Optimization technique of asymmetric-order vegetation isoline equations

This study investigated an optimization technique for improving the inter-band reflectance relationship known as the vegetation isoline equations. A single factor was introduced into the recently developed vegetation isolines [Miura et al. 2015] to decompose the higher-order interaction terms of photons between the canopy layers and soil surfaces. A set of numerical experiments based on the canopy radiative transfer (RT) model revealed that the error in the optimized isoline equation could be reduced by approximately 80 percent relative to the error calculated for the asymmetric-order isoline without optimization. This accuracy improvement generally held for combinations of red and near-infrared wavelengths. These results indicated that the optimized form of the vegetation isoline could be used as an emulator for the RT model in the context of inverse problems for parameter retrievals.