Dynamic Topography as Reflected in the Global Gravity Field
The long-wavelength part of non-isostatic topography is supposed to be generated by mantle dynamics and is up to now not well studied. In order to separate the dynamic part from the residual topography (that part of the Earth's topography which is not explained by the crustal model providing isostatic compensation) a correlation analysis is performed between the residual topography and long-wavelength isostatic gravity anomalies. It is found that the correlation between these quantities is positive for spatial wavelengths larger than 4000 km. The resulting correlated part of residual topography is regarded to represent the dynamic topography. Its amplitude was estimated to range from −0.4 to 0.5 km and is on the lower limit of what was estimated from a direct modelling of mantle convection. The calculated dynamic topography may be used as a strong constraint in further numerical simulations of mantle dynamics.
Key wordsdynamic topography isostatic gravity anomalies global gravity field model
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