Statistical analysis of flow characteristics in the coastal zone

This paper presents analyses of flow characteristics in the near-shore and offshore environment using data from the Danish wind monitoring network. In this relatively high wind speed environment the temporal auto-correlation of wind speeds measured in the offshore coastal zone at or above a height of 40m is not significantly higher than that from land masts.

However, the persistence of wind speeds above typical wind turbine cut-in speeds is higher at coastal and offshore masts. The parameters of wind speed distributions calculated for the onshore and offshore data indicate that both the mean and form of the distribution is modified during offshore flow.

It is shown that in the near-surface layer vertical propagation of the modified momentum flux differentially affects the body and tails of the wind speed distribution. These analyses further indicate that at a height of 50m under stable stratification the flow has not fully adjusted to the differing fluxes over the sea even after an over water fetch of at least 11–20km.