An Enhanced Ocean and Coastal Zone Retracking Technique for Gravity Field Computation
Satellite radar altimetry has been key to the improvement of geoid and gravity models. Of prime importance to this is obtaining stable and accurate height estimates over the ocean. This is especially difficult over coastal zones due to the non-Brown model nature of the waveforms.
Following a study of existing ocean retracking techniques and analysis of results from the Berry expert system, an enhanced retracking system has been developed which gives more consistent results compared with conventional techniques over both the open ocean and coastal zones. This paper presents results from retracked ERS-1, ERS-2 and Envisat data comparing these against existing methods and presenting details of enhancements made.
The authors would like to thank ESA for the ERS1-GM, ERS-2 and EnviSat datasets and TU Delft for the RADS dataset.
- Andersen, O., P. Knudsen, P.A.M. Berry, J.A. Freeman, S. Kenyon, and R. Trimmer (2007). Refining global marine gravity prediction from satellite and ships, DNSC06 global marine gravity field and associated bathymetry. Envisat Symposium 2007, Montreux, Switzerland 23–27 April 2007, ESA Pub. SP-636 2007.Google Scholar
- Benveniste, J., S. Baker, O. Bombaci, C. Zeli, P. Venditti, O.Z. Zanife, B. Soussi, J.P. Dumont, J.P. Stum, and M. Milagro-Perez (2002). ENVISAT RA-2/MWR Product Handbook, Issue 1.2, PO-TN-ESR-RA-0050, European Space Agency, Frascati, Italy.Google Scholar
- Berry, P.A.M., A. Jasper, and H. Bracke (1997). Retracking ERS-1 altimeter waveforms over land for topographic height determination: an expert system approach. ESA Pub. SP-414, 1, 403–408.Google Scholar
- Berry, P.A.M., J.D. Garlick, J.A. Freeman, and E.L. Mathers (2005). Global inland water monitoring from multi-mission altimetry. Geophys. Res. Lett., 32(16), L16401, DOI: 10.1029/2005GL022814.Google Scholar
- Capp, P. (2001), Altimeter waveform product ALT.WAP compact user guide, Issue 4.0, PF-UG-NRL AL-0001, Infoterra Ltd., UK.Google Scholar
- Challenor, P.G. and M.A. Srokosz (1989). The extraction of geophysical parameters from radar altimeter return from a nonlinear ocean surface. In: Brooks S.R. (ed), Mathematics in remote sensing. Institute of Mathematics and its Applications, Clarendon Press, pp. 257–268.Google Scholar
- Naeije, M., E. Schrama, E. Doornbos, and R. Scharroo (2006). The role of RADS in building the 15-year altimeter record. Proceedings of Symposium on 15 years progress in RA, 13–18 March 2006, Venice Italy, ESA SP 614 July 2006.Google Scholar
- Scharroo R., E. Schrama, M. Naeije, and J. Benveniste (2000). A recipe for upgrading ERS altimeter data, European Space Agency, (Special Publication) ESA SP, 461, pp. 1300–1309.Google Scholar