An analysis of surface meteorological data, recorded by the West-European synoptic network in June and July 1976, reveals the existence of a diurnal oscillation of surface geostrophic wind in this part of Europe. The oscillation is similar to that observed in the Great Plains of the United States by several investigators.

The analysis delineates physical factors involved in this diurnal oscillation of geostrophic wind. As found by others, the oscillation is induced partly by the diurnal temperature cycle over sloping terrain. Our analysis suggests that a diurnal variation of the horizontal gradient of the temperature field in the atmospheric boundary layer is another major factor contributing to the observed oscillation of geostrophic wind.