Abstract
Wind speeds for a nominal height of 10 m and from the lowest model level (∼70 m above ground level) from the Rossby Center
regional climate model (RCM) (RCA3) run at four resolutions between approximately 50 × 50 km and 6 × 6 km are analyzed to
assess the effect of model resolution on wind climates. The influence of model resolution in this topographically simple subdomain
of northern Europe is more profound in the wind extremes than in the central tendency. The domain-averaged mean wind speed
at 10 m increases by 5\% as the resolution increases from 50 to 6.25 km, while the 50 year return period wind speed and wind
gust at this height increase by over 10\% and 24\%, respectively. Larger changes are observed in these wind speed metrics at
the lowest model level as model resolution increases (∼+10\% in the mean and ∼+20\% in the 50 year return period wind speed).
These differences are of similar magnitude to the climate change signal in extreme wind events derived in prior research and
may have implications for climate change risk and vulnerability analyses. Output from the lowest model level indicates some
evidence for increased variability at synoptic and meso-α time scales with increased model resolution, but the effect is nonlinear. Furthermore, analysis of power spectra of grid
cell average and tile fraction wind speeds at 10 m does not support the assertion that increased model resolution increases
model skill at synoptic and meso-α time scales relative to in situ observations.
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