Using empirical mode decomposition to process marine MT data.

Chen, Jin, Heincke, Björn, Jegen, Marion and Moorkamp, Max (2012) Using empirical mode decomposition to process marine MT data. Open Access Geophysical Journal International, 190 . pp. 293-309. DOI 10.1111/j.1365-246X.2012.05470.x.

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Abstract

Magnetotellurics (MT) uses a frequency-dependent impedance tensor estimated from the spectra of associated time-varying horizontal electric and magnetic fields measured at the Earth's surface to image the sub-surface of the Earth. Most current methods use Fourier transform based procedures to estimate power spectral densities and, therefore, assume that the signals are stationary over the record length. Stationarity in geomagnetic data, however,
is not always ensured given the variety of source mechanism
causing the geomagnetic variations at different time and spatial scales. Additional complication and bias may arise from the presence of noise in the recorded electric and magnetic file data.
Sophisticated MT data processing account for a potential bias through windowing of the time series as well as robust estimates of the impedance. We explore a new heuristic method for dealing with the non-stationarity of MT time series based on empirical mode decomposition. It is a dynamic time series analysis method, in which complicated data sets can be decomposed into a finite and small number of simple intrinsic mode functions. In this paper, we use the empirical mode decomposition method to decompose MT data
into intrinsic mode functions and calculate the instantaneous frequencies and spectra to determine the impedance tensor. We investigate the reliability of the impedance estimates on synthetic data by comparing the results to those obtained by analytical methods. Finally, we apply our processing scheme to data measured from the Costa Rica subduction zone, and compare the results from our new method to the frequently-used BIRRP processing method.

Document Type: Article
Additional Information: This article has been published in Geophysical Journal International ©2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Keywords: Geodynamics; Magnetotelluric; time series analysis; empirical mode decomposition ;
Research affiliation: OceanRep > SFB 574
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
OceanRep > SFB 574 > N01
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1111/j.1365-246X.2012.05470.x
ISSN: 0956-540X
Projects: Future Ocean, SFB574
Contribution Number:
ProjectNumber
SFB 574243
Date Deposited: 11 Jan 2012 13:32
Last Modified: 10 Jul 2018 09:38
URI: http://oceanrep.geomar.de/id/eprint/13395

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