IGPP Seminar Series

Seasonal and Interannual Surface Mass Variations from Multi-Satellite Geodetic Data: A Global Inverse Approach

by Dr. Xiaoping Wu
JPL

Abstract

Global surface mass variations including non-steric sea level change, ice mass imbalance, and land hydrology have significant implications on climate change and the lives of the world community. With multiple time scales, these variations perturb Earth's external gravity field, load the solid Earth to cause crustal deformation, and drive the center of mass of the total Earth system to move with respect to the geometric center of the solid Earth (geocenter motion). Accurately measured by GRACE gravity mission, GPS, Topex/Jason, and satellite laser ranging (SLR), these geodetic signatures contain overlapping and complementary information. Comparing and combining them can achieve valuable cross- calibration/validation and global surface mass monitoring with complete spatiotemporal coverage, higher resolution and accuracy. Focusing on seasonal and interannual time scales when solid Earth deformation is largely elastic, we solve for full spectrum spherical harmonic coefficients of surface mass re-distribution up to degree and order 50. A hybrid global inverse method based on singular value decomposition is applied to GRACE and GPS data as well as a Topex/Jason and other data assimilated ocean bottom pressure (OBP) model separately and in combination. A global pattern of agreement has emerged between the totally independent gravity and load deformation based techniques. The combination of GRACE/GPS/OBP has also yielded high-quality monthly degree-1 surface mass estimates with an unprecedented equivalent geocenter motion precision of < 0.5 mm in all three components. We will also discuss global and regional results including mean sea level, average changes in Antarctica/Greenland, and significant interannual mass variations.
Tuesday, 03 October 2006
3845 Slichter Hall
Refreshments at 3:45 PM
Lecture at 4:00 PM