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., & Robinson, C. (2021). Processed line aeromagnetic data over the Thwaites glacier region (2019/2020 season) (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/EB6BF8DF-EA87-4C3C-8F27-33FA8D5AC663

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.

Methodology:

Raw line aeromagnetic data from the December 2019 ITGC airborne survey were initially corrected for the regional geomagnetic field (IGRF), and compensated for aircraft motion. Compensation coefficients were calculated from a calibration flight flown ~500m above the Lower Thwaites Glacier field camp during the previous season, and are therefore not optimal. The dataset may benefit from a low pass filter to remove residual noise due to aircraft dynamic motion. Diurnal variations in the magnetic field were recorded at 30 second intervals using a base station at Lower Thwaites Glacier field camp. Base station corrections were calculated by subtracting the local mean base station value across the survey from the recorded base station values. The base station corrections were then filtered with a 30 minute filter to ensure short wavelength signals, likely only seen at the base station, were not transferred to the airborne dataset. No base correction was applied to any of the transits, or initial calibration flights. An additional Tip Tank correction was made to remove the offsets induced by aircraft operational procedures such as pumping fuel. This correction is generally restricted to turns and transits, as data quality is worse during these times, and users may wish to consider discarding this data.

DATA FORMAT:

Data are provided in ASCII file format (.csv).

The data set includes the following channels:

FlightID: Sequential survey flight number from T1 to T17.

x: coordinate (m) Polar stereographic true scale -71

y: coordinate (m) Polar stereographic true scale -71

Lon: Longitude DDD.DDDDDDDD

Lat: Latitude DD.DDDDDDDD

Height_WGS1984: Elevation on the WGS1984 ellipsoid (m)

Date: Date YYYY/MM/DD

Time: Time (GPS) HH:MM:SS.SSSSS

MagR: Raw total field magnetic data (nT)

MagC: Compensated total field magnetic data (nT)

RefField: IGRF correction (nT)

TCorr:Tip correction (nT)

MagRTC: Mag after IGRF, compensation and tip correction (nT)

Bcorr: Base station correction with 30 minute mean filter (nT)

MagBRTC: Mag after all corrections (nT)

Data collection:

Data was collected using the BAS aerogeophysically 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 proton procession magnitomiters set up as base stations and recording 1 sample every 30 seconds was used during data processing.

Data quality:

After the basic processing presented here the standard deviation of the crossover errors within the ITGC survey was 14.83 nT.

The line spacing for the survey is variable between 5 km and 10 km. Line data is generally designed to interleave with existing AGASEA data. The provided data is sampled at 10Hz, which equates to a 6m along track sample spacing. A ~1Hz sinusoidal signal is recognised in the data, and application of 3 second (18 m) low pass filter is therefore recommended. The true usable resolution of this dataset is proportional to the depth to source, which is typically 750 to 1500 m.