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:

Ferraccioli, F., Jones, P., & Smith, A. (2020). Processed line aeromagnetic data over Ellsworth Land (2001) [Data set]. UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation. https://doi.org/10.5285/2E0EBBC5-1539-4F3C-873D-C62EA354C35C

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:

TORUS aeromagnetic dataset available here includes all channels from raw through to levelled, and draped products. Channel naming follows SCAR/ADMAP2 data release protocols.

Also included in the available database are base level survey lines flown previously which complement the main TORUS grid. These lines have been processed in accordance with SCAR/ADMAP2 protocols but have not been levelled with TORUS data.

Magnetic data channels and processing flow:

Note that TORUS processing work flow is ordered differently to ADMAP2 protocols, but naming conventions, compensations and corrections are adhered to.

MagR- Raw magnetic total field intensity data (nT).

MagC- Compensated, or low pass filtered magnetic data. Adjustments to compensate for aircraft roll, pitch and yaw were applied.

TCorr- Tiptank corrections (nT). These include DC shifts and gradients due to aircraft noice, etc. Dummy values if not applicable.

MagTC- Compensated magnetic value adjusted for Tip tanks (where used). MagTC= MagC- TCorr (nT).

BCorr- Low pass filtered (60 minute) magnetic base station correction.

MagBTC- Compensated, tip tank and base station corrected mag. MagBTC= MagTC-BCorr (nT)

RefField- Geomagnetic reference field value for which the magnetic data has been compensated. IGRF model 2010 as implemented in Geosoft (nT).

MagBRTC- calculated as MagBRTC= MagBTC- RefField (nT).

SCorr- Low pass filter (25 fiducials) applied to extra lines merged into the database with remnant noise.

MagF- Final mag value before levelling (nT).

MagL- Statistically levelled mag data (nT).

MagML- Microlevelled magnetic data following technique of (Ferraccioli et al., 1998). Note tie lines are not included in the microlevelled data channel (nT).

Basic channel description:

Line name Line Number

Flight ID Sequential flight number

x x projected meters*

y y projected meters*

Lon Longitude WGS 1984,

Lat Latitude WGS 1984,

Height_WGS1984 Aircraft altitude (meters) in WGS 1984,

Date Date of flight in time format e.g. 2006/01/08

Time Time (UTC) of flight e.g. 23:52:42.0

*Projected coordinates (x and y) are in Lambert conic conformal with two standard parallels defined as follows:

Latitude of natural origin: -71

Longitude of natural origin: 0

Scale factor at natural origin 0.994

False easting 0

False northing 2082760.109