Global Present-Day Surface Water Mass Transport and GIA from Joint Inversions of Multi-Satellite and Interdisciplinary Data

Wu, Xiaoping
Jet Propulsion Laboratory, CALTECH; Xiaoping.Wu@jpl.nasa.gov

GRACE time-variable gravity measurements in the past several years have created the richest information for a single technique with nearly global coverage and high precision about present-day surface water mass transport, glacial isostatic adjustment (GIA), and other geophysical processes. Still, other data and models of these processes have been used to achieve real global coverage, improve precision and sort out contributions of individual processes. However, many geophysical models of these processes are not accurate to modern geodetic precisions. They usually contain no statistical assessment of uncertainties and may have large errors. The largest uncertainty factor in determining present-day surface water transport trend from GRACE gravity measurements is perhaps the contamination from errors of GIA models used to remove GIA from data. Still, the models, especially those constrained by data and with some indications of uncertainties will turn out to be very useful if used properly. Preferably, more data sets with complementary information should be used to resolve the various signatures and to improve the models. In this talk, I will review various data types used in global inversions, their information contents, technical problems and challenges. Their roles and contributions to our understanding and determination of the major geophysical processes will then be discussed, often in the context of global inverse schemes. An example of a recent simultaneous inversion of present-day surface water mass trend and GIA will be given briefly followed by a discussion of future opportunities and challenges in methodology, parameterization and data fusion.