DOWA

The Dutch Offshore Wind Atlas (DOWA) provides a 10 year wind climatology for the North Sea.

The Dutch Offshore Wind Atlas was made by KNMI as part of the DOWA-project. The DOWA-project is executed by project partners “ECN part of TNO”, Whiffle and KNMI and supported with Topsector Energy subsidy from  the Ministry of Economic Affairs and Climate Policy  (SDE+ Hernieuwbare Energie Call).

There is another wind atlas made by KNMI: the KNMI North Sea Wind (KNW) Atlas. If you are interested in long-term statistical values such as averages and extremes, the KNW-atlas is hard to beat. But the hourly correlation with measurements (e.g. daily cycle) in the KNW-atlas is rather poor. And the KNW-atlas lacks information above 200 meter height and information that enables further downscaling with Large Eddy Simulation (LES) methods. That is why KNMI made the Dutch Offshore Wind Atlas (DOWA). The DOWA is a 10 year climatology (2008-2017) with a better hourly correlation than the KNW-atlas, information up to 600 m heights and the option to downscale the information in DOWA from hourly to less than 60 seconds and from 2.5 km to less than 100 m horizontally. Also the domain is larger than that of the KNW-atlas, including the areas where the German wind farms are (being) built and planned. The DOWA-data and all information on the DOWA-project will become available on the 17th of January 2019 via the DOWA-project website: www.dutchoffshorewindatlas.nl.

In the table below the main differences between KNW and DOWA are summarized.

The DOWA is validated against satellite measurements and (ASCAT) and offshore meteorological mast and LiDAR measurements by “ECN part of TNO” in close cooperation with KNMI. There is a significant improvement of correlation with measurements (e.g. daily cycle) in the DOWA (validation reports on www.dutchoffshorewindatlas.nl)

Making the DOWA (and updating the KNW-atlas with more recent years) is only part of the DOWA-project. The main innovations in the project are:

  1. The new models and methodology to make the  DOWA
  2. The way to nest Large Eddy Simulations in mesoscale weather model HARMONIE
  3. The way to include wind farm (cluster) wake effects in mesoscale weather model HARMONIE
  4. Low level jets and their impact on wind turbine performance
  5. Wind turbine parametrization in GRASP (Whiffles GPU-based Large Eddie Simulations)
  6. Scanning LiDAR measurements to assess high altitude wind

 

DOWA and KNW domains and orography
DOWA and KNW domains and orography
Main differences between KNW and DOWA
Main differences between KNW and DOWA
Wind speed, 100 m, 2008-2017 mean
Wind speed, 100 m, 2008-2017 mean