Oceanic Residual Topography Agrees With Mantle Flow Predictions at Long Wavelengths

Ting Yang*, Louis Moresi, R. Dietmar Müller, Michael Gurnis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Dynamic topography, the surface deflection induced by sublithosheric mantle flow, is an important prediction made by geodynamic models, but there is an apparent disparity between geodynamic model predictions and estimates of residual topography (total topography minus lithospheric and crustal contributions). We generate synthetic global topography fields with different power spectral slopes and spatial patterns to investigate how well the long-wavelength (spherical degrees 1 to 3) components can be recovered from a discrete set of samples where residual topography has been recently estimated. An analysis of synthetic topography, along with observed geoid and gravity anomalies, demonstrates the reliability of signal recovery. Appropriate damping factors, which depend on the maximum degree in the spherical harmonic expansion that is used to fit the samples, must be applied to recover the long-wavelength topography correctly; large damping factors smooth the model excessively and suppress residual topography amplitude and power spectra unrealistically. Recovered long-wavelength residual topographies based on recent oceanic point-wise estimates with different spherical expansion degrees agree with each other and with the predicted dynamic topography from mantle flow models. The peak amplitude of the long-wavelength residual topography from oceanic observations is about 1 km, suggesting an important influence of large-scale deep mantle flow.

Original languageEnglish
Pages (from-to)10,896-10,906
JournalGeophysical Research Letters
Volume44
Issue number21
DOIs
Publication statusPublished - 16 Nov 2017
Externally publishedYes

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