Estimationg rice growth parameters using X-band scatterometer data IGARSS2010, Honolulu Hawaii, July 25-30, 2010 Estimationg rice growth parameters using X-band scatterometer data Yihyun Kim1*, S.Young Hong1, Eunyoung Choe1 and Hoonyol Lee2 1 National Academy of Agricultural Science, RDA, Korea 2 Department of Geophysics, Kangwon National University, Korea  

Contents Background 1 2 3 4 Material and Methods Results Conclusion

Background Rice is one of the major crops in Korea Microwave radar can penetrate cloud cover regardless of weather condition Ground-based polarimetric scatterometer has advantage of monitoring crop conditions with full polarization and various frequencies Plant parameters such as LAI, biomass, plant height are highly correlated with backscattering coefficients ENVISAT SAR data (5.3 GHz, hh-, hv-polarizations, and incidence angles between 28.5° and 40.9°) to monitor rice growth and compared the data with simulation results (Le Toan et al, 1997)

Background RADARSAT data (5.3 GHz, hh-polarization, and incidence angles between 36° and 46°) was analyzed for monitoring the rice growth in Korea (Hong et al,2000) Backscattering coefficients from a ground scatterometer are often affected by weather condition the necessity of near-continuous automatic measurement has arisen by the experiment in 2007 (Kim et al, 2008)

Objective To analyze scattering characteristics of paddy rice obtained from L, C, X-band automatic scatterometer system Relationship between backscattering coefficients in L, C, X-band and plant parameters with full polarization Prediction of rice growth parameters using backscattering coefficients in L, C, X-band

Study site - An experimental field at NAAS, Suwon, Korea Testing varieties : Chuchoungbyeo The size field : 660m2

Materials and Methods L, C, X-band automatic scatterometer system C-band L-band Measurement Interval : 1 per 10 minutes

Dual polarimetric horn Materials and Methods Specification of the L, C, X-band automatic scatterometer system Specification L-Band C-Band X-Band Center frequency 1.27GHz 5.3GHz 9.65GHz Bandwidth 0.12GHz 0.6GHz 1GHz Number of frequency points 201 801 1601 Antenna type Dual polarimetric horn Antenna gain 12.4dB 20.1dB 22.4dB Range resolution 1.25m 0.25m 0.15m Wavelength 0.23m 0.056m 0.031m Polarization HH, VV, HV, VH Platform height 4.16m

Radar backscattering measurement - Between before transplanting(17 May, 2009) and harvesting stage(12 Oct, 2009) Growth data collection - Leaf Area Index, Plant height, Fresh and Dry weight etc. Transplant stage (mid-May) Panicle formation stage (mid-July) Heading stage (mid-Aug) Harvesting stage (mid-Oct)

Backscattering coefficients of X-band the follow expression Calculation of backscattering coefficients (apply to radar equation) Backscattering coefficients of X-band the follow expression

Results Temporal variations in growth parameters during rice growth heading stage <Plant height> <Leaf Area Index>

Results Temporal variations in growth parameters during rice growth heading stage <Fresh biomass> <Dry biomass>

Results Temporal variations of backscattering coefficients at polarization and incident angle 45° for the L-band booting stage ~ heading stage (most active rice growth period)

Results Temporal variations of backscattering coefficients at polarization and incident angle 45° for the C-band

Results Temporal variations of backscattering coefficients at polarization and incident angle 45° for the X-band

Results Relationship between backscattering coefficients at L, C, X-band and plant variables L-band VV HH HV Incident angle Plant Height LAI Tfw (g/m2) Gdw height 45 0.80** 0.91*** 0.90*** -0.78** 0.89*** 0.98*** 0.96*** -0.74** 0.79** 0.93*** -0.62* C-band VV HH HV Incident angle Plant height LAI Tfw (g/m2) Gdw 45 0.60* 0.86** 0.75** -0.78** 0.70** 0.92*** 0.83** -0.83** 0.77** 0.91*** 0.89*** -0.72** X-band VV HH HV Incident angle Plant height LAI Tfw (g/m2) Gdw 45 0.63* 0.66* 0.73** 0.94*** 0.72** 0.81** 0.84** 0.79** 0.68* 0.83** 0.70*

Results Optimum condition for estimation of rice growth parameters Band Polarization R2 Plant height(cm) L-band HH R2=0.86*** Leaf Area Index R2=0.96*** Fresh Biomass(g/m2) Above ground R2=0.94*** Grain X-band VV R2=0.91*** Grain dry weight(g/m2)

Results Prediction of Leaf Area Index using backscattering coefficients(L-band, HH) y = 0.8739x + 0.4459 R2 = 0.95*** RMSE = 0.2346

Results Prediction of Biomass using backscattering coefficients (L-band, HH) y = 1.0028x – 0.5471 R2 = 0.95*** RMSE = 8.5412

Results Prediction of Grain dry weight using backscattering coefficients (X-band, VV) y = 1.1099x – 1.3067 R2 = 0.96*** RMSE = 1.7685

Conclusions Backscattering coefficients of rice crop were investigated with an automatically -operating ground-based scatterometer The temporal variations of the backscattering coefficients of the rice crop at L, C, X-band during rice growth period HH-polarization backscattering coefficients higher than VV-polarization backscattering coefficients after effective tillering stage(mid-June) Relationships between backscattering coefficients and the rice growth parameters Biomass, LAI was correlated with HH-backscattering coefficients in L-band X-band was sensitive to grain maturity at near harvesting season Prediction of rice growth parameters using backscattering coefficients in L, C, X-band 21

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