HR: 1330h
AN: G32A-0725    [PDF]
TI: Global time-variations of hydrological signals from GRACE satellite gravimetry
AU: BRUNAU, O
EM: brunau@pinot.cst.cnes.fr
AF: LEGOS-GRGS/CNES, 18, Avenue Edouard Belin 31055 Toulouse cedex 01 FRANCE, Toulouse, 31055 France, Metropolitan
AU: * Ramillien, G
EM: Guillaume.Ramillien@cnes.fr
AF: LEGOS-GRGS/CNES, 18, Avenue Edouard Belin 31055 Toulouse cedex 01 FRANCE, Toulouse, 31055 France, Metropolitan
AU: Cazenave, A
EM: Anny.Cazenave@cnes.fr
AF: LEGOS-GRGS/CNES, 18, Avenue Edouard Belin 31055 Toulouse cedex 01 FRANCE, Toulouse, 31055 France, Metropolitan
AB: Successfully launched in mid-March 2002, the goal of the GRACE (Gravity Recovery \& Climate Experiment) satellite mission is to measure the spatio-temporal variations of the Earth's gravity field with high accuracy (~1 cm in terms of geoid height) and a spatial resolution of ~200-300 km for a nominal period of five years. The unprecedented precision of the GRACE mission will enable us to detect tiny time-variations of the gravity field related to global redistributions of fluid masses at the surface of the Earth. We preent here a new approach based on the generalized least-squares inverse method to unravel the different contributions of the main surface water reservoirs (atmosphere, oceans, total continental water storage) from time-series of monthly-mean GRACE geoids. The synthetic GRACE geoids were computed from outputs of global models of different climatic fields. Because of the non-uniqueness of the classical inverse problemes in gravity, independant information were added before inversion. In dividual geoid components of each hydrological contribution obtained as a solution of the inversion was then converted into a map of equivalent-water thickness using a linear filtering of the spherical harmonics of the geoid solutions. Validation consisted of comparaing the soil moisture solutions with independent information of in situ soil moisture time-series from Robock's database (Robock, 2002). Analysis of the errors after "de-correlation" suggests that the proposed inverse approach is able to recover global changes of water mass at time scales of at least a few weeks and accuracy of a few millimeters in water thickness.
DE: 1200 GEODESY AND GRAVITY
DE: 1223 Ocean/Earth/atmosphere interactions (3339)
SC: Geodesy [G]
MN: 2003 Fall Meeting