hasager, c.b., badger, m., peña, a., hahmann, a., volker, p. · pdf filehasager, c.b.,...
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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.
DTU Wind Energy, Technical University of Denmark
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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
DTU Wind Energy, Technical University of Denmark
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SAR wind data archive at DTU
4
• 15,000+ ENVISAT ASAR scenes (2002-2011)
• 26,000+ Sentinel-1A SAR scenes (2014->)
DTU Wind Energy, Technical University of Denmark
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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)
DTU Wind Energy, Technical University of Denmark
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Sentinel-1a wind map
Wind field from Sentinel-1A, 25 April 2015 at 05:40 UTC
DTU Wind Energy, Technical University of Denmark
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Wind resource mapping
DTU Wind Energy, Technical University of Denmark
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NORSEWInD 10-m wind atlas from Envisat ASAR
5/23/2016 8
DTU Wind Energy, Technical University of Denmark
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9 5/23/2016
DTU Wind Energy, Technical University of Denmark
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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.
DTU Wind Energy, Technical University of Denmark
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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)
DTU Wind Energy, Technical University of Denmark
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Wind speed comparisons
Sentinel-1A SAR vs. GFS model Envisat ASAR vs. GFS model
DTU Wind Energy, Technical University of Denmark
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Preliminary 10-m atlas for Europe
Envisat ASAR and Sentinel-1A combined
DTU Wind Energy, Technical University of Denmark
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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
DTU Wind Energy, Technical University of Denmark
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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)
DTU Wind Energy, Technical University of Denmark
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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.
DTU Wind Energy, Technical University of Denmark
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Stability correction at 100 m
The South Baltic Sea
DTU Wind Energy, Technical University of Denmark
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Long-term average wind profile
Fino-2 in the South Baltic Sea
𝜅 𝑢(𝑧)
𝑢∗= ln
𝑧
𝑧0− 𝜓𝑚
DTU Wind Energy, Technical University of Denmark
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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.
DTU Wind Energy, Technical University of Denmark
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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.
DTU Wind Energy, Technical University of Denmark
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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
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