Noriyuki Kawano

Dependency of forest biomass on full Polarimetric parameters obtained from L-band SAR data for a natural forest in Indonesia

Aboveground (AG)-biomass was estimated from a field biomass collection and LiDAR observations for a natural forest in Indonesia. The derived AG-biomass data were plotted against full polarimetric parameters calculated from Polarimetric and Interferometric Airborne Synthetic Aperture Radar L2 (Pi-SAR-L2) and PALSAR data. The α°-AG-biomass curve shows saturation by around 100 tons/ha, while for entropy, correlation is observed up to 200 tons/ha. The largest coefficient of determination (R2 = 0.2348) was observed for the range with AG-biomass of more than 100 tons/ha for the relation between AG-biomass and entropy. The α°HV-biomass plot derived from PALSAR data shows smaller variance in the dry season than in other seasons, indicating that dry season data is preferable for a more accurate estimate of AG-biomass.

Flood disaster monitoring with ALOS/PALSAR observation

We investigate an effective algorithm to identify flood-inundated area with ALOS/PALSAR observations. Radar cross section from water surface is generally smaller than that from ground surface without water, which derives larger differences of radar cross section in flood-inundated area because there is no water in this area before disaster. Variances of differences in 3×3 pixels are also enough to identify flood-inundated area, and more effective algorithm to identify flood-inundated area will be obtained by taking radar cross section differences and variances of differences into account.

PiSAR-L2 observation of agricultural area damaged by seawaterduring the Great East Japan Earthquake in 2011

On March 11, 2011, a massive earthquake occurred on the eastern coast of Japan. The magnitude 9.0 quake was the most powerful ever recorded in Japan. The height of the tsunami that followed the earthquake was estimated to be more than 10 m. The water reached a few kilometers inland and resulted in thousands of casualties as well as serious damage to buildings and agricultural areas along the coastline. Several PiSAR-L2 observations were carried out in these tsunamiaffected areas from April to September in 2012, and field experiments were performed in agricultural areas that had been damaged by seawater. The complex dielectric constant and the electrical conductivity of the soil were measured to estimate the soil’s salinity. The imaginary part of the dielectric constant for a tsunami-damaged area 0.7 km from the coastline was shown to be 37.1 at 1 GHz, and the electric conductivity was shown to be 7.8 mS/cm. These values exceeded those from non-damaged inland areas. One of the full polarimetric parameters, co-polarization backscattering ratio (σ0HH/σ0VV) derived from PiSAR-L2 data, were examined and compared for damaged/non-damaged areas. The analysis indicates that the higher-salinity area was well detected by σ0HH/σ0VV. However, water areas and flat surfaces covered by gravel exhibit similar characteristics, and this may result in the false detection of salt-affected agricultural areas.