HR: 08:15h
AN: GP41A-02    [Abstracts]
TI: A new selection of archeomagnetic data for high resolution geomagnetic field modeling
AU: * Donadini, F
EM: fdonadini@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093, United States
AU: Korte, M
EM: monika@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Constable, C
EM: cconstable@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093, United States
AB: To understand the content and the causes of the changes in the Earth's magnetic field beyond the observatory record one has to rely on archeomagnetic and lake sediment paleomagnetic data. Regional archeomagnetic intensity and direction curves are often of variable quality and completeness, hampering the ability to uncover non-dipole field contributions in global data analysis and modeling. Poor age control in many records further limits the temporal resolution attainable. Millennial scale models like CALS7K.2 are built using all the available data, but an alternative strategy is to use specific selection criteria and (inevitably) smaller numbers data in an attempt to produce higher resolution models.
High resolution variation of the geomagnetic field during the last 3000 years is investigated using selected archeointensity and directional data, drawn from the current GEOMAGIA50 database, and a collection of directional data initially based on the CALS7K compilation but now updated to include some missing data and recently published results. The maximum standard age error for each datum was set to 100 years, the maximum standard VADM error to 2 VADM units, and the maximum α₉₅ confidence cone to 5 degrees.
The constrained dataset is used to create new high resolution global geomagnetic field models for the past 3000 years. The modeling strategy is generally similar to that used for CALS7K. Minor modifications to the algorithm allow us to use the GUFM historical field model as an additional constraint and recover a higher resolution field model fro 1600AD to the present. This addresses a weakness of the CALS7K model which suffers from diminishing numbers of paleomagnetic records for the most recent times, and is unreliable near both the beginning and end of the time interval spanned. We will present results illustrating the effects of our data selection and modeling efforts for the 0-3~ka geomagnetic field.
DE: 1503 Archeomagnetism
DE: 1522 Paleomagnetic secular variation
DE: 1560 Time variations: secular and longer
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting