Glacial isostatic adjustment on a rotating earth
Abstract
We extend and complete previous work to compute the influence of perturbations to the rotation vector on a suite of observables associated with glacial isostatic adjustment (GIA). We emphasize observables relevant to present and future geodetic missions (for example, presentday 3D crustal motions, relative sealevel change and geoid or absolute sealevel variations). Our calculations adopt spherically symmetric, selfgravitating, Maxwell viscoelastic earth models while incorporating realistic mass (ice plus ocean) load and rotation variations. The predicted rotationinduced signals are dominated by the influence of true polar wander (TPW). The spatial geometry of the TPWinduced relative sea level, geoid and radial velocity fields is primarily that of a degree two, order one surface spherical harmonic. The spatial variation of the horizontal velocity vectors is given by the gradient of this harmonic. The peak radial and horizontal velocities are of the order of 0.5mmyr^{1} ; however, we show that this value is sensitive to the adopted profile of mantle viscosity. We also demonstrate that an accurate prediction of TPWinduced sea level and 3D crustal deformation rates requires that a realistic number of glacial cycles be incorporated into the ice load history. We conclude that geodetic observations of the GIA process should be analysed using a GIA theory valid for a rotating planet. Finally, we also consider variations in rotation driven by simple presentday polar melting scenarios and predict the influence of these variations on a suite of geophysical observables. We find that the rotational feedback associated with Greenland melting is capable of significantly perturbing both relative and absolute sealevel variations.
 Publication:

Geophysical Journal International
 Pub Date:
 December 2001
 DOI:
 10.1046/j.0956540X.2001.01550.x
 Bibcode:
 2001GeoJI.147..562M
 Keywords:

 3D CRUSTAL DEFORMATIONS;
 EARTH'S ROTATION;
 GEODESY;
 GLACIAL REBOUND;
 SEA LEVEL