Mantle viscosity inferences from joint inversions of Pleistocene deglaciation-induced changes in geopotential with a new SLR analysis and polar wander

Joint inversions of post-glacial rebound-induced secular changes in low deg ree harmonics of the geopotential and true polar wander (TPW) systematicall y indicate that the upper mantle viscosity has a value that is considerably smaller than 10(21) Pas. The lower mantle viscosity is about one order of magnitude larger than the upper mantle viscosity. Discrepancies in the visc osity profiles inferred from even and odd zonals are likely an indication o f recent, unmodeled glacial forcings and/or insufficient precision in the e valuation of the mass loss from Pleistocene ice sheets. The influence of sy stematic errors in SLR data reduction due. to thermal drag on the LAGEOS sa tellites for the uneven zonals of the geopotential is avoided by making use of the Starlette and Stella satellites to recover the uneven zonals and by considering lumped coefficients for these uneven terms.