Perturbation caused by cloud in ERS SAR interferogram

In repeat-pass SAR interferometry, errors by the tropospheric radar phase delay has been pointed out. We analyze ERS SAR data pairs covering the Kanto Plains, which is a region including Tokyo, Japan. Fringe features that are independent from actual deformations are found from generated interferograms. The fringe patterns are depends on the data; same feature appears on the interferograms generated from the same data. One of the significant patterns is detected in the interferograms from data obtained in August 1999, all of the interferograms by this data contain same fringe feature. A SPOT HRV image acquired 18 minutes after the SAR data reveals patterns of cloud distribution that are similar to the fringe features in the interferograms. It shows a possibility for cloud-induced perturbations in radar signals. Optical sensor imagery with a spatial resolution equivalent to that of the SAR imagery is useful for the evaluation of interferometric fringes.