GRACE概要1.ppt

Conclusions Smoothed by 1000 km, GRACE data can pick up most major terrestrial water storage changes up to a few cm of water changes; GRACE data, at its current accuracy, agrees reasonably well with hydrological model predictions; GLDAS appears to out perform CPC when compared with GRACE data, in particular in the northern hemisphere. Given the progress GRACE made in the first 2 years, we may anticipate some major improvements from the next GRACE re-processing (e.g., GGM01 - GGM02, new ocean tide model, etc.). GRACE Home /grace/ /grace/ Low Degree Gravitational Changes from GRACE: Validation and Comparison with Earth Rotation and Geophysical Models Jianli Chen Center for Space Research, University of Texas at Austin Email: chen@ /personal/chen/ Independent determination of degree-2 Stokes coefficients ?C21, ?S21, and ?C20 from Earth rotation Observed Earth rotational excitations Atmospheric wind excitations Oceanic current excitations Independent determination of ?C21, ?S21, and ?C20 from atmospheric, oceanic, and hydrological models Atmospheric surface pressure Oceanic bottom pressure Continental water storage change Comparison with GRACE observations - validation interpretation Objectives Mass-induced Earth rotational excitations are proportional to ?C21, ?S21, and ?C20 via [Chen and Wilson 2003, Geoph. Res. Lett., Vol. 30 (24)] Theory where ?T=0, when considering mass load change on a sphere surface for a mass conserving Earth system (atmosphere, ocean, continental water+snow/ice sheet), and Observed Earth rotational excitations IERS combined EOP time series X, Y, LOD (C04) Daily average, 1962 to the present Trends removed Strong decadal signal in LOD removed Strong residual 5.6-year oscillation in LOD (? LOD-wind-current) removed using a 4-year period high-pass filter Ocean tide effects in LOD are removed using the IERS online interactive tools at http://hpiers.obspm.fr/eop-pc/analysis/excitactive.html Data and Proces