Systematic Interferometric Phase Biases and their Impact on Earth Surface Deformation Monitoring

In this work we scrutinze the reliability of multilooked interferograms for deformation analysis. Designing a simple approach in the evaluation of the accuracy of the estimated deformation signals, we reveal a prominent bias in the deformation velocity maps. The bias is the result of propagation of small phase error of multilooked interferograms through the time series and can sum up to 6.5 mm/yr in case of using the error prone short temporal baseline interferograms. We further discuss the role of the phase estimation algorithms in significant reduction of the bias and put forward the idea of a unified intermediate InSAR product for achieving high-precision deformation monitoring.