Consistency and Complementarity among Gravity, Deformation, and Ocean Model in the Global Inverse Framework

Wu, Xiaoping; Collilieux, Xavier; Altamini, Zuheir; Vermeersen, Bert L. A.; Gross, Richard S.
Jet Propulsion Laboratory, CALTECH; Xiaoping.Wu@jpl.nasa.gov

Gravity, deformation, geocenter motion, bottom pressure and Earth rotation are different manifestations of present-day and historical surface mass transport, tectonic and other geophysical processes. Observed by multiple satellite geodetic techniques, they can be used to cross-validate in cases of overlapping information, and to complement for global coverage, high resolution and accuracy. We identify the underlying geophysical processes and examine information contents of these data types in a global inverse framework for redundancies and deficiencies. For seasonal and interannual time scales, the multiple data sets provide complete global spatial and spectral coverage on surface mass variations and offer many facets of redundancies. We will compare various direct and inverse observations of geocenter motions, low-degree spherical harmonic coefficients of surface mass variations. For secular trends, we will compare polar wander observations with degree-2 and order-1 gravity trends. However, errors and lack of quantitative uncertainty assessment of glacial isostatic adjustment (GIA) models cloud the evaluation of consistencies among the data sets. To separate present-day surface water transport trend from GIA, barely enough data exist and a priori information has to be used carefully. Tremendous progress has been achieved since GRACE was launched in 2002. Still, inconsistencies exist among different data types, which need further improvement.