Estimation of rice growth parameters by X-band radar backscattering data

1. ISRS2008, KIGAM, Daejeon, Korea, Oct 29-31, 2008 Estimation of rice growth parameters by X-band radar backscattering data Yi-hyun Kim1*, S.Young Hong1 and Hoonyol Lee2 1National Academy of Agricultural Science, RDA, Korea 2 Department of Geophysics, Kangwon National University, Korea

2. Contents 1 Background 2 Material and Methods 3 Results 4 Conclusion

3. 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)

4. 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) • Polarimetric SAR(POLSAR) has the potential to estimate volume, surface and • double bounced scattering through the data decomposition methods • Backscattering coefficients from a ground scatterometer are often affected by • weather condition the necessity of near-continuous automatic measurement • has arisen by the experiment of previous year(Kim et al, 2007)

5. Objective • To analyze scattering characteristics of paddy rice obtained from • automatic scatterometer system • Relationship between backscattering coefficients in X-band and • plant parameters with full polarization

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

7. Materials and Methods • X-band automatic scatterometer system

8. Materials and Methods • Specification of the automatic scatterometer system

9. Radar backscattering measurement • - Between before transplanting(15, May) and harvesting stage(12, Oct) • Growth data collection Transplant stage (mid-May) Panicle formation stage (mid-July) Harvesting stage (mid-Oct) Heading stage (mid-Aug)

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

11. Polarimetric decomposition (Pauli decomposition) - Pauli basis (2x2 matrices), (Pottier et al., 2005) : Scattering matrix α: single bounce scattering β: double bounce scattering γ: volume scattering

12. Results • Temporal variations of backscattering coefficients at polarization and • incident angle 45° for the X-band 2008 2007

13. Results • Polarimetric decomposition of X-band radar backscattering data • - Pauli decomposition

14. Results • Relationship between backscattering coefficients at X-band and plant variables < 2008 > < 2007 >

15. Results • Correlation between X-band backscattering coefficients and grain dry • weight < 2008 > < 2007 >

16. Results • Relationship between vv-backscattering coefficients in X-band and grain • dry weight

17. Results • Relationship between measured and estimated grain dry weight after • heading stage y=0.8183x+3.3132 R2=0.82** RMSE=1.0154

18. Conclusions • Backscattering coefficients of rice crop were investigated with an autoamtically • -operating ground-based scatterometer • The temporal variations of the backscattering coefficients of the rice crop at • X-band during rice growth period • HH-polarized backscattering coefficients higher than vv-polarized backscattering • coefficients after panicle initiation stage • Polarimetric decomposition of paddy data such as single, double and volume • scattering to extract the scattering information • Relationships between backscattering coefficients and the plant parameters • Grain weight was correlated with vv-backscattering coefficient in X-band • X-band was sensitive to grain maturity at near harvesting season

19. Thank You !