1. Dialogue, equality and trust are keywords in our relations with our employees and all our collaboration partners www.risoe.dk Wind resources and wind farm wake effects offshore observed from satellite Charlotte Bay Hasager Poul Astrup Merete Bruun Christiansen Morten Nielsen Rebecca Barthelmie Risø National Laboratory, Wind Energy Department

2. EWEC 2006, Athens 27 February to 2 March 2006 Motivation Satellite data are complementary to: offshore in-situ data……….that are costly offshore model results…….that are not fully verified

3. EWEC 2006, Athens 27 February to 2 March 2006 1800 km 400 km 100 km

4. EWEC 2006, Athens 27 February to 2 March 2006 Physics Ocean surface is roughened by wind interaction such that capillary and short gravity waves are generated. More wind causes more steep waves that causes higher backscatter.

5. EWEC 2006, Athens 27 February to 2 March 2006 Courtesy: NOAA Horns Rev, Elsam A/S

6. EWEC 2006, Athens 27 February to 2 March 2006

7. QuikScat Mean wind speed 5 years Number of observations: 3650 (twice per day for 5 years) Grid cell: ca. 25 km

8. EWEC 2006, Athens 27 February to 2 March 2006 QuikScat North

9. EWEC 2006, Athens 27 February to 2 March 2006 QuikScatEast

10. EWEC 2006, Athens 27 February to 2 March 2006 QuikScatSouth

11. EWEC 2006, Athens 27 February to 2 March 2006 QuikScat West Weibull A and k per sector in WASP tab-file format available

12. EWEC 2006, Athens 27 February to 2 March 2006 Wind field from Envisat ASAR WSM (Courtesy: JHU/APL) Horns Rev, Elsam A/S

13. EWEC 2006, Athens 27 February to 2 March 2006

15. Envisat processed at JHU/APL

16. EWEC 2006, Athens 27 February to 2 March 2006

17. From Nielsen et al. 2004, Risø-R-1479(EN) Horns Rev (Denmark) 5 km ERS Mean wind speed for 30 days Grid cell: 400 m

18. EWEC 2006, Athens 27 February to 2 March 2006 91 SAR wind maps Directions from image, LG supervised U = 7.8 m/s E = 496 W/m 2 Directions from met. mast U = 7.3 m/s E = 421 W/m 2 Directions from image, LG automatic U = 7.7 m/s E = 510 W/m 2 In situ measurements (Sommer, 2003): U = 7.6 m/s E = 422 W/m 2

19. EWEC 2006, Athens 27 February to 2 March 2006

20. Wind farm sites ERS (no wind) Horns Rev Offshore Wind Farm Blaavandshuk Met. mast N

21. EWEC 2006, Athens 27 February to 2 March 2006 Wind farm ERS Horns Rev Wind farm wake effects Reduced mean wind speed Enhanced turbulence

22. EWEC 2006, Athens 27 February to 2 March 2006 x y YXYX

23. Airborne SAR (E-SAR) 12 October 2003 Wind Met. mast 5 flight tracks in C-band VV

24. EWEC 2006, Athens 27 February to 2 March 2006 Winds from E-SAR in CVV Wind farm Wind Wind speedVelocity deficit

25. EWEC 2006, Athens 27 February to 2 March 2006 Christiansen & Hasager (2006), Using airborne SAR for wake mapping offshore. Wind Energy (in press).

26. EWEC 2006, Athens 27 February to 2 March 2006 Acknowledgements: Danish Research Agency SAT-WIND and SAR-WAKE projects; ESA EO-windfarm and EO-1356 projects; Elsam A/S Meteorological data. Wind resources can be estimated from satellite wind maps as a supplement to in-situ data. Wake velocity deficit can be quantified from satellite wind maps. Conclusions