2017/10/17 by Julien Baerenzung, Baerenzung, Julien, M. Holschneider +8 · 3 citations
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · Economics, Econometrics and Finance · #86-08 #Complex Systems and Time Series Analysis #Earthquake Detection and Analysis #FOS: Physical sciences #Geomagnetism and Paleomagnetism Studies #Geophysical and Geoelectrical Methods #Geophysics (physics.geo-ph) #Geophysics and Gravity Measurements
paper · pdf · doi:10.48550/arxiv.1710.06188
openalex publication_date 2017/10/17 · openalex created_date 2022/10/02 · openalex updated_date 2026/07/28
The coupled evolution of the magnetic field and the flow at the Earth's core\nmantle boundary is modeled within the 1900.0-2014.0 time period. To constraint\nthe dynamical behavior of the system with a core field model deriving from\ndirect measurements of the Earth's magnetic field we used an Ensemble Kalman\nfilter algorithm. By simulating an ensemble of possible states, access to the\ncomplete statistical properties of the considered fields is available.\nFurthermore, the method enables to provide predictions and to assess their\nreliability. In this study, we could highlight the cohabitation of two distinct\nflow regimes. One associated with the large scale part of the eccentric gyre,\nwhich evolves slowly in time and posses a very long memory of its past, and a\nfaster one associated with the small scale velocity field. We show that the\nlatter can exhibit rapid variations in localized areas. The combination of the\ntwo regimes can predict quite well the decadal variations in length of day, but\nit can also explain the discrepancies between the physically predicted and the\nobserved trend in these variations. Hindcast tests demonstrate that the model\nis well balanced and that it can provide accurate short term predictions of a\nmean state and its associated uncertainties. However, magnetic field\npredictions are limited by the high randomization rate of the different\nvelocity field scales, and after approximately 2000 years of forecast, no\nreliable information on the core field can be recovered.\n