CONTRIBUTION OF ENVISAT RA-2 TO GLOBAL SRTM EVALUATION WITH ALTIMETER DATA

摘要

Altimeter data from the ERS-1, ERS-2 and Envisatrnmissions have been reprocessed using a rule-basedrnexpert system to yield hundreds of millions of heightrnmeasurements over the earth's land surface. This uniquerndataset has been used in a global scale evaluation of thernShuttle Radar Topography Mission (SRTM). Whilstrnanalysis with ERS RA-1 data has given good resultsrnover relatively flat terrain, the inability of the altimeterrnto maintain lock over mountainous terrain has severelyrnlimited independent evaluation of global and regionalrnDEMs using altimetry. The Envisat RA-2 uses threernmodes of operation to maintain lock over even extremernterrain. This presents the first opportunity to examinernthe performance of DEMs with altimeter-derivedrnheights over a significant proportion of the earth's landrnsurface. This paper presents results from a global scalernstudy comparing Envisat RA-2 Ku-band retrackedrnheights with the NASA SRTM dataset, and evaluatesrnthe potential for Envisat RA-2 to contribute to globalrnterrain mapping.