DOI: 10.5285/c8d67254-7a66-4ec4-9df8-9dc1c254add5
title: Processed line aeromagnetic data over the Dufek Massif, Pensacola Mountains (1998/99 season)

description: A British Antarctic Survey Twin Otter and survey team acquired 8,300 line-km of magnetic data during the Austral summer of 1998/99. Gravity and radio-echo data were acquired simultaneously with the magnetic data at a compromise constant barometric height of 2,200 m, which provides a terrain clearance of 100 m over the highest peaks. Two separate surveys were conducted; one at 5 km line spacing (tie lines at 20 km) over and stretching beyond the southern extent of the Forrestal range (main survey), and one at 2 km line spacing (tie lines at 8 km) covering the Dufek Massif (detailed survey). Wing-tip-mounted cesium vapour magnetometers acquired data at 10 Hz, which was resampled to 1 Hz after deletion of data corrupted by the radio echo transmissions. It is not possible to compensate the magnetic data for maneuver noise after this process as the data are under-;sampled with respect to maneuver noise. However, because gravity data was being acquired at the same time, turbulent conditions were avoided and so maneuver noise was at a minimum. Ashtech Z12 dual frequency GPS receivers were used for survey navigation. Pseudorange data were supplied to a Picodas PNAV navigation interface computer, which was used to guide the pilot along the pre-planned survey lines. The actual flight path was recovered, using carrier-phase, continuous, kinematic GPS processing techniques. All magnetic and pseudorange navigation data were recorded at 1 Hz on a Picodas PDAS 1000, PC-based data acquisition system. Data were de-spiked and then smoothed (~100 m low pass filter), before re-sampling from 10 to 1 Hz. The data were IGRF corrected, leveled and reduced to the pole in the field. A 2.5 km cell grid was produced. The negative bias to the anomaly amplitudes is a result of the poorly defined IGRF in this area. We present here the processed line aeromagnetic data acquired using scintrex cesium magnetometers mounted on the BAS aerogeophysical equiped Twin Otter. Data are provided as XYZ ASCII line data.
description: DUFEK aeromagnetic dataset available here includes fully processed and levelled products. Details of data acquisition and processing steps are presented in Ferris et al., (1998, 2003). Channel description: Basic Channels x x projected meters* y y projected meters * Lon Longitude WGS 1984, Lat Latitude WGS 1984, Mag processing channels MagF Final magnetic data value before levelling (nT) MagL Statistically levelled magnetic data. Tie lines levelled to normal lines initially. (nT) *Projected coordinates (x and y) are in Lambert conic conformal with two standard parallels defined as follows: Latitude of false origin: -80 Longitude of false origin: 80 Latitude of 1st standard parallel -83 Latitude of 2nd standard parallel -77 False easting 2000000 False northing 2000000 Positioning for the Dufek survey uses Ashtech Z12 dual frequency GPS recievers (Ferris et al, 2003). Positions are calculated for the phase centre of the aircraft antenna. All positions (Lat, lon and height) are referred to the WGS1984 ellipsoid.