IGCP 565 Project Workshop

IGCP 565 Workshop 1: Science of geodetic monitoring of the hydrological cycle

Abstract:

Inversions of Geodetic Observations: Current Resolution, Accuracy and Challenges
Xiaoping Wu
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

Ice ages, Late-Pleistocene deglaciation, present-day non-steric sea level change, Greenland and Antarctic ice mass fluctuations and land hydrological cycles are all prominent examples of global surface mass variations in the fluid layer of the Earth. Physically distinguishable geodetic signatures of such variations including gravity, ocean topography and displacement of the solid Earth surface are currently measured with ever increasing precision by the GRACE, Topex/Jason/OSTM satellite missions and surface geodetic networks of SLR/VLBI/GPS. The complementary and overlapping information content contained in these data makes it very clear that data combination offers the best chance for signature separation, more complete spatiotemporal coverage and resolution, and cross technique data validation. In this presentation, we will demonstrate quantitatively the power of such data combination in providing a global monitoring capability with more complete spatiotemporal spectrum, and enhanced resolution, and accuracy. The time rates of change in many geodetic data contain a multitude of signatures due to present-day surface mass trend, glacial isostatic adjustment (GIA) and tectonic motions. Data combination in this case offers a unique chance to separate and resolve them and allow us to understand the different underlying geophysical causes better. We will show that although some separation can be achieved for the secular signatures, a better understanding requires continued missions, significant ground infrastructure improvement, and more data in strategic locations.