Impacts of geoid height on large-scale crustal deformation mapping with InSAR observations

Li, P., Li, Z., Shi, C., Feng, W., Liang, C., Li, T., Zeng, Q. and Liu, J. (2013) Impacts of geoid height on large-scale crustal deformation mapping with InSAR observations. Chinese Journal of Geophysics (Chinese Edition), 56(6), pp. 1857-1867. (doi: 10.6038/cjg20130608)

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Abstract

An ellipsoidal height datum (e.g. WGS84) is required in SAR Interferometric processing, whilst DEMs are often referenced to a geoid datum (e.g. EMG96). Therefore, geoid height error is introduced due to the inconsistency of height datums in InSAR derived displacement maps. In this paper, the relationship between geoid heights and uncertainties in InSAR displacements is investigated using 27 scenes of Envisat ASAR ScanSAR images and 44 scenes of Image-mode images covering the western Altyn Tagh Fault, northern Tibetan Plateau. A typical error of 8.8 m in SRTM DEM leads to 3mm uncertainty in an InSAR interferogram with a perpendicular baseline of 100m, whilst a geoid height of 20m can result in 10mm uncertainty. Geoid height ranges from one place to another, and are highly correlated with topography. The impacts of geoid height on InSAR displacements increase with perpendicular baselines, but SAR images with a small perpendicular baseline may not be available in some cases. In addition, it may also not always be feasible to use a best-fitting plane to remove the impacts of geoid height. It is thus highly recommended in this paper that DEMs with an ellipsoidal height datum should be employed in interferometric processing, particularly when long-wavelength crustal deformation is targeted.

Item Type:Articles
Keywords:SAR interferometry; Wide-Swath InSAR; Geoid Height; Crustal Deformation´╝ŤAltyn Tagh Fault
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Li, Dr Zhenhong
Authors: Li, P., Li, Z., Shi, C., Feng, W., Liang, C., Li, T., Zeng, Q., and Liu, J.
Subjects:G Geography. Anthropology. Recreation > GA Mathematical geography. Cartography
G Geography. Anthropology. Recreation > GB Physical geography
Q Science > QE Geology
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Research Group:Earth Systems Research Group - Geomatics
Journal Name:Chinese Journal of Geophysics (Chinese Edition)
Publisher:Kexue Chubanshe
ISSN:0001-5733

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
605761Polarimetric synthetic aperture radar image processing for rapid assessment of earthquake hazard damageZhenhong LiRoyal Society of Edinburgh (ROY_SOC_ED)443570/NNS/INTSCHOOL OF GEOGRAPHICAL & EARTH SCIENCES
513031GAS: Generic Atmosphere Solutions for radar measurementsZhenhong LiNatural Environment Research Council (NERC)NE/H001085/1SCHOOL OF GEOGRAPHICAL & EARTH SCIENCES