DOI: 10.5285/33b9cdf7-3fc6-41ec-8b53-650410dd0a4d
title: High resolution processed line aeromagnetic data over James Ross Island, Northern Antarctic Peninsula (1997/1998)

description: Gravity, magnetic and radar data were acquired during a joint UK-Argentina (BAS/IAA) project, during the austral summer 1998-1999. 10,771 line km of data were acquired using a BAS Twin Otter, covering an area of 21,000 km2 that comprises the James Ross Island archipelago and the NW corner of the Weddell Sea. Gravity and magnetic data were simultaneously acquired at a constant barometric height of 2000 m, providing a terrain clearance of approximately 100 m over the highest peaks. The main flight lines were flown along an E-W direction with 2000 m spacing over James Ross Island and at 4000 m interval offshore. Tie lines, oriented meridionally, were spaced 10,000 m and extended beyond the magnetic survey to provide a regional context to the survey area as required also for airborne gravity data analysis. Magnetic data were acquired at a frequency of 10 Hz using vapour cesium magnetometers mounted on the aircraft wing tips, and resampled to 1 Hz after compensation for manoeuvre noise. A triaxial fluxgate magnetometer was mounted close to the tail of the aircraft, providing magnetic attitude information used in the data compensation. However, gravity acquisition defines that turbulent conditions are avoided and so manoeuvre noise is generally minimal. Ashtech Z12 duel frequency GPS receivers were used for survey navigation and for post-processing of the GPS data. Magnetic data were de-spiked to remove avionics noise and then smoothed (- 300 m low pass filter), before re-sampling from 10 to 1 Hz. The data were first corrected for diurnal variations using low-pass filtered base station data (30 min low-pass filter). For the internal field we used the Definitive Geomagnetic Reference Field Model 1995. The final data processing step was network levelling and microlevelling (Ferraccioli et al., 1998). We present here the processed line aeromagnetic data collected using scintrex cesium magnetometers mounted on the BAS aerogeophysical equipped Twin Otter. Data are provided as XYZ ASCII line data.
description: JRI aeromagnetic dataset available here includes final levelled products. Channel naming follows SCAR/ADMAP2 data release protocols. Magnetic data channels and processing flow: Note that raw magnetic data and processing steps are currently not available for download. MagF- Final mag value before levelling. MagL- Statistically levelled mag data. Basic channel description: x x projected meters * y y projected meters * Lon Longitude WGS 1984, Lat Latitude WGS 1984, *Projected coordinates (x and y) are in Polar sterographic 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 Positioning for the JRI survey used an Ashtech Z12 dual frequency receiver in the aircraft and at a fixed base station (Jordan et al., 2009). Differential, carrier phase, kinematic GPS methods were then used to calculate all the navigational information used. Positions are calculated for the phase centre of the aircraft antenna. All positions (Lat, lon and height) are referred to the WGS1984 ellipsoid. Database channels are described in the table below.
description: Only MagL is provided in the file. Other channels are included for compatibility with ADMAP2 convention, but are not filled as were not available.