An Approach To Derive An Along-track Mean Sea Surface Model From Topex/poseidon Altimetry
Abstract
When studying the temporal variability of sea surface heights derived from satel- lite altimetry, one must georeference several cycles to a common set of locations. In particular, one must compensate for the cross-track displacement between the ac- tual satellite ground track and the nominal one. This is usually done with the help of a full-coverage mean sea surface (MSS) model. Spatial resolution in these models is limited since they cover the entire ocean surface rather than the much smaller ground track neighbourhood. An along-track MSS model, restricted to a narrow band around the Topex/Poseidon (and Jason-1) nominal tracks but having a higher resolution, al- lows a more accurate cross-track compensation. Furthermore, the large number of T/P altimetry cycles available allows one to compute such an along-track MSS.
In the area surrounding the Cape Verde Islands the variability of the sea surface height is small compared to other areas of the Atlantic Ocean. The need for an accurate modelling of the cross-track compensation on the sea surface height is enhanced by the presence in this region of large geoid gradients. Such an area is therefore particularly suitable to test the advantages of the along-track MSS approach. Nine years of T/P altimeter data in that region have been analysed using standard pro- cessing techniques. The smoothing of the Topex ionosphere correction was performed using robust local regression filtering. Several recent tide models were applied and compared. The gridding of the along track MSS and the calculation of the associated uncertainties have been done with a novel method based on local regression interpo- lation. This paper describes the methods employed, presents the results obtained and com- pares this approach with a more conventional one using a full-coverage MSS.- Publication:
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EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.3320A