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1 Korean Journal of Remote Sensing, Vol.23, No.2, 2007, pp.45~52 Measurement of Backscattering Coefficients of Rice Canopy Using a Ground Polarimetric Scatterometer System Suk-Young Hong*, Jin-Young Hong**, Yi-Hyun Kim*, and Yi-Sok Oh** *National Institute of Agricultural Science and Technology, Rural Development Administration **Department of Radio Science and Communication Engineering, Hongik University Abstract : The polarimetric backscattering coefficients of a wet-land rice field which is an experimental plot belong to National Institute of Agricultural Science and Technology in Suwon are measured using ground-based polarimetric scatterometers at.8 and 5.3 GHz throughout a growth year from transplanting period to harvest period (May to October in 2006). The polarimetric scatterometers consist of a vector network analyzer with time-gating function and polarimetric antenna set, and are well calibrated to get VV-, HV-, VH-, HH-polarized backscattering coefficients from the measurements, based on single target calibration technique using a trihedral corner reflector. The polarimetric backscattering coefficients are measured at 30, 40, 50 and 60 with 30 independent samples for each incidence angle at each frequency. In the measurement periods the ground truth data including fresh and dry biomass, plant height, stem density, leaf area, specific leaf area, and moisture contents are also collected for each measurement. The temporal variations of the measured backscattering coefficients as well as the measured plant height, LAI (leaf area index) and biomass are analyzed. Then, the measured polarimetric backscattering coefficients are compared with the rice growth parameters. The measured plant height increases monotonically while the measured LAI increases only till the ripening period and decreases after the ripening period. The measured backscattering coefficientsare fitted with polynomial expressions as functions of growth age, plant LAI and plant height for each polarization, frequency, and incidence angle. As the incidence angle is bigger, correlations of L band signature to the rice growth was higher than that of C band signatures. It is found that the HH-polarized backscattering coefficients are more sensitive than the VV-polarized backscattering coefficients to growth age and other input parameters. It is necessary to divide the data according to the growth period which shows the qualitative changes of growth such as panicale initiation, flowering or heading to derive functions to estimate rice growth. Key Words : Polarimetric scatterometer, backscattering coefficient, rice canopy, LAI, biomass, plant height. syhong@rda.go.kr 45

2 Korean Journal of Remote Sensing, Vol.23, No.2, 2007 s s 46

3 Measurement of Backscattering Coefficients of Rice Canopy Using a Ground Polarimetric Scatterometer System g A ill = 2 (q, f) s ds () R 4 (q, f) S vv = [_ 2C 2( + ) + ( + C2 ) ( _ C 2 ) 2 m + C ( u vv )] 2 m 0 vv m u hh m 0 s0 hh S hh = [_ 2C 2( + ) + ( + C2 ) ( _ C 2 ) 2 m + C ( u hh )] 2 m 0 hh m u vv m 0 s0 vv S vh = [ 2 m u vh + m u 2C2 hv _ ( + C 2 ) ( _ C 2 ) 2 m + ( u vv m u hh m m )] 0 0 s0 vv hh S hv = [ 2 m u hv + m u 2C2 vh _ ( + C 2 ) ( _ C 2 ) 2 m + ( u vv m u hh m m )] 0 0 s0 vv hh m 0 2m 0 2 a a, C = ( a ) (2) m 0 m 0 22 m 0 vh m 0 hv m u vh m 0 vh m u vh m 0 vh m u hv m 0 hv m u hv m 0 hv m 0 hv m 0 vh 47

4 Korean Journal of Remote Sensing, Vol.23, No.2, 2007 s 0 m 0 pq m U pq s 0 4p pq = Ω S pqω 2 (3) A ill, pq 48

5 Measurement of Backscattering Coefficients of Rice Canopy Using a Ground Polarimetric Scatterometer System Fig.. Backscattering coefficients of rice growth as a function of time at different wavelengths, incidence angles, and polarization. 49

6 Korean Journal of Remote Sensing, Vol.23, No.2, 2007 Table. Correlations of radar backscattering to rice growth..95 GHz (L-band)5.3 GHz (C-band).95 GHz (L-band) 5.3 GHz (C-band) vv-pol hh-pol hv-pol vv-pol vh-pol hh-pol vv-pol hv-pol hh-pol vh-pol hv-pol vv-pol vh-pol hh-pol hv-pol vh-pol Plant Height Overall LAI TFW TDW Plant Height Heading st. LAI TFW TDW Plant Height Panicle Ini. LAI TFW TDW Plant Height Overall LAI TFW TDW Plant Height Heading st. LAI TFW TDW Plant Height Panicle Ini. LAI TFW TDW Plant Height Overall LAI TFW TDW Plant Height Heading st. LAI TFW TDW Plant Height Panicle Ini. LAI TFW TDW Plant Height Overall LAI TFW TDW Plant Height Heading st. LAI TFW TDW Plant Height Panicle Ini. LAI TFW TDW

7 Measurement of Backscattering Coefficients of Rice Canopy Using a Ground Polarimetric Scatterometer System Fig. 2. Relationship between radar backscattering coefficients and rice growth at 50 degree incidence angle. 5

8 Korean Journal of Remote Sensing, Vol.23, No.2, 2007 Hong, S. Y., S. H. Hong, and S. K. Rim, Relationship between Radarsat backscattering coefficient and rice growth, Korean J. Remote Sensing, 6(2): Inoue, Y., Remote sensing and GIS for spatial assessment of agro-ecosystem Dynamics. In Proc. of the First Int l Symposium on Assessing and Rational Management of the Agro-Ecosystem for Clean and Friendly Future Environment, October 22, 2003, Seoul, Korea, pp.-98. Sarabandi, K. and F. T. Ulaby, 990. A Convenient Technique For Polarimetric Calibration of Single-Antenna Radar Systems, IEEE Trans. Geosci. Remote Sensing, 28(6):

04김이현(31~44)ok

04김이현(31~44)ok Korean Journal of Remote Sensing, Vol.25, No.1, 2009, pp.31~44 Estimation of Paddy Rice Growth Parameters Using L, C, X-bands Polarimetric Scatterometer Yi-Hyun Kim*, Suk-Young Hong*, and Hoonyol Lee**

09È«¼®¿µ 5~152s

09È«¼®¿µ5~152s