QUANTATAIVE ANALYSIS OF RELATIONSHIP BETWEEN ALOS PALSAR BACKSCATTER AND FOREST STAND VOLUME

Abstract

To estimate forest stand volume, topographic effects should be considered in Synthetic Aperture Radar (SAR) data processing, because most forests are located on mountainous areas in Korea. This paper shows how the effects on the ALOS Phased-Array L-Band SAR (PALSAR) backscatter in Kwangneung Experiment Forest can be reduced by gamma-nought γ^0.Regardless of coniferous and deciduous forests, the gamma-nought γ^0 values are always lower compared to the sigma-nought σ^0 values at HH and HV polarization for 58 standwise tree volume of the fore-slope (here, the west-facing slope) and are always higher in case of far-slope (here, east-facing slope).Comparison of the fore-slope with the far-slope, relating to the stand volume of the γ^0 and σ^0 values, demonstrates that the σ^0 values are significantly remarkable, while the γ^0 values are not. This means that the topographic normalized backscattering coefficient γ^0 can be used to estimate tree volume, independent of fore-slope and far-slope.Though the aforementioned two backscattering coefficients of γ^0 and σ^0 indicate L-band HH and HV saturations with tree volume observed at around 310 m^3ha^(-1), they increase with increasing trend with forest stand volume.These results show that stand volume retrieval of mountain forests can be improved by using topographic normalized backscattering coefficient of ALOS PALSAR data.