3. Scatterometer ( Bragg roughness ) Composite surface Bragg theory Altimeter ( LP-Filtered roughness ) According to the 2 θ deviation, the phase shift causes constructive (left figure) or destructive (right figure) interferences (Wikipedia)

4. Hwang 2011 Hwang 2008 Plant 2002 Elfouhaily 1997 CB theory matured by 1960s, but …

5. Hwang 2011 Hwang 2008 Plant 2002 Elfouhaily 1997 CB theory matured by 1960s, but …

6. Decreasing sensitivity with wind Saturation/dampening Increasing sensitivity with wind: Linear: low wind Cubic: high wind Hwang et al. 2010 R2 and CB in good agreement R2 >> CB Breaking contribution missing in CB computation RADARSAT-2 quad-polarimetric data VV HH HV

7. Hwang et al. 2010 VV,HH: CMOD5 rms 1.50 rms 1.62 rms 1.67 rms 1.65

8. Hwang et al. 2010

9. Quad-pol (25 km x 25 km) Dual-pol (300 km x 300 km or 500 km x 500 km) Black: Quad-pol (# 427); Blue: Dual-pol (# 372)

10. Quad-pol (25 km x 25 km) Dual-pol (300 km x 300 km or 500 km x 500 km) Noise subtracted

12. Linear U10(VH) B: 0.000, c': 0.971, D: 1.989, R: 0.819, SI: 0.261 VH noise sub. B: -0.022, c': 0.965, D: 1.901, R: 0.837, SI: 0.250 VH w/ noise B: -0.020, c': 0.965, D: 1.912, R: 0.835, SI: 0.251

13. -31 dB noise subtracted

14. Vachon and Wolfe 2011

15. Donnelly et al. 1999 Airborne high wind data Radar: Co-pol saturation problem 22  32.5  43.5  54  Wind speed U 10 5 20 45 m/s Normalized Radar Cross Section (dB)

16. Radiometer: if saturation, it’s at a much higher wind speed because the foam factor. Hwang (2011, TGRS, submitted) Data: Meissner and Wentz (2009) WindSat global analysis

17. Radiometer: If saturation, it’s at a much higher wind speed. Hwang (2011, TGRS, submitted)

18. Radiometer: If saturation, it’s at a much higher wind speed. Hwang (2011, TGRS, submitted) V: black; H: red

19. RADARSAT-2 polarimetric data Quad-pol (25 km x 25 km) Dual-pol (300 km x 300 km or 500 km x 500 km) VH VH -noise VV HH VH