1. SVW Requirements Workshop Miami, FL 5-7 June, 2006 Airborne Measurements of Ocean Backscatter Daniel Esteban Fernandez Acknowledgements: NOAA NESDIS Office Research & Applications NOAA Aircraft Operations Center University of Massachusetts

2. SVW Requirements Workshop 5-7 June, 2006, Miami Outline IWRAP – Description and measurement technique Scatterometry Geophysical Model Functions (GMFs) – Methodology – Dual-band (C and Ku), dual-polarized (H and V) GMFs from IWRAP measurements

3. SVW Requirements Workshop 5-7 June, 2006, Miami IWRAP Measurement Technique Reflectivity and Doppler profiles – four beams, two frequencies (C and Ku), two polarizations (H and V) – simultaneously. High-resolution surface and volume backscatter

4. SVW Requirements Workshop 5-7 June, 2006, Miami IWRAP Designed to Investigate… Hurricane Katrina, August 28 th, 2005

5. SVW Requirements Workshop 5-7 June, 2006, Miami Summary of datasets Flown during 2002, 2003, 2004 and 2005 Hurricane seasons, and the 2003 and 2005 Winter Storm experiments: 70 missions, including flights through hurricanes Gustav, Isidore, and Lili (2002), Fabian and Isabel (2003), Frances and Ivan (2004), Ophelia and Rita (2005), as well as several TDs, TSs and extra-tropical storms. Collected measurements of ocean surface winds up to 72 m/s and rain rates over 100 mm/hr, and boundary layer winds in excess of 100 m/s. Several flights coincident with WindSAT and QuikSCAT passes. Hundreds of GPS drop-sondes deployed. Collocated radiometer (SFMR) brightness temperatures measurements providing surface wind speed and precipitation estimates.

6. SVW Requirements Workshop 5-7 June, 2006, Miami Work performed Obtained dual-polarized (H and V) C- and Ku-band model functions of ocean backscatter versus wind speed and direction: – Wind speed > 25 m/s in rain-free conditions. – C-band H polarization (full range). Compared against other models (CMOD4/5, NSCAT2, QSCAT1, etc.): – Shown a decreased sensitivity at high-winds. – Developed the model for the QuikSCAT incidence angles. – Implemented in a parallel NOAA/NESDIS/ORA NRT QuikSCAT 25-km and 12.5-km processor.

7. SVW Requirements Workshop 5-7 June, 2006, Miami High Winds Ku-band Model Function log 25

8. SVW Requirements Workshop 5-7 June, 2006, Miami High Winds C-band Model Function log

9. SVW Requirements Workshop 5-7 June, 2006, Miami Full-range C-band H pol. models

10. SVW Requirements Workshop 5-7 June, 2006, Miami A2/A0 versus wind speed C-band VV C-band HH Ku-band VV Ku-band HH

11. SVW Requirements Workshop 5-7 June, 2006, Miami C-band NRCS Azimuthal response VV 50 deg HH 49 deg

12. SVW Requirements Workshop 5-7 June, 2006, Miami Ku-band NRCS Azimuthal Response VV 48 deg HH 48 deg

13. SVW Requirements Workshop 5-7 June, 2006, Miami Conclusions C- and Ku-band mean ocean backscatter measurements show a decreased sensitivity for wind speeds above ~45 m/s. H-pol behaves similarly to V-pol for both C- and Ku-band at high wind speeds, but… C-band H-pol at high incidence angles shows a much higher saturation point (not reached at 65 m/s). C- and Ku-band A 2 /A 0 measurements decrease to < 0.1 thus supporting the observed decreased sensitivity in wind direction as well. Best bet to retrieve high winds (> 50 m/s) from scatterometry is C-band H-pol at high incidence angles.