Large-scale forest height mapping in the northeastern us using l-band spaceborne repeat-pass sar interferometry and gedi lidar data

This paper presents a promising fusion prototype for forest stand height inversion using L-band spaceborne repeat-pass SAR interferometry (InSAR) and spaceborne Global Ecosystem Dynamics Investigation (GEDI) LiDAR measurements. NASA's GEDI mission provides sparsely but extensively distributed LiDAR measurements which could serve as ample calibration samples to improve the forest height estimates based on InSAR information and semi-empirical scattering model. Based on previous efforts, this paper further removed the assumptions that were made given by the limited availability of calibration samples at that time, and developed a new inversion approach based on a global-to-local two-stage fitting scheme. Making good use of local GEDI samples in this approach allows a finer characterization of temporal decorrelation pattern and thus higher accuracy of forest height inversion. This approach is validated at the Howland Forest in Maine, U.S. by using ALOS InSAR and GEDI LiDAR data, where the estimates achieve a RMSE of 3.8m at a sub-hectare spatial resolution (e.g., 0.81 ha). The above experimental results demonstrates a promising prototype towards a large-scale forest height mapping using existing and future spaceborne L-band InSAR missions (JAXA's ALOS-1/2, China's L-SAR, NASA-ISRO's NISAR), as well as spaceborne LiDAR missions (e.g. NASA's GEDI, JAXA's MOLI and China's TECIS).