Hasager, C.B., Badger, M., Peña, A., Hahmann, A., Volker, P. · PDF fileHasager, C.B., Badger, M., Peña, A., Hahmann, A., Volker, P. DTU Wind Energy, Technical University of...

Lifting satellite winds from 10 m to hub-height

23 May 2016 VindkraftNet meeting, DONG Energy, Skærbæk

Hasager, C.B., Badger, M., Peña, A., Hahmann, A., Volker, P.

DTU Wind Energy, Technical University of Denmark

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Motivation

We have: Satellite wind maps valid at 10 m height at 1 km by 1 km spatial resolution. It is the equivalent neutral wind, i.e. not real wind. WRF can provide results on stability. We would like to have: Estimate of wind resource at 100 m, i.e. with stability-dependent winds combining satellite winds and WRF stability.



Envisat ASAR and Sentinel-1a/b

Artist's view of the deployed Sentinel-1 spacecraft (image credit: ESA, TAS-I) Sentinel-1A - 03 April 2014. Sentinel-1B - 25 April 2016. Operational lifespan: 7 years (with consumables for 12).

Envisat 2002-2012 10 years data archive Envisat concept art via ESA



SAR wind data archive at DTU

4

• 15,000+ ENVISAT ASAR scenes (2002-2011)

• 26,000+ Sentinel-1A SAR scenes (2014->)



SAR Operational Products System (SAROPS)

• SAR wind retrieval in near-real-time (< 6h from data acquisition) at DTU for the European Seas since 2005.

SAR

GFS

Ice

Wind maps

Download and pre-processing

SAROPS

Wind

resource maps

(10 m)

S-WAsP WRF + MOST

Wind

resource maps

(100 m)

Wind retrieval (APL/NOAA)

Wind resource assessment (DTU)

Wind resource extrapolation (DTU)



Sentinel-1a wind map

Wind field from Sentinel-1A, 25 April 2015 at 05:40 UTC



Wind resource mapping



NORSEWInD 10-m wind atlas from Envisat ASAR

5/23/2016 8



9 5/23/2016



SAR and mast wind comparisons

5/23/2016 10

0.00

0.50

1.00

1.50

2.00

Horns Rev M2

Egmond aan Zee

Fino-1 Horns Rev M7

Greater Gabbard

RMSE

R2

Wind speeds from SAR and 5 masts in the North Sea,

At Horns Rev M2 and Egmond aan Zee we have information to derive the atmospheric stability.

Hasager, C.B. et al. (2015): Offshore wind climatology based on synergetic use of Envisat ASAR, ASCAT and QuikSCAT. Remote Sensing of Environment, 156, 247–263. 10.1016/j.rse.2014.09.030.



The New European Wind Atlas (NEWA)

•Larger area

•Envisat ASAR and Sentinel-1 A/B

•Extrapolation to different heights up to 100 m

•Extensive measurement campaigns and modeling

Coverage of the satellite based atlas in NEWA

(image courtesy Google Earth)



Wind speed comparisons

Sentinel-1A SAR vs. GFS model Envisat ASAR vs. GFS model



Preliminary 10-m atlas for Europe

Envisat ASAR and Sentinel-1A combined



Wind speed extrapolation to 100 m

5/23/2016

Peña, A. & Hahmann, A.N. (2012): Atmospheric stability and turbulence fluxes at Horns Rev – an intercomparison of sonic,

bulk and WRF model data, Wind Energy, 15, 717-731, DOI: 10.1002/we.500.

Horns Rev M2 mast The North Sea



Frequency distribution of 1/L

• Obukhov length, L

- from WRF outputs of UST, T2 and HFX:

15

𝐿𝑊𝑅𝐹 = −𝑈𝑆𝑇3 𝑇2

𝑔 𝜅 𝐻𝐹𝑋

L > 0: stable

L ≤ 0: unstable

Distribution of 1/L from WRF outputs at Fino-2 (2006-11)



Long-term stability correction

• Probability density function of 1/L:

• Long-term standard deviation:

𝜎± = 𝑔

𝑇2

𝐻𝐹𝑋− 𝐻𝐹𝑋± 2

𝑈𝑆𝑇3

• Long-term stability correction:

𝑃 = 𝑛±

𝐶±

𝜎± exp −(𝐶± 1/𝐿 / 𝜎±)2/3

Γ 1 + 3/2

𝜓𝑚 = −𝑛+

3𝜎+

𝐶+ 𝑏′𝑧 + 𝑛− 𝑓−

Kelly, M. and Gryning, S.-E. (2010): Long-term mean wind profiles based on similarity theory, Boundary-Layer Meteorology, 136, 377-390.



Stability correction at 100 m

The South Baltic Sea



Long-term average wind profile

Fino-2 in the South Baltic Sea

𝜅 𝑢(𝑧)

𝑢∗= ln

𝑧

𝑧0− 𝜓𝑚



Wind speed extrapolated to 100 m

Without stability correction With stability correction

Badger, M. et al.: Extrapolating satellite winds to turbine operating heights, Journal of Applied Meteorology and Climatology, 44, 975-991, doi: 10.1175/JAMC-D-15-0197.1.



Conclusions

• The bias on SAR wind speeds with respect to GFS model wind speeds is lower for Sentinel-1A than for Envisat ASAR.

• Extrapolation of SAR winds to the turbine height can be achieved through application of a modelled long-term stability correction to the wind profile.



Acknowledgements

Satellite data:

The European Space Agency (ESA)

SAR wind retrieval systems:

JHU/APL and NOAA

Collecte Localisation Satellites (CLS)

Mast observations:

All mast data accessed through the NORSEWInD project. Horns Rev: DONG energy and

Vattenfall, Fino-1 and Fino-2: Deutsches Windenergie Institut, Egmond an Zee:

NoordZeewind, Greater Gabbard: SSE Renewables.

Funding:

EU-NORSEWInD, South Baltic OFFER, New European Wind Atlas

Collaboration:

Frank Monaldo & Christopher Jackson, NOAA; Alexis Mouche, IFREMER




Journal of Applied Meteorology and Climatology, 44, 975-991, doi: 10.1175/JAMC-D-15-0197.1.

Hasager, C.B., Badger, M., Peña, A., Hahmann, A., Volker, P. · PDF fileHasager, C.B., Badger, M., Peña, A., Hahmann, A., Volker, P. DTU Wind Energy, Technical University of...

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