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Nouvelle approche pour l'extraction de paramètres géophysiques des mesures en altimétrie radar

Abstract : Radar altimeter echœs have a significant shape related to the surface that reflects them. In spatial oceanography, the processing of this shape enables to estimate the sea surface height, wind speed and significant wave height.

We propose here to reduce the noise level on the parameters estimated by taking advantage of the spatial correlation of data along the satellite tracks.
This noise reduction is applied on the echœs themselves before the estimation of the parameters thanks to a multidimensional approach. Packets of echœs are considered in order to build matrices of measures instead of considering each measure independently.
The main advantage of this method is to create different subspaces which enable to isolate the useful signal from the noise. Echœs rebuilt from the useful signal have a much lower noise although their geophysical information is conserved.
A special attention is given to the optimal choice of the dimension of the signal subspace. It is found with an empirical method on realist simulations and validated on real data from several altimeters.

Geophysical parameters are then estimated from the noise reduced echœs. Their precision is enhanced as high frequency noise is reduced.
This enables to follow higher frequency variability along the satellite track. This participates to the new orientation of altimetry heading towards local studies.
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Submitted on : Monday, January 14, 2008 - 3:26:57 PM
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Annabelle Ollivier. Nouvelle approche pour l'extraction de paramètres géophysiques des mesures en altimétrie radar. Traitement du signal et de l'image [eess.SP]. Institut National Polytechnique de Grenoble - INPG, 2006. Français. ⟨tel-00204475⟩

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