Simulated wind power off‐shore using different parametrizations for the sea surface roughness

Abstract

The equation for the dependence of the Charnock constant on wave age proposed by o}!shore^ Johnson et al. (Journal of Physical Oceanography 1998; 28: 1702Ð1716) is extended to resource include conditions of very young waves or short fetches. The effect on the simulated assessment^ average wind speed and average wind power density off a straight east coast in Denmark wind power meteorology^ is investigated by numerical simulations. Calculations are also performed employing the strati_cation^ classical Charnock relation and a constant roughness of the sea. The formulations with roughness variable sea surface roughness are combined with the equation for a smooth water surface for low winds. The wind climate is calculated with the Karlsruhe Atmospheric Mesoscale Model (KAMM) in 84 classes of the geostrophic wind. The difference between the fetch-dependent and the fetch-independent formulation is very small. Even a constant sea surface roughness yields good results near the coast. The influence of stratification, i.e. temperature differences between sea and land, is much more important than the fetch dependence of the sea surface roughness.