Temporal H/alpha Target Decomposition for Landslide Monitoring Using Ku-Band GB-SAR Time Series

We investigate the applicability of the entropy (H)/alpha ((alpha) over bar) target decomposition realized by the temporally averaged coherencymatrix, called temporal H/((alpha) over bar). We apply the temporal H/(alpha) over bar to ground-based synthetic aperture radar (GB-SAR) continuous monitoring data to characterize the scattering mechanism temporal change. As a case study, this work demonstrates the application of the temporalH/atechnique to landslide monitoring to detect and investigate the temporal scattering mechanism. The study acquired long-term GB-SAR polarimetric data over the postlandslide slope, Minami-Aso, Kumamoto, Japan. The study first investigated the property of the temporal H/(alpha) over bar parameters over selected land cover types by comparing it with that derived by spatial averaging (spatial H/(alpha) over bar) to explain the landslide-monitoring results. Also, the rainfall effects on the temporal H/(alpha) over bar parameters are demonstrated. The temporal H anda values increase up to 0.07 degrees and 13.54 degrees, respectively, when the rainfall rate is 52.5 mm/h. The time-series analysis of the temporal H/(alpha) over bar indicates an obvious temporal transition of the scattering mechanism and a change of the backscattering stationarity when a landslide occurs. The applicability of the temporal H/(alpha) over bar for the change-detection is discussed by comparing it with the classical spatial H/(alpha) over bar parameters.