Assessment and Correction of the Global 3 arc-second SRTM DEM Using Multi-mission Radar Altimetry
James Garlick(1) and Philippa Berry(1)
De Montfort University,
The release of the Shuttle Repeat Topographic Mission (SRTM) C-band data set provides a near-global 3 arc-second resolution DEM. Global scale validation of these data is problematic since available ground truth are patchy and of variable quality. Using a unique database of heights derived from ERS-1, ERS-2, ENVISAT, Topex and Jason-1 radar altimeters, including over 54 million height measurements obtained from the ERS-1 Geodetic Mission, a global validation of the SRTM data set has been performed. The results show that these data sets are generally in very good agreement over much of the Earth's land surface. However, geographically correlated patterns of differences between the two data sets have been observed. Many of these anomalies are caused by differences in the acquisition technique of the instruments, for example the SRTM is sensitive to vegetation where as the Radar Altimeter is not.
This paper presents the results of the continued work on the assessment of the differences between these two data sets, and the use of the altimeter data where appropriate to correct the SRTM derived heights. Of particular note is the ability of the RA-2 to maintain lock over extreme terrain and thus allow assessment and correction of SRTM data obtained over mountainous topography. The results demonstrate the effectiveness of the altimeter data in assessment, validation and error-correction of space derived DEM data sets.