HR: 0830h
AN: G21C-0280    [PDF]
TI: Combination of altimeter data, tide gauge data and ocean climatology to reconstruct sea level change.
AU: * Schrama, E
EM: schrama@geo.tudelft.nl
AF: TU Delft/DEOS, PO box 5058, Delft, 2600 GB Netherlands
AB: This contribution deals with the combination of satellite altimetry data from the TOPEX and JASON-1 altimeter, in-situ tide gauge data and climatologic data to reconstruct long periodic variations and systematic trends in the sea level. The approach we take is to calibrate in a relative sense both altimeter systems which have operated in tandem mode during the first half year of the JASON-1 mission. As a result we find a relative altimeter bias of about 10 cm. This value is determined from the JASON-1 interim geophysical data records (IGDRs) that come with a sea state bias algorithm. Then we evaluate the absolute altimeter bias with a global network of tide gauges. This enables us to determine the sea level trend of which we provide a number of estimates including a land motion term of the involved gauges. Next we recognized that the global sea level trend is affected by the presence of annual and semi-annual cycles and the 1997-1998 ENSO. The annual cycle turns out to be related to steric variations in the oceans as can be shown by comparing the signal to a steric annual cycle reconstructed from a ocean climatologic atlas. In a similar way this atlas allows us to estimate the global thermosteric trend signal in the oceans for which we now find 1.5 mm/yr in the form of a global eustatic sea level rise.
DE: 1223 Ocean/Earth/atmosphere interactions (3339)
DE: 4215 Climate and interannual variability (3309)
SC: Geodesy [G]
MN: 2003 Fall Meeting