IGARSS 2010 Honolulu Hawaii July 25 30 2010

IGARSS 2010, Honolulu Hawaii, July 25 -30, 2010 Estimationg rice growth parameters using X-band scatterometer data Yihyun Kim 1*, S. Young Hong 1, Eunyoung Choe 1 and Hoonyol Lee 2 1 National Academy of Agricultural Science, RDA, Korea 2 Department of Geophysics, Kangwon National University, Korea

Contents 1 Background 2 Material and Methods 3 Results 4 Conclusion

Background q Rice is one of the major crops in Korea q Microwave radar can penetrate cloud cover regardless of weather condition q Ground-based polarimetric scatterometer has advantage of monitoring crop conditions with full polarization and various frequencies q Plant parameters such as LAI, biomass, plant height are highly correlated with backscattering coefficients q 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 q 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) q 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 l To analyze scattering characteristics of paddy rice obtained from L, C, X-band automatic scatterometer system l Relationship between backscattering coefficients in L, C, X-band plant parameters with full polarization l Prediction of rice growth parameters using backscattering coefficients in L, C, X-band

q Study site - An experimental field at NAAS, Suwon, Korea Ø Testing varieties : Chuchoungbyeo Ø The size field : 660 m 2

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

Materials and Methods q Specification of the L, C, X-band automatic scatterometer system Specification L-Band C-Band X-Band Center frequency 1. 27 GHz 5. 3 GHz 9. 65 GHz Bandwidth 0. 12 GHz 0. 6 GHz 1 GHz 201 801 1601 Antenna type Dual polarimetric horn Antenna gain 12. 4 d. B 20. 1 d. B 22. 4 d. B Range resolution 1. 25 m 0. 15 m Wavelength 0. 23 m 0. 056 m 0. 031 m Polarization HH, VV, HV, VH 4. 16 m Number of frequency points Platform height

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

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

Results 110 5. 0 100 4. 5 90 4. 0 80 3. 5 70 heading stage 3. 0 60 LAI planh height(cm) q Temporal variations in growth parameters during rice growth 50 2. 5 2. 0 40 1. 5 30 20 1. 0 10 0. 5 0. 0 0 0 10 20 30 40 50 60 70 80 90 100110120130140150 DAT(Day After Transplanting) <Plant height> 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 DAT(Day After Transplanting) <Leaf Area Index>

Results q Temporal variations in growth parameters during rice growth heading stage 200 400 180 350 300 Dry biomass(g/m 2) Fresh biomass(g/m 2) 160 250 200 150 100 140 120 100 80 60 40 50 20 0 10 20 30 40 50 60 70 80 90 100110120130140150 DAT(Day After Transplanting) <Fresh biomass> 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 DAT(Day After Transplanting) <Dry biomass>

Results q Temporal variations of backscattering coefficients at polarization and incident angle 45° for the L-band 0 -5 scatt. coeff. (d. B) -10 -15 -20 -25 -30 -35 -40 VV VH HV HH -45 -50 -55 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 DOY(Day of year) booting stage ~ heading stage (most active rice growth period)

Results q Temporal variations of backscattering coefficients at polarization and incident angle 45° for the C-band 0 -5 scatt. coeff. (d. B) -10 -15 -20 -25 -30 -35 -40 VV -45 VH -50 HV HH -55 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 DOY(Day of year)

Results q Temporal variations of backscattering coefficients at polarization and incident angle 45° for the X-band 0 -5 scatt. coeff. (d. B) -10 -15 -20 -25 -30 -35 -40 VV VH HV HH -45 -50 -55 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 DOY(Day of year)

Results q Relationship between backscattering coefficients at L, C, X-band plant variables v L-band VV HH HV Incident angle Plant Height LAI Tfw (g/m 2) Gdw (g/m 2) Plant height LAI Tfw (g/m 2) Gdw (g/m 2) 45 0. 80** 0. 91*** 0. 90*** -0. 78** 0. 89*** 0. 98*** 0. 96*** -0. 74** 0. 79** 0. 93*** 0. 89*** -0. 62* v C-band VV HH HV Incident angle Plant height LAI Tfw (g/m 2) Gdw (g/m 2) 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** v X-band VV HH HV Incident angle Plant height LAI Tfw (g/m 2) Gdw (g/m 2) 45 0. 63* 0. 66* 0. 73** 0. 94*** 0. 72** 0. 81** 0. 84** 0. 79** 0. 68* 0. 83** 0. 70*

Results q Optimum condition for estimation of rice growth parameters Optimum condition Band Polarization R 2 Plant height(cm) L-band HH R 2=0. 86*** Leaf Area Index L-band HH R 2=0. 96*** Above ground L-band HH R 2=0. 94*** Grain X-band VV R 2=0. 91*** X-band VV R 2=0. 94*** Growth parameters Fresh Biomass(g/m 2) Grain dry weight(g/m 2)

Results q Prediction of Leaf Area Index using backscattering coefficients(L-band, HH) 5. 0 4. 5 4. 0 = 0. 9624 Predicted LAI by modeling('09) R 2 3. 5 LAI 3. 0 2. 5 2. 0 1. 5 1. 0 0. 5 4. 5 y = 0. 8739 x + 0. 4459 4. 0 R 2 = 0. 95*** RMSE = 0. 2346 3. 5 3. 0 2. 5 2. 0 1. 5 1. 0 0. 5 0. 0 -35 -30 -25 -20 -15 -10 -5 Backscattering coefficients(L-band, HH, d. B) 0 0. 5 1. 0 1. 5 2. 0 2. 5 3. 0 Measured LAI('08) 3. 5 4. 0 4. 5 5. 0

Results q Prediction of Biomass using backscattering coefficients (L-band, HH) 400 Total fresh weight(g/m 2) 350 Estimated total fresh weight by modeling(09) 450 R 2 = 0. 9129 300 250 200 150 100 50 0 -40 -35 -30 -25 -20 -15 -10 -5 Backscattering coefficients(L-band, HH, d. B) 0 y = 1. 0028 x – 0. 5471 400 R 2 = 0. 95*** 350 RMSE = 8. 5412 300 250 200 150 100 50 0 0 50 100 150 200 250 300 Measured total fresh weight(08) 350 400

Results q Prediction of Grain dry weight using backscattering coefficients (X-band, VV) Grain dry weight(g/m 2) 40 Predicted grain dry weight by modeling('09, g/m 2) 45 R 2 = 0. 9345 35 30 25 20 15 10 -20 -19 -18 -17 -16 -15 -14 -13 Backscattering coefficients (X-band, VV, d. B) -12 40 y = 1. 1099 x – 1. 3067 35 R 2 = 0. 96*** RMSE = 1. 7685 30 25 20 15 10 10 15 20 25 30 35 Measured grain dry weight ('08, g/m 2) 40

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