X-band extinction in boreal forest: Estimation by using E-SAR POLInSAR and HUTSCAT

In this paper we study the extinction coefficient of boreal forest by utilizing airborne E-SAR X-band POLInSAR and HUTSCAT X-band profiling scatterometer measurements. By combining E-SAR VV-pol coherency with HUTSCAT tree height measurements we calculate forest extinction coefficients by RVoG model inversion and compare the results with extinction values obtained from HUTSCAT measurements. For retrieval of the extinction coefficient we propose robust RVoG model inversion procedure and discuss the model inversion conditions. Our results show, that extinction coefficient for boreal forest is quite low even for X-band, especially from nadir looking instruments. The extinction coefficient of forest canopy retrieved from HUTSCAT measurements is 0.15 dB/m and retrieved from E-SAR and HUTSCAT measurements is 0.9 dB/m.