Within a decade, imaging radar interferometry has matured to a widely used geodetic technique for measuring the topography and deformation of the earth. In particular the analysis and interpretation of the interferometric data requires a thorough understanding of the principles of the technique, the (potential) error sources, and the error propagation. This book reviews the basic concepts of radar, imaging radar, and radar interferometry, and revisits the processing procedure for obtaining interferometric products such as a digital elevation model or a deformation map. It describes spaceborne repeat-pass radar interferometry using a linear or Gauss-Markoff model formulation, which relates the interferometric observations to the unknown geophysical parameters. The stochastic part of the model describes the dispersion of the observations in terms of variances and covariances. Especially the influence of spatially correlated errors as induced by the satellite orbits and by atmospheric path delay are discussed. Mathematical models are presented that describe the spatial variability in the interferometric phase due to turbulent mixing of atmospheric refractivity and due to vertical atmospheric stratification. Using 52 SAR acquisations, a systematic inventory of the characteristics of atmospheric signal in the radar interferograms is performed, using complementary meteorological data for the interpretation. Scaling characteristics are observed, which can be conveniently used to describe the power spectrum and covariance function of the atmospheric signal. The final variance-covariance matrix for the radar interferometric data is presented, including these spatially varying error sources. A number of case studies on deformation monitoring, such as land subsidence, earthquake deformation, and artificial reflector movement serve as examples of the application of interferometry and its error sources. The feasibility of the technique for practical geodetic applications is evaluated in relation to the geophysical phenomena of interest, yielding rules-of-thumb for its utilization. Finally, a novel application of interferometry for atmospheric studies, termed Interferometric Radar Meteorology, is presented and discussed. Maps of the vertically integrated water vapor distribution during the radar acquisitions can be obtained with a fine spatial resolution and high accuracy. Several demonstration studies of the meteorological application are presented.
