  This paper introduces a novel scheme to progressively estimate
interferometric phases from a stack of synthetic aperture radar (SAR) images.
The scheme is shown to yield comparable performance to full-covariance
algorithms for a realistic decorrelation scenario. The implementation is suited
for continuous processing and updating of phase products, without compromising
long-term phase accuracy. It also limits the requirements in terms of data
transfer between archive and processing facility, a significant issue for
processing large archives of SAR data.
