MM:SS.SS MagR: Raw total field magnetic data (nT) MagC: Pseudo-compensated total field magnetic data (nT) TCorr: Tip correction (nT) RefField: IGRF correction (nT) MagRTC: Mag after IGRF: compensation and tip correction (nT) Bcorr_60min: IDW base station correction with 60 minute mean filter (nT) Bcorr_30min: IDW base station correction with 30 minute mean filter (nT) MagB60RTC: Final mag after 60 min base station correction (nT) MagB30RTC: Final mag after 30 min base station correction (nT) MagL_B30RTC: Magnetic anomaly after preliminary levelling (nT) The magnetic base station data set includes the following channels: Line: PolarGAP flight number TimeUTC: Time UTC (HH:MM:SS.SS) UTCDate: Date (YYYY/MM/DD) Longitude_decimal_degrees: Survey aircraft longitude (DDD.DDDDDDDDD) Latitude_decimal_degrees: Survey aircraft Latitude (DD.DDDDDDDDD) x: Polar stereographic projected aircraft x position (true scale -71) (m) y: Polar stereographic projected aircraft y position (true scale -71) (m) power: Exponential power used in inverse distance weighting. r_TH: Range to Thiel Mountains base station (coordinates -527308.92: 85658.68) r_FD: Range to FD83 base station (coordinates 251981.30: 672276.42) r_PG3: Range to PENGUIn 3 magnetometer (coordinates 344511.27: 446882.90) r_PG4: Range to PENGUIn 4 magnetometer (coordinates 153738.09: 707916.92) r_SP: Range to South Pole Mag_base_Thiels_nT: Thiel Mountains base station: corrected to zero mean (nT). *=no obs Mag_TH_fill_30_nT: Thiel Mountains base station with 30 min filter. Mag_TH_fill_60:_nT Thiel Mountains base station with 60 min filter. Mag_base_FD83_nT: FD83 base station: corrected to zero mean (nT). *=no obs Mag_FD_fill_30_nT: FD83 base station with 30 min filter. Mag_FD_fill_60_nT: FD83 base station with 60 min filter. Mag_base_PG3_nT: Calculated total magnetic field for PENGUIn 3 magnetometer (nT) Mag_PG3_30min_nT: Total magnetic field for PENGUIn 3 magnetometer with 30 min filter. Mag_PG3_60min_nT: Total magnetic field for PENGUIn 3 magnetometer with 60 min filter. Mag_base_PG4_nT: Calculated total magnetic field for PENGUIn 4 magnetometer (nT) Mag_PG4_30min_nT: Total magnetic field for PENGUIn 4 magnetometer with 30 min filter. Mag_PG4_60min_nT: Total magnetic field for PENGUIn 4 magnetometer with 60 min filter. Mag_base_SP_nT: Calculated total magnetic field for South Pole Fluxgate magnetometer (nT) Mag_SP_30min_nT: Total magnetic field for South Pole magnetometer with 30 min filter. Mag_SP_60min_nT: Total magnetic field for South Pole magnetometer with 60 min filter. Mag_base_IDW_30min_nT: 30 min filtered IDW base station correction applied at aircraft (nT) Mag_base_IDW_60min_nT: 60 min filtered IDW base station correction applied at aircraft (nT) |
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| Ownership: | The PolarGAP survey was an ESA funded field campaign, with additional significant in-kind and manpower contributions from project partners BAS, DTU-Space, and the Norwegian Polar Institute (NPI). Logistical support for the survey at South Pole station was provided in collaboration with the US National Science Foundation (NSF). | |
| Temporal Coverage: | |
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| Start Date | 2015-12-15 |
| End Date | 2016-01-20 |
| Spatial Coverage: | |
| Latitude | |
| Southernmost | -90 |
| Northernmost | -80.4 |
| Longitude | |
| Westernmost | -180 |
| Easternmost | 180 |
| Altitude | |
| Min Altitude | N/A |
| Max Altitude | N/A |
| Depth | |
| Min Depth | N/A |
| Max Depth | N/A |
| Location: | |
| Location | Antarctica |
| Detailed Location | South Pole |
| Location | Antarctica |
| Detailed Location | Recovery Lakes |
| Location | Antarctica |
| Detailed Location | Thiel Mountains |
| Sensor(s): |
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| Source(s): |
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| Data Collection: | Data was collected using the BAS aerogeophysicaly equipped twin otter VP-FBL. Magnetic data was collected using wing tip mounted Scintrex CS-3 High Sensitivity Cs magnetometers. Only data from the magnetometer with the lowest noise characteristics is reported here. Data was recorded at 10 Hz on a PicoEnvirotec logging system. Additional base station information from total-field magnitomiters at field camps and fluxgate magnitomiters from the Polar Experiment Network for Geospace Upper atmosphere Investigations (PENGUIn) network were used. |
| Distribution: | |
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| Distribution Media | Online Internet (HTTP) |
| Distribution Size | 255 MB |
| Distribution Format | ASCII |
| Fees | N/A |
| Data Storage: | This dataset contains two CSV datasets: - PolarGAP_mag_ADMAP_ASCII_V2.csv ~79 MB - PolarGAP_mag_Base_V2.csv ~179 MB |