Influence of terrain roughness on numerical simulations of sea-breezes

Land- and sea-breezes are attracting increasing interest for wind energy applications. While these thermally-driven winds are weaker than synoptic winds, their high regularity makes them appealing for the renewable energy sector. In this study, we simulate breezes using a simple model based solely on temperature and terrain roughness data. The simulation focuses on the Llobregat river delta, in the northeast of the Iberian Peninsula, using temperature measurements from a meteorological mast at four different heights. The mast is also equipped with two anemometers. Daily wind profiles were collected during more than a year, and a day characterized by thermal winds was selected for detailed analysis. Numerical simulations of breezes were conducted using the open-source computational fluid dynamics code OpenFOAM v2312. The influence of roughness on the simulation results was examined. Vertical temperature profiles and velocity magnitudes of breezes were obtained and compared with observations. Results demonstrate that the input of terrain roughness and temperature allow a reliable qualitative study of sea-breezes. They also indicate a significant sensitivity of the thermal boundary layer to roughness height. Although the impact of roughness on wind speed intensity is lower, increase in roughness leads to a reduction in wind speed and earlier sea-breeze onset. • Numerical simulations show moderate night land-breezes and stronger day sea-breezes. • Simulated temperature profile highly sensitive to the choice of roughness height. • Moderate roughness rise reduces wind speed and causes earlier sea-breeze onset. • Simulated breeze intensity is weaker than observational data.