Wednesday 24 August 2005

GP2
0830-1000 hours

222
Satellite altimetry: multi-mission cross calibration
Bosch, Wolfgang¹
1 DGFI, Munich, Germany
Author email: bosch@dgfi.badw.de
Multi-mission satellite altimetry provides a unique opportunity to perform an innovative utmost rigorous cross-calibration of all satellites operating simultaneously. Data from TOPEX, TOPEX-EM, ERS2, GFO, ENVISAT and Jason1 is used to compute - in all combinations - nearly simultaneous single and dual satellite crossovers that are unaffected by sea level variability. The total set of crossovers provides a rather dense sampling of the orbits of all satellites and realizes a rigid network with high redundancy to obtain - by a discrete crossover analysis technique - a reliable estimate of the radial error components. The analysis is performed for a sequence of 10 day periods (cycle 96-450 of TOPEX) with 2 days overlap to neighbouring periods. For all satellites the error estimates for the radial component exhibit significant geographical pattern - even for TOPEX for which the sum of all error components is forced to be zero. Mean error patterns are investigated in detail as they indicate geographical correlated errors induced from gravity field uncertainties. The error components are also taken to calculate a time series of relative range biases and relative geo-centre offsets between all altimeter missions.

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