193-2 Potential of High-Resolution X- and C-Band SAR Sensors for Assessment of Biophysical Variables in Paddy Rice.

See more from this Division: ASA Section: Climatology & Modeling
See more from this Session: General Airborne and Satellite Remote Sensing: I (includes graduate student competition)
Tuesday, November 5, 2013: 10:35 AM
Marriott Tampa Waterside, Room 10
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Yoshio Inoue, National Institute for Agro-Env. Sciences, Tsukuba, Japan and Eiji Sakaiya, Aomori-ITC, Kuroishi, Japan
The objectives of this study were 1) to investigate the characteristics of high-resolution satellite SAR (synthetic aperture radar) sensors in X- and C-bands, and 2) to explore their unique capabilities in the assessment of key canopy variables in paddy rice. The X- and C-band SAR images were obtained by Cosmo-SkyMed, TerraSAR-X, and Radarsat-2 during the growing seasons of 2009-2012 in one of the major rice growing plains in Japan. All images were taken at the spotlight mode to ensure high spatial-resolution (1-2 m). Correlation analysis between backscattering coefficients (σ0) and biophysical variables showed clear and interesting results. In all SAR sensors, σ0 in rice canopies and nearby water surfaces were stable and consistent, although some obvious systematic shift was found between the X-band sensors. The X-band σ0 was not very sensitive to most of the other structural and morphological variables such as stem density and leaf size, but the σ0 during the maturing stage was best correlated with the panicle biomass. Results suggested a potential capability of X-band SAR for direct assessment of rice grain yield at regional scales from the space. The C-band σ0 had close positive relationships with the major volume-related variables such as LAI, plant height, and biomass. Structural variables such as leaf density and leaf size were moderately related to σ0. The response of σ0 to canopy biomass was expressed by an exponential equation with a high coefficient of determination, suggesting that the C-band σ0 may be able to detect the growth difference during the early stages. The close relationship of fAPAR with σ0 may be useful as a surrogate of the frequently-used NDVI-fAPAR relationship. SAR sensors with high spatial resolution would be useful for timely monitoring of biophysical variables, especially in monsoon regions, owing to their capability of all-weather observation.
See more from this Division: ASA Section: Climatology & Modeling
See more from this Session: General Airborne and Satellite Remote Sensing: I (includes graduate student competition)