Land based applications of multi-mission Satellite Radar Altimetry




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De Montfort University


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Peer reviewed


The success of the Radar Altimeter in determining sea surface heights over the open ocean is well known, with heights accurate to <5cm (Chelton et al., 2001); however land based applications are under developed. This is due to the complexity of the waveforms returned from land surfaces; retracking the waveform utilising an expert system approach can produce highly accurate orthometric heights.

This thesis compares the ERS-1 Geodetic Mission altimeter heights with the Shuttle Radar Topography Mission (SRTM) in order to assess the quality of the heights within the SRTM and to determine any areas of disagreement. To ensure that any phenomena discovered in the initial investigation are generic, and not limited to the ERS-1 Radar Altimeter (RA), a number of other altimeter missions were also compared to the SRTM dataset. One of the key characteristics of the altimeter is the ability to obtain accurate heights over inland water. In order to reduce the contamination of land within these results accurate masks of water extent must be created; a number of different approaches to this are investigated. The potential of sigma0 to contribute useful information to inland water measurement is also analysed. The totality of this research then furthered the aim of creating the most accurate Global Digital Elevation Model (GDEM) by enabling the generation of the ACE2 dataset. Extensive validation of the new GDEM was performed, and the global accuracy assessed, showing the extent to which the land surface heights of the Earth can currently be mapped. Exploring the synergies between the SRTM and radar altimeter height datasets then revealed additional information, such as the heights of rainforest canopy in the Congo and Amazon rainforests. Finally a look toward the capability of the next generation of altimeters to retrieve land surface height information was carried out by analysis of the CryoSat-2 Mission Performance Simulator (CRYMPS) scenarios generated as part of the SAMOSA project. The results show that the higher Pulse Repetition frequency (PRF) provided by the next generation of satellite radar altimeters will allow measurement of far finer-scale terrain features than is currently possible, and will continue to make a unique contribution to mapping the Earth’s land surfaces





Research Institute