Statistically Assessing Time-Averaged and Paleosecular Variation Field Models Against Paleomagnetic Directional Data Sets. Can Likely non-Zonal Features be Detected in a Robust way ?

HR: 14:30h
AN: GP23A-04 INVITED [Abstracts]
TI: Statistically Assessing Time-Averaged and Paleosecular Variation Field Models Against Paleomagnetic Directional Data Sets. Can Likely non-Zonal Features be Detected in a Robust way ?
AU: * Hulot, G
EM: gh@ipgp.jussieu.fr
AF: Equipe de Géomagnétisme, IPGP, 4, Place Jussieu, B89, Tour 14-15, 2nd, cedex 05, Paris, 75252, France
AU: Khokhlov, A
EM: fbmotion@yandex.ru
AF: Equipe de Géomagnétisme, IPGP, 4, Place Jussieu, B89, Tour 14-15, 2nd, cedex 05, Paris, 75252, France
AU: Khokhlov, A
EM: fbmotion@yandex.ru
AF: International Institute of Earthquake Prediction Theory and Mathematical Geophysics, 79, b2, Warshavskoe shosse, Moscow, 117556, Russian Federation
AB: We recently introduced a method to rigorously test the statistical compatibility of combined time-averaged (TAF) and paleosecular variation (PSV) field models against any lava flow paleomagnetic database (Khokhlov et al., 2001, 2006). Applying this method to test (TAF+PSV) models against synthetic data produced from those shows that the method is very efficient at discriminating models, and very sensitive, provided those data errors are properly taken into account. This prompted us to test a variety of published combined (TAF+PSV) models against a test Bruhnes stable polarity data set extracted from the Quidelleur et al. (1994) data base. Not surprisingly, ignoring data errors leads all models to be rejected. But taking data errors into account leads to the stimulating conclusion that at least one (TAF+PSV) model appears to be compatible with the selected data set, this model being purely axisymmetric. This result shows that in practice also, and with the data bases currently available, the method can discriminate various candidate models and decide which actually best fits a given data set. But it also shows that likely non-zonal signatures of non-homogeneous boundary conditions imposed by the mantle are difficult to identify as statistically robust from paleomagnetic directional data sets. In the present paper, we will discuss the possibility that such signatures could eventually be identified as robust with the help of more recent data sets (such as the one put together under the collaborative "TAFI" effort, see e.g. Johnson et al. abstract #GP21A-0013, AGU Fall Meeting, 2005) or by taking additional information into account (such as the possible coincidence of non-zonal time-averaged field patterns with analogous patterns in the modern field).
DE: 1522 Paleomagnetic secular variation
DE: 1545 Spatial variations: all harmonics and anomalies
DE: 1599 General or miscellaneous
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting