HR: 10:20h
AN: GP21D-01    [PDF]
TI: Toward the World Digital Magnetic Anomaly Map (WDMAM)
AU: * Ravat, D
EM: ravat@geo.siu.edu
AF: Southern Illinois University Carbondale, Dept of Geology 4324, Carbondale, IL 62901-4324 United States
AU: Ghidella, M
EM: mghidella@dna.gov.ar
AF: Instituto Antartico Argentino, Cerrito 1248, Buenos Aires, 1010 Argentina
AU: Korhonen, J
EM: juha.korhonen@gsf.fi
AF: Geological Survey of Finland, Geological Survey of Finland P.O.Box 96, Espoo, FIN-02151 Finland
AU: Maus, S
EM: smaus@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Abt. 2.3, Room F427 Telegrafenberg, Potsdam, 14473 Germany
AU: McLean, S
EM: Susan.Mclean@noaa.gov
AF: National Geophysical Data Center, E/GC 325 Broadway, Boulder, CO 80305-3328 United States
AU: Reeves, C
EM: reeves@itc.nl
AF: ITC, Hengelosestraat 99, Enschede, 7500 Netherlands
AB: During the 2003 IUGG meeting in Sapporo, Japan, the IAGA working group on Geomagnetic Modeling rekindled the World Digital Magnetic Anomaly Map (WDMAM) project. Even though preparation of such a map may appear a daunting task, the bulk of it could be accomplished within a few years, taking advantage of many existing national to continent-scale and oceanic magnetic anomaly compilations. In addition, Project Magnet high altitude aeromagnetic surveys could be utilized where available and necessary to fill gaps. Similarly, the CHAMP satellite-derived magnetic anomaly field could be downward continued to provide wavelengths greater than 500 km in this magnetic anomaly map. There are a large number of data handling and processing issues that need to be addressed during the preparation of this map and we discuss some of them here: What should the data spacing be? Should the spacing be uneven according to the data availability? At what elevation should the fields be displayed? How to treat the areas of complete lack of near-surface (marine and airborne) magnetic field coverage? How should one treat the long-wavelength anomaly limitations of the near-surface data? What should be the main field model? What should be the techniques for data processing? What should be the techniques for data merging? The ultimate utility of this first generation map is manifold: ranging from geologic interpretation of features of a few km width to recognizing individual geologic provinces in continental assemblages, developing regional models of the bottom of the magnetic layer and/or the Curie isotherm, and plate tectonic reconstructions using magnetic anomalies. The global view and the ability to move the inferred source magnetizations along with the continents and oceanic areas back in time will also significantly aid in deciphering the origin and evolution of geologic provinces presently appearing unrelated due to their vast intervening distances. We recognize the WDMAM as the legacy of the geomagnetists from all around the world and we invite them all to participate enthusiastically in its preparation. A preliminary world map is slated for the IAGA meeting in Toulouse (2005), leading to a first edition release at the IUGG assembly in Perugia (2007) as a contribution to IGY+50. We envisage that the map and dataset will take its place alongside, for example, global topography and seismicity maps and be used and improved by future generations of earth scientists for education, research and the wider societal benefit.
DE: 0900 EXPLORATION GEOPHYSICS
DE: 1517 Magnetic anomaly modeling
DE: 1545 Spatial variations (all harmonics and anomalies)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting