ANALYSIS OF THE EFFECT OF THE COASTAL DISCONTINUITY ON NEAR-SURFACE FLOW

Conditional sampling is used herein to examine the effect of fetch, st ability, and surface roughness changes on wind speeds in the coastal z one. Using data from an offshore wind farm it is shown that at a dista nce of 1.2-1.7 km from the coast, up to a height of 20 m above the sur face, differences in wind speed distributions from onshore and offshor e masts are statistically significant for flow moving offshore under a ll stability conditions. In contrast, differences between the distribu tion of wind speeds at 38 and 48 m at masts located at the coast and i n the coastal zone are not significant for flow moving offshore: indic ating that flow at these heights is not fully adjusted to the change i n surface roughness (land to sea). These findings are in accordance wi th calculations of the internal boundary layer (IBL) height which indi cate that the IBL would frequently be below the two upper measurement heights at 1.2-1.6 km from the coast. The analyses presented here indi cate that the wind speed distribution at a potential offshore wind far m site is not solely dependent on fetch (distance from the coast) but also depends on the stability climate.