Estimation of boreal forest biomass from two-level model inversion of interferometric TanDEM-X data

A new model for aboveground biomass estimation from forest height and canopy density estimates obtained from the inversion of a two-level model (TLM) is presented and studied using data from the hemi-boreal test site Remningstorp, situated in southern Sweden. Three bistatic-interferometric TanDEM-X acquisitions from the summers of 2011, 2012, and 2013 and with heights-of-ambiguity (HOAs) 49 m, 32 m, and 63 m, respectively, are used. An external, high-resolution digital terrain model (DTM) is used as ground reference during interferogram flattening. Model parameters are estimated for each acquisition separately, and the model is evaluated on all three acquisitions, to examine both its explanatory and predictive values. Residual root-mean-square errors (RMSEs) are 14%-19% and the model explains 67%-84% of the variance in the data. Prediction RMSE is 20% for the two images with the highest HOA, but much higher for the third image.