The propagation of orbital errors in the 3-Pass DInSAR processing

Orbital satellite state vectors are required not only to determine the baseline parameters, the offset of coarse registration but also to remove the reference phase and geocode the data to WGS84 in the 3-pass DInSAR processing. The quality of orbit limited to the current value of around 5-10 cm plays an important role in determining the precise deformation maps. Orbit errors in the along-track, the across-track and the radial directions can be represented by a noise baseline vector which leads to a convenient way of interpreting orbit errors. Under this transformation, we build the relationship between the residual reference phase and orbit errors in a concise way from which the approximate orbit precision can be estimated based on the residual reference phase. The analyses of the characteristics and influence of orbit errors indicate that the precision of height and deformation I s much more sensitive to errors in the across direction. A series of error propagating equations derived reveal the influence of orbital error on height is nearly 103 times higher than that on deformation, which is verified by processing the SAR data acquired by ERS-2 satellite over the site of the 1999 Chichi Taiwan earthquake with the ERS and DEOS orbits separately.