offshore wind resource mapping in the european seas in the ... · 23 october 2019 dtu wind energy...

DTU Wind Energy23 October 2019

Charlotte Hasager1, Andrea N. Hahmann1, Tobias Ahsbahs1, Ioanna Karagali1, Tija Sile2, Merete Badger1, Jakob Mann1

1DTU Wind Energy, 2University of Latvia

Offshore wind resource mapping in the European Seas in

the New European Wind Atlas

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WRF New European Wind Atlas

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Note: All results are from Hasager et al. Wind Energ. Sci. Discuss. (in review)

Mean wind speed from mesoscale model at 100 m height for 1989 to 2018 with 3 km resolution


Questions• WRF vs. ERA5 offshore wind speed. Do you expect to find difference, and if yes what

differences?

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• WRF vs. satellite winds offshore. Do you expect to find difference, and if yes what differences?


ERA5 minus WRF wind speed (m/s) at 100m

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Note: WRF has 30-minute values from 30-years (525,912 samples) with 3 km resolution. ERA5 has hourly values from 30-years interpolated to same grid as WRF (262,956 samples) with 27 km resolution.


We learned• ERA5 mean wind speeds at 100 m tend to be lower near coastlines than WRF• ERA5 mean wind speeds at 100 m tend to be higher far offshore than WRF

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ASCAT satellite vs. WRF mean wind speed at 100 m

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Note: ASCAT is 12.5 km resolution


ASCAT - WRF wind speed difference distributionComparing wind speed difference in all grid cells in European Seas

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At 100 m height

Normalized so the areaunder the curve sums to one


Reflections• Any surprises?

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• What may be the reason for lesser discrepancy ASCAT vs. WRF in the North Sea as compared to the Mediterranean Sea?


We learned• WRF agree better with ASCAT in the Northern Seas than in the Mediterranean Sea• Coastal winds are lower in WRF than ASCAT• Bi-modal pdf reflecting the Mediterranean Sea vs. other seas

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Effect of atmospheric stability

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Stability dependent minus neutral meanwind speed difference (m/s) at 100 m

ASCAT at 12.5 km resolutionNote: Satellite winds are extrapolated to 100 m usingstability correction following Badger et al. 2016.


We learned• Unstable conditions are most pronounced near coastlines• More unstable conditions in the Baltic Sea and Black Sea than elsewhere

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Deep dive to Crete• We add Synthetic Aperture Radar satellite wind maps to the analysis

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Envisat Sentinel-1 Sentinel-1 swath Ocean wind speed map2 km resolution


Crete

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Mean wind speed (2002-2018) at 10 m from 549 coinciding model results from ERA5, WRF and satellite.

ERA5 27 km WRF 3 km Satellite SAR 2 km


First assessment• Local wind features absent in ERA5 as compared to WRF and SAR

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Northerly wind

Mean wind speedof 59 cases

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Westerly windsMean wind speedof 57 cases

WRF SARStagnation is flow similar.Lee effect is similar.But gap flow is not

We conclude real orographyis not fully represented by WRF at 3 km.

Similar features resolved in WRF and SAR


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Westerly winds

Mean wind speedof 57 cases

Stagnation flow is similar.Lee effects are similar.Atmospheric waves aresimilar.

We conclude wind features are resolved in WRF


SummaryFirst results on wind statistics in entire European Seas involving WRF, ASCAT and SAR

• WRF compares best to ASCAT in the Northern Seas

• WRF does not resolve all coastal phenomena as observed in SAR

• The results are available for further investigation

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Acknowledgements and further info• This work was supported by the New European Wind Atlas. • We acknowledge Envisat ASAR from ESA, Sentinel-1 SAR from Copernicus, ASCAT

from EUMETSAT and observations from the EU NORSEWIND project.

New European Wind Atlas WRF data are available at:https://map.neweuropeanwindatlas.eu/

Hasager, C. B., Hahmann, A. N., Ahsbahs, T., Karagali, I., Sile, T., Badger, M., and Mann, J.: Europe’s offshore winds assessed from SAR, ASCAT and WRF, Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2019-38 (in review).

Badger, M., Peña. A., Hahmann, A.N., Mouche, A. and Hasager, C.B.: Extrapolating satellite winds to turbine operating heights. Journal of Applied Meteorology and Climatology, doi:10.1175/JAMC-D-15-0197, 2016.

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http://www.neweuropeanwindatlas.eu/

https://doi.org/10.5194/wes-2019-38

offshore wind resource mapping in the european seas in the ... · 23 october 2019 dtu wind energy...

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