A Climatological Study of Boundary Layer Wind Speed Using a Meso-γ-Scale Higher-Order Closure Model

Abstract

A mesoscale higher-order closure atmospheric boundary layer model has been used to get more detailed information than is possible from observations regarding horizontal and vertical variations of the wind in an area in southeastern Sweden. To keep the computer time realistic, the number of model runs has to be kept at a minimum. The factors primarily affecting the wind field were thus identified. To get accurate results it was necessary to make simulations representing the four seasons, eight wind directions, three values of the geostrophic wind speed, and three mean temperatures over land, while the sea surface temperature was kept at its monthly average. The model was run for these 288 conditions with the monthly mean of the daily temperature cycle at screen height over land in order to include the effects of variations in thermal stratification. The simulated wind fields were weighted together using climatological data on the geostrophic wind and the screen height temperature, determined from weather stations in the area. A comparison between modeled climatological mean wind and observations at three weather stations show good agreement with both monthly and annual data.