HR: 16:30h
AN: GP24A-04    [Abstracts]
TI: New Model Alternatives for Improving the Representation of the Core Magnetic Field of Antarctica
AU: * Gaya-Pique, L R
EM: pique@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia - Roma 2, Via di Vigna Murata 605, Rome, 00143 Italy
AU: Ravat, D
EM: ravat@geo.siu.edu
AF: Department of Geology 4324, Southern Illinois University Carbondale, Carbondale, IL 62901-4324 United States
AU: De Santis, A
EM: desantisag@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia - Roma 2, Via di Vigna Murata 605, Rome, 00143 Italy
AU: Torta, J
EM: jmtorta@obsebre.es
AF: Observatori de l'Ebre, Horta Alta 38, Roquetes, 43520 Spain
AB: The use of the International Geomagnetic Reference Field Model (IGRF) in constructing magnetic anomaly maps can lead to problems in the determination of magnetic anomalies. The major problems occur at the edges of local or regional magnetic surveys carried out in different epochs, which appear due to inaccuracies in the continuation of long wavelength anomalies. The interpretation of the resulting anomaly maps can therefore be erroneous. The situation is much worse in polar regions like Antarctica where magnetic activity of external origin is intense and only a few ground magnetic observatories exist; thus, it is even more difficult to separate ionospheric variations properly from the secular variation of the core magnetic field. In this paper, we examine two alternatives to the piecewise-continuous IGRF core magnetic field in Antarctica for the last 45 years: the present global Comprehensive Model (CM4) and the new version of the Antarctic Reference Model (ARM). It will be shown through different examples that both these continuous models represent the secular variation in Antarctica more adequately than IGRF: for instance, the improvement of ARM relative to IGRF-9 model is higher than 30% for the secular change of the total intensity field since 1960 for the overall Antarctic observatory compilation. Other examples concerning ground, shipborne, and aeromagnetic measurements will be presented. We therefore recommend the use of either the CM4 or the regional ARM model as possible candidates for defining the crustal magnetic field of Antarctica (e.g., the next generation of the Antarctic Digital Magnetic Anomaly Map).
DE: 1532 Reference fields (regional, global)
DE: 1545 Spatial variations (all harmonics and anomalies)
DE: 1560 Time variations--secular and long term
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2005 Joint Assembly