Temporal H/alpha target decomposition for landslide monitoring using Ku-band GB-SAR time series

We investigate the applicability of the entropy (H)/ alpha (α¯) target decomposition realized by the temporally averaged coherency matrix, called temporal H/(α¯). We apply the temporal H/α¯ 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 temporal H/α¯ technique 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/α¯ parameters over selected land cover types by comparing it with that derived by spatial averaging (spatial H/α¯) to explain the landslide monitoring results. Also, the rainfall effects on the temporal H/α¯ parameters are demonstrated. The temporal H and α¯ values increase up to 0.07^◦ and 13.54^◦, respectively, when the rainfall rate is 52.5 mm/h. The time-series analysis of the temporal H/α¯ 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/α¯ for the change-detection is discussed by comparing it with the classical spatial H/α¯ parameters.