Large-scale fine-resolution products of forest disturbance using new approaches from spaceborne SAT interferometry

Abstract

Spaceborne SAR interferometry (InSAR) has the potential of detecting forest change on a global scale with fine (meter-level) spatial resolution as well as on a monthly/weekly basis under all weather conditions. This is significant to characterize the land use change and its impact on climate change. In this paper, both single-pass and repeat-pass SAR interferometry from spaceborne sensors are combined in order to detect and quantify (with Normalized RMSE 30%) forest disturbance at a large scale (dozens of kilometers) however with a fine spatial resolution (< 1 hectare) based on two newly developed approaches. The singlepass InSAR approach is not only able to detect forest disturbance but also capable of characterizing meter (or even sub-meter) level change of forest phase-center (mean) height due to forest growth and/or degradation. The methodology described in this paper can be considered as complimentary tools and thus can be combined with the existing PolInSAR technique (that has been widely used for retrieving forest height from single-pass SAR interferometry). These methods are extensively validated with the past and current spaceborne single-pass and repeat-pass InSAR missions (i.e. JAXA’s ALOS-1, ALOS-2 and DLR’s TanDEM-X) over subtropical forests in Australia as well as tropical forests in Brazil. Such techniques also serve as observing prototypes for the fusion of the future spaceborne InSAR missions (such as NASA-ISRO’s NISAR and DLR’s TanDEM-L).