HR: 08:00h
AN: GP51A-01 INVITED     [Abstracts]
TI: Possibilities for Extending Time-Varying Geomagnetic Field Models to 100~ka
AU: * Constable, C
EM: cconstable@ucsd.edu
AF: IGPP, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093-0225, United States
AB: Knowledge of millennial scale variations in the past geomagnetic field has been greatly enhanced over the past decade by extensive data gathering efforts combined with a systematic development of global time-varying spherical harmonic models like CALS7K.2 which covers the past 7 thousand years. I explore prospects for extending such modeling to 100~ka, using marine sediment and lava flow records of the paleosecular variation. Such modeling must take account of a variety of limitations in the paleomagnetic data available, including restricted geographic and temporal coverage. Only secular variation on the largest spatial scales can be recovered. Another major consideration is evaluating the uncertainty in age associated with individual observations of either direction or field strength, and treating such uncertainties in an appropriate way during the modeling process. These age uncertainties directly limit the temporal resolution attainable in global field modeling. Relative paleointensity records derived from sediments require calibration during the modeling process, and all paleomagnetic data require a careful assessment of their accuracy so that the best quality model can be produced. Current modeling strategies based on temporally and spatially regularized inversion will be evaluated and simple modifications proposed to accommodate the limited information content in paleomagnetic data.
DE: 1522 Paleomagnetic secular variation
DE: 1532 Reference fields: regional, global
DE: 1545 Spatial variations: all harmonics and anomalies
DE: 1560 Time variations: secular and longer
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly