PADM2M: A Time-varying Model of Paleomagnetic Axial Dipole Moment for 0- 2Ma

Earth's dynamic history can be investigated by looking at the mark left in the paleomagnetic record. Core processes drive the continuously changing geomagnetic field, which has been recorded on Earth's surface by newly forming igneous rocks and sediments. We construct a continuous time varying model of Paleomagnetic Axial Dipole Moment (PADM) variations over the past two million years using almost 1500 globally distributed absolute paleointensity data from the PINT08 and Geomagia50 databases and 90 distinct relative paleointensity records from sediment cores that are now archived in the MagIC PMAG database. Our modeling is carried out using maximum likelihood (ML) estimation to find a regularized cubic B-spline model with reasonable misfit to the data. As part of the modeling procedure we solve for scaling factors needed to transform the relative paleointensity records to virtual axial dipole moments (VADM). The resulting model is designated PADM2M and provides a new global estimate of the time varying PADM for 0-- 2~Ma. We compare our results to existing relative paleointensity stacks and find both similarities and differences. Similarities include the recovery of the expected paleointensity lows at field reversals and excursions, while differences are best illustrated by a statistical analysis of the properties of the model.