Steric sea level variations inferred from combined Topex/Poseidon altimetry and GRACE gravimetry
David Garcia(1) , Guillaume Ramillien(2) , Alix Lombard(2) , and Anny Cazenave(2)
University of Alicante,
PO Box 99,
(2) Observatoire Midi-Pyrénées, 14, Avenue Edouard Belin, 31400 Toulouse, France
We have combined observations of global mean sea variations from Topex/Poseidon altimetry with averaged gravity variations over the oceans determined from the GRACE satellite data to estimate thermal expansion of the oceans over a 2-year plus period (March 2002 through July 2004). In effect, altimetry-derived global mean sea level change results from steric (thermal) effects and ocean mass change due to water exchange with atmosphere and continents. On the other hand, GRACE data over the oceans provides the ocean mass change component only. The paper first discusses the corrections to apply to the GRACE data as well as the ability of GRACE to measure the total water mass budget by comparing GRACE ocean data with non steric mean sea level variations. Then the steric contribution to the global mean sea sea level is estimated using GRACE and Topex/Poseidon data. Comparison with available thermal expansion estimates is performed.