Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 22, 2011
Publication Date: April 27, 2011
Citation: Kim, Y., Hong, S., Lee, H., Jackson, T.J., Bindlish, R., Kustas, W.P. 2011. Monitoring rice (oryza sativa L.) growth using multifrequency microwave scatterometers [abstract]. Abs. 24. BARC Poster Day. Technical Abstract: Microwave remote sensing can help monitor the land surface water cycle and crop growth. This type of remote sensing has great potential over conventional remote sensing using the visible and infrared regions due to its all-weather day-and-night imaging capabilities. In this investigation, a ground-based polarimetric scatterometer operating at multiple frequencies was used to continuously monitor the crop conditions of rice. Polarimetric observations at X-, C- and L-band were made every 10 minutes to study the effect of weather conditions on the microwave observations at various growth stages. The polarimetric scatterometer components were installed inside an air-conditioned shelter to maintain constant temperature and humidity during the data acquisition period. Backscattering coefficients for the entire rice growing season (from transplanting to harvesting) were compared with biophysical measurements. Backscattering coefficients for all bands gradually increased in accordance with rice growth data and decreased with a reduction of leaf area index (LAI) and fresh biomass. X-band backscattering coefficients observed dual-peak characteristics during rice growth stage (peak 1: 68 days after transplant; peak 2: 137 days after transplant) and grain water content was closely related to the X-band backscattering coefficients. L-band observations were significantly correlated to rice growth after the heading stage (84 days after transplanting) due to the double bounce scattering effect (the additional scattering resulting from the signal being reflected by the standing water under the rice). We also analyzed the relationship between the backscattering coefficients of each band and the various rice growth parameters. The correlation between biomass and backscatter decreased with increasing frequency. L-HH is the most preferable channel for the monitoring of total fresh weight (r=0.97), LAI (r=0.96) and plant height (r=0.88) while X-VV was the best for grain dry weight (r=0.94) and grain water content (r=0.93). The results of this investigation will be useful in determining the optimum microwave frequency and polarization necessary to estimate rice yield.