Toward a homogeneous ERS-1 / TOPEX/POSEIDON data set
P.Y. Le Traon (CLS, France)
TOPEX/POSEIDON and ERS-1 simultaneously measure the ocean surface topography. The two satellites have complementary space-time sampling but different accuracies.
ERS-1 data can be enhanced significantly by the more accurate simultaneous TOPEX/POSEIDON data. This enhancement provides a homogeneous data set for the satellites. It could be used to map sea level variations or the mean ocean surface with fine resolution and very high accuracy.
A pilot experiment has shown the feasibility of such an approach. An ERS-1 cycle (cycle 9 of ESA OPR data distributed by CERSAT) was processed and the method based on global minimization of TOPEX/ POSEIDON / ERS-1 crossover differences [Le Traon et al., 1994] validated. The enhancement of ERS-1 data is plainly visible on the accompanying figures, which show the reduction in difference at the ERS-1 / ERS-1 crossover points before and after orbit correction from TOPEX/POSEIDON data.
AVISO distributes the processed ERS-1 cycle as a simplified file, comprising the corrected altimeter heights and the orbital error.
The file is for basic use of the data. The test CD-Rom is available to anyone interested. We will process all the ERS-1 data (35-day phase and 168-day phase) by this method, using the best available tide models based on TOPEX/POSEIDON data.
References :
- Le Traon, P. Y., P. Gaspar, F. Bouyssel, and H. Makhmara, 1995. Use of TOPEX/ POSEIDON data to enhance ERS-1 data, J. Atmos. Ocean Tech., Vol.12, Issue 1,161-170.
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